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Allow socket code to work after appdomain reload. #13

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Tak
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@Tak Tak commented Oct 20, 2010

Please merge to mono-2-6 as well.

* metadata/socket-io.c: Don't use a static variable to cache the socket assembly image.

License: MIT/X11
@vargaz
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vargaz commented Oct 20, 2010

This might have perf implications, since the caching is now gone. It would be better to add some fields to MonoDomain for example to cache these things.

@Tak
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Tak commented Oct 20, 2010

It's still using mono_image_loaded() for caching.

@vargaz
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vargaz commented Oct 20, 2010

  • mono_image_loaded () is slow
  • mono_class_from_name () is slow
  • there is no caching since socket_assembly is not static

@Tak
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Tak commented Oct 20, 2010

Isn't mono_image_loaded just a hashtable lookup? Is that really too slow?

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vargaz commented Oct 20, 2010

If you need a hash table lookup to create an object, that is slow, those caches were put there for a reason.

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Tak commented Oct 21, 2010

Ok, will rework. Thanks.

lewurm added a commit to lewurm/mono that referenced this pull request Dec 8, 2015
We've seen that error for quite some time:

> `* Assertion at ../../mono/utils/mono-os-mutex.h:71, condition `res != EINVAL' not met`

It looks like there's a race between `finalizer_thread()` and `mono_gc_cleanup()` around
`reference_queue_mutex`. The source of the problem is, `finalizer_thread` could end up
being alive, although `mono_gc_cleanup()` made some effort to kill it and then destroys
`reference_queue_mutex`, while the finalizer thread is still using it in
`reference_queue_proccess_all()`.

> $ MONO_GC_DEBUG=bridge=Bridge MONO_GC_PARAMS=minor=split MONO_ENV_OPTIONS=--gc=sgen MONO_PATH=/home/lewurm/monoperf/mono/mcs/class/lib/net_4_x ../../mono/mini/mono sgen-bridge-major-fragmentation.exe --optimize=all --debug
> [...]
> [12/08/2015 01:49:31] done
> Shutting down finalizer thread timed out.
> * Assertion at gc.c:867, condition `finalizer_thread_exited' not met
>
> Stacktrace:
>
>
> Native stacktrace:
>
>
> Debug info from gdb:
>
> [New LWP 7623]
> [New LWP 7622]
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib/arm-linux-gnueabihf/libthread_db.so.1".
> 0x4043b5f4 in __libc_do_syscall () from /lib/arm-linux-gnueabihf/libpthread.so.0
>   Id   Target Id         Frame
>   3    Thread 0x417ff430 (LWP 7622) "mono" 0x4043b5f4 in __libc_do_syscall () from /lib/arm-linux-gnueabihf/libpthread.so.0
>   2    Thread 0x42573430 (LWP 7623) "Finalizer" 0x0021482a in finalizers_with_predicate (predicate=0x1fd121 <object_in_domain_predicate>, user_data=0x37a348, out_array=0x42572c70, out_size=64, hash_table=0x338f68 <major_finalizable_hash>) at sgen-fin-weak-hash.c:581
> * 1    Thread 0x406c4250 (LWP 7620) "mono" 0x4043b5f4 in __libc_do_syscall () from /lib/arm-linux-gnueabihf/libpthread.so.0
>
> Thread 3 (Thread 0x417ff430 (LWP 7622)):
> #0  0x4043b5f4 in __libc_do_syscall () from /lib/arm-linux-gnueabihf/libpthread.so.0
> #1  0x404371d8 in pthread_cond_wait@@GLIBC_2.4 () from /lib/arm-linux-gnueabihf/libpthread.so.0
> #2  0x00242266 in mono_os_cond_wait (cond=0x346e98 <work_cond>, mutex=0x346e80 <lock>) at ../../mono/utils/mono-os-mutex.h:105
> mono#3  0x00242c1a in thread_func (thread_data=0x0) at sgen-thread-pool.c:118
> mono#4  0x40433fbc in start_thread () from /lib/arm-linux-gnueabihf/libpthread.so.0
> mono#5  0x405a0b3c in ?? () from /lib/arm-linux-gnueabihf/libc.so.6
> Backtrace stopped: previous frame identical to this frame (corrupt stack?)
>
> Thread 2 (Thread 0x42573430 (LWP 7623)):
> #0  0x0021482a in finalizers_with_predicate (predicate=0x1fd121 <object_in_domain_predicate>, user_data=0x37a348, out_array=0x42572c70, out_size=64, hash_table=0x338f68 <major_finalizable_hash>) at sgen-fin-weak-hash.c:581
> #1  0x00214894 in sgen_gather_finalizers_if (predicate=0x1fd121 <object_in_domain_predicate>, user_data=0x37a348, out_array=0x42572c70, out_size=64) at sgen-fin-weak-hash.c:622
> #2  0x001fd16a in mono_gc_finalizers_for_domain (domain=0x37a348, out_array=0x42572c70, out_size=64) at sgen-mono.c:546
> mono#3  0x001ca2a4 in finalize_domain_objects (req=0x47ba68) at gc.c:678
> mono#4  0x001ca3b6 in finalizer_thread (unused=0x0) at gc.c:730
> mono#5  0x001a1392 in start_wrapper_internal (data=0x3b1100) at threads.c:713
> mono#6  0x001a1430 in start_wrapper (data=0x3b1100) at threads.c:760
> mono#7  0x0027097a in inner_start_thread (arg=0xbed58de0) at mono-threads-posix.c:92
> mono#8  0x40433fbc in start_thread () from /lib/arm-linux-gnueabihf/libpthread.so.0
> mono#9  0x405a0b3c in ?? () from /lib/arm-linux-gnueabihf/libc.so.6
> Backtrace stopped: previous frame identical to this frame (corrupt stack?)
>
> Thread 1 (Thread 0x406c4250 (LWP 7620)):
> #0  0x4043b5f4 in __libc_do_syscall () from /lib/arm-linux-gnueabihf/libpthread.so.0
> #1  0x4043a396 in waitpid () from /lib/arm-linux-gnueabihf/libpthread.so.0
> #2  0x000d1b24 in mono_handle_native_sigsegv (signal=6, ctx=0xbed58a80, info=0xbed58a00) at mini-exceptions.c:2235
> mono#3  0x00112424 in sigabrt_signal_handler (_dummy=6, _info=0xbed58a00, context=0xbed58a80) at mini-posix.c:218
> mono#4  <signal handler called>
> mono#5  0x405248e6 in ?? () from /lib/arm-linux-gnueabihf/libc.so.6
> mono#6  0x405330fe in raise () from /lib/arm-linux-gnueabihf/libc.so.6
> mono#7  0x40535956 in abort () from /lib/arm-linux-gnueabihf/libc.so.6
> mono#8  0x00277eaa in monoeg_log_default_handler (log_domain=0x0, log_level=G_LOG_LEVEL_ERROR, message=0x47bb28 "* Assertion at gc.c:867, condition `finalizer_thread_exited' not met\n", unused_data=0x0) at goutput.c:233
> mono#9  0x00277dca in monoeg_g_logv (log_domain=0x0, log_level=G_LOG_LEVEL_ERROR, format=0x3089b8 "* Assertion at %s:%d, condition `%s' not met\n", args=...) at goutput.c:113
> mono#10 0x00277e32 in monoeg_assertion_message (format=0x3089b8 "* Assertion at %s:%d, condition `%s' not met\n") at goutput.c:133
> mono#11 0x001ca786 in mono_gc_cleanup () at gc.c:867
> mono#12 0x001c1d24 in mono_runtime_cleanup (domain=0x37a348) at appdomain.c:356
> mono#13 0x0001dec0 in mini_cleanup (domain=0x37a348) at mini-runtime.c:3560
> mono#14 0x000a672c in mono_main (argc=5, argv=0x358098) at driver.c:2065
> mono#15 0x00017c4e in mono_main_with_options (argc=5, argv=0x358098) at main.c:20
> mono#16 0x00017c7e in main (argc=4, argv=0xbed591b4) at main.c:53

=================================================================
Got a SIGABRT while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries
used by your application.
=================================================================
luhenry added a commit that referenced this pull request Aug 30, 2016
We would previously observe the following crash:

```
ludovic-laptop :: ~/Xamarin/mono ‹16c07b5› » (cd tools/pedump && MONO_PATH=../../mcs/class/lib/net_4_x lldb -- ./pedump --verify metadata,code ../.././mono/tests/xdomain-threads.exe)
(lldb) target create "./pedump"
Current executable set to './pedump' (x86_64).
(lldb) settings set -- target.run-args  "--verify" "metadata,code" "../.././mono/tests/xdomain-threads.exe"
(lldb) r
Process 14407 launched: './pedump' (x86_64)
mono_os_mutex_lock: pthread_mutex_lock failed with "Invalid argument" (22)
Process 14407 stopped
* thread #1: tid = 0x27c9715, 0x00007fff93cfcf06 libsystem_kernel.dylib`__pthread_kill + 10, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
    frame #0: 0x00007fff93cfcf06 libsystem_kernel.dylib`__pthread_kill + 10
	libsystem_kernel.dylib`__pthread_kill:
	->  0x7fff93cfcf06 <+10>: jae    0x7fff93cfcf10            ; <+20>
	    0x7fff93cfcf08 <+12>: movq   %rax, %rdi
        0x7fff93cfcf0b <+15>: jmp    0x7fff93cf77cd            ; cerror_nocancel
	    0x7fff93cfcf10 <+20>: retq
(lldb) bt
* thread #1: tid = 0x27c9715, 0x00007fff93cfcf06 libsystem_kernel.dylib`__pthread_kill + 10, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
  * frame #0: 0x00007fff93cfcf06 libsystem_kernel.dylib`__pthread_kill + 10
    frame #1: 0x00007fff8b9b74ec libsystem_pthread.dylib`pthread_kill + 90
	frame #2: 0x00007fff908d56e7 libsystem_c.dylib`abort + 129
	frame #3: 0x000000010022da6a pedump`monoeg_log_default_handler(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, message="mono_os_mutex_lock: pthread_mutex_lock failed with \"Invalid argument\" (22)", unused_data=0x0000000000000000) + 202 at goutput.c:231
	frame #4: 0x000000010022d98d pedump`monoeg_g_logv(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, format="%s: pthread_mutex_lock failed with \"%s\" (%d)", args=0x00007fff5fbff4a0) + 109 at goutput.c:111
	frame #5: 0x000000010022dbd9 pedump`monoeg_g_log(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, format="%s: pthread_mutex_lock failed with \"%s\" (%d)") + 361 at goutput.c:121
	frame #6: 0x000000010022301e pedump`mono_os_mutex_lock(mutex=0x00000001002ec630) + 110 at mono-os-mutex.h:98
	frame #7: 0x0000000100223a66 pedump`mono_w32handle_new(type=MONO_W32HANDLE_PROCESS, handle_specific=0x00007fff5fbff540) + 246 at w32handle.c:440
	frame #8: 0x00000001001ef8bb pedump`_wapi_processes_init + 123 at processes.c:1149
	frame #9: 0x00000001001fbcc3 pedump`wapi_init + 19 at wapi.c:23
	frame #10: 0x0000000100116486 pedump`mono_init_internal(filename="pedump", exe_filename=0x0000000000000000, runtime_version="v4.0.30319") + 102 at domain.c:528
	frame #11: 0x0000000100117124 pedump`mono_init_version(domain_name="pedump", version="v4.0.30319") + 36 at domain.c:868
	frame #12: 0x0000000100001496 pedump`verify_image_file(fname="../.././mono/tests/xdomain-threads.exe") + 678 at pedump.c:466
	frame #13: 0x0000000100000f87 pedump`main(argc=4, argv=0x00007fff5fbff9a0) + 1095 at pedump.c:708
	frame #14: 0x00007fff93e655ad libdyld.dylib`start + 1
```

That would be because the w32handle wouldn't be initialized before calling into `wapi_init` which allocates w32handle.
luhenry added a commit to luhenry/mono that referenced this pull request Feb 23, 2017
We would observe crashes like the following:

```
 * Assertion at mono-threads.c:1009, condition `mono_thread_info_run_state (info) == STATE_ASYNC_SUSPENDED' not met

 Debug info from gdb:

 [New LWP 26793]
 [New LWP 26792]
 [Thread debugging using libthread_db enabled]
 Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
 0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0
   Id   Target Id         Frame
   3    Thread 0x2b0ff3e6c700 (LWP 26792) "SGen worker" 0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
   2    Thread 0x2b0ff633e700 (LWP 26793) "Finalizer" 0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 * 1    Thread 0x2b0ff2b67c40 (LWP 26780) "mono" 0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0

 Thread 3 (Thread 0x2b0ff3e6c700 (LWP 26792)):
 #0  0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 #1  0x0000000000661bdf in mono_os_cond_wait (mutex=0x9dee40 <lock>, cond=0x9dee00 <work_cond>) at ../../mono/utils/mono-os-mutex.h:146
 #2  thread_func (thread_data=0x2b0ff2bcb008) at sgen-thread-pool.c:129
 #3  0x00002b0ff347a182 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
 #4  0x00002b0ff39a130d in clone () from /lib/x86_64-linux-gnu/libc.so.6

 Thread 2 (Thread 0x2b0ff633e700 (LWP 26793)):
 #0  0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 #1  0x00000000005caff3 in mono_os_cond_wait (mutex=<optimized out>, cond=<optimized out>) at ../../mono/utils/mono-os-mutex.h:146
 #2  mono_coop_cond_wait (mutex=<optimized out>, cond=<optimized out>) at ../../mono/utils/mono-coop-mutex.h:87
 #3  mono_threadpool_io_remove_socket (fd=134239440) at threadpool-io.c:628
 #4  0x00000000005ae4f4 in ves_icall_System_Net_Sockets_Socket_Close_internal (sock=42, werror=<optimized out>) at w32socket.c:708
 mono#5  0x0000000041e8101f in ?? ()
 mono#6  0x00002b1014abe070 in ?? ()
 mono#7  0x0000000001615860 in ?? ()
 mono#8  0x0000000001615860 in ?? ()
 mono#9  0x0000000000000000 in ?? ()

 Thread 1 (Thread 0x2b0ff2b67c40 (LWP 26780)):
 #0  0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0
 #1  0x00000000004ac5e6 in mono_handle_native_crash (signal=<optimized out>, ctx=<optimized out>, info=<optimized out>) at mini-exceptions.c:2557
 #2  <signal handler called>
 #3  0x00002b0ff38dcf79 in raise () from /lib/x86_64-linux-gnu/libc.so.6
 #4  0x00002b0ff38e0388 in abort () from /lib/x86_64-linux-gnu/libc.so.6
 mono#5  0x000000000066b459 in mono_log_write_logfile (log_domain=<optimized out>, level=<optimized out>, hdr=<optimized out>, message=<optimized out>) at mono-log-common.c:137
 mono#6  0x00000000006805e0 in monoeg_g_logv (log_domain=log_domain@entry=0x0, log_level=log_level@entry=G_LOG_LEVEL_ERROR, format=<optimized out>, args=args@entry=0x7ffc7324ea78) at goutput.c:115
 mono#7  0x0000000000680736 in monoeg_assertion_message (format=<optimized out>) at goutput.c:135
 mono#8  0x00000000006759b8 in mono_thread_info_setup_async_call (info=info@entry=0x2b0ff80008c0, target_func=target_func@entry=0x5bac20 <suspend_for_shutdown_async_call>, user_data=user_data@entry=0x0) at mono-threads.c:1009
 mono#9  0x00000000005bad50 in suspend_for_shutdown_critical (info=info@entry=0x2b0ff80008c0, unused=unused@entry=0x0) at threads.c:5019
 mono#10 0x00000000006763ae in mono_thread_info_safe_suspend_and_run (id=47347555100416, interrupt_kernel=interrupt_kernel@entry=0, callback=callback@entry=0x5bad40 <suspend_for_shutdown_critical>, user_data=user_data@entry=0x0) at mono-threads.c:979
 mono#11 0x00000000005c2e71 in mono_thread_internal_suspend_for_shutdown (thread=<optimized out>) at threads.c:5028
 mono#12 0x00000000005e9100 in mono_gc_cleanup () at gc.c:1015
 mono#13 0x00000000005e108e in mono_runtime_cleanup (domain=domain@entry=0x1615860) at appdomain.c:423
 mono#14 0x00000000004228cb in mini_cleanup (domain=0x1615860) at mini-runtime.c:4111
 mono#15 0x000000000047b99f in mono_main (argc=10, argv=<optimized out>) at driver.c:2167
 mono#16 0x00000000004200db in mono_main_with_options (argv=0x7ffc7324ef68, argc=10) at main.c:45
 mono#17 main (argc=10, argv=0x7ffc7324ef68) at main.c:338

 =================================================================
 Got a SIGABRT while executing native code. This usually indicates
 a fatal error in the mono runtime or one of the native libraries
 used by your application.
 =================================================================
```
luhenry added a commit that referenced this pull request Feb 24, 2017
We would observe crashes like the following:

```
 * Assertion at mono-threads.c:1009, condition `mono_thread_info_run_state (info) == STATE_ASYNC_SUSPENDED' not met

 Debug info from gdb:

 [New LWP 26793]
 [New LWP 26792]
 [Thread debugging using libthread_db enabled]
 Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
 0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0
   Id   Target Id         Frame
   3    Thread 0x2b0ff3e6c700 (LWP 26792) "SGen worker" 0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
   2    Thread 0x2b0ff633e700 (LWP 26793) "Finalizer" 0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 * 1    Thread 0x2b0ff2b67c40 (LWP 26780) "mono" 0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0

 Thread 3 (Thread 0x2b0ff3e6c700 (LWP 26792)):
 #0  0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 #1  0x0000000000661bdf in mono_os_cond_wait (mutex=0x9dee40 <lock>, cond=0x9dee00 <work_cond>) at ../../mono/utils/mono-os-mutex.h:146
 #2  thread_func (thread_data=0x2b0ff2bcb008) at sgen-thread-pool.c:129
 #3  0x00002b0ff347a182 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
 #4  0x00002b0ff39a130d in clone () from /lib/x86_64-linux-gnu/libc.so.6

 Thread 2 (Thread 0x2b0ff633e700 (LWP 26793)):
 #0  0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 #1  0x00000000005caff3 in mono_os_cond_wait (mutex=<optimized out>, cond=<optimized out>) at ../../mono/utils/mono-os-mutex.h:146
 #2  mono_coop_cond_wait (mutex=<optimized out>, cond=<optimized out>) at ../../mono/utils/mono-coop-mutex.h:87
 #3  mono_threadpool_io_remove_socket (fd=134239440) at threadpool-io.c:628
 #4  0x00000000005ae4f4 in ves_icall_System_Net_Sockets_Socket_Close_internal (sock=42, werror=<optimized out>) at w32socket.c:708
 #5  0x0000000041e8101f in ?? ()
 #6  0x00002b1014abe070 in ?? ()
 #7  0x0000000001615860 in ?? ()
 #8  0x0000000001615860 in ?? ()
 #9  0x0000000000000000 in ?? ()

 Thread 1 (Thread 0x2b0ff2b67c40 (LWP 26780)):
 #0  0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0
 #1  0x00000000004ac5e6 in mono_handle_native_crash (signal=<optimized out>, ctx=<optimized out>, info=<optimized out>) at mini-exceptions.c:2557
 #2  <signal handler called>
 #3  0x00002b0ff38dcf79 in raise () from /lib/x86_64-linux-gnu/libc.so.6
 #4  0x00002b0ff38e0388 in abort () from /lib/x86_64-linux-gnu/libc.so.6
 #5  0x000000000066b459 in mono_log_write_logfile (log_domain=<optimized out>, level=<optimized out>, hdr=<optimized out>, message=<optimized out>) at mono-log-common.c:137
 #6  0x00000000006805e0 in monoeg_g_logv (log_domain=log_domain@entry=0x0, log_level=log_level@entry=G_LOG_LEVEL_ERROR, format=<optimized out>, args=args@entry=0x7ffc7324ea78) at goutput.c:115
 #7  0x0000000000680736 in monoeg_assertion_message (format=<optimized out>) at goutput.c:135
 #8  0x00000000006759b8 in mono_thread_info_setup_async_call (info=info@entry=0x2b0ff80008c0, target_func=target_func@entry=0x5bac20 <suspend_for_shutdown_async_call>, user_data=user_data@entry=0x0) at mono-threads.c:1009
 #9  0x00000000005bad50 in suspend_for_shutdown_critical (info=info@entry=0x2b0ff80008c0, unused=unused@entry=0x0) at threads.c:5019
 #10 0x00000000006763ae in mono_thread_info_safe_suspend_and_run (id=47347555100416, interrupt_kernel=interrupt_kernel@entry=0, callback=callback@entry=0x5bad40 <suspend_for_shutdown_critical>, user_data=user_data@entry=0x0) at mono-threads.c:979
 #11 0x00000000005c2e71 in mono_thread_internal_suspend_for_shutdown (thread=<optimized out>) at threads.c:5028
 #12 0x00000000005e9100 in mono_gc_cleanup () at gc.c:1015
 #13 0x00000000005e108e in mono_runtime_cleanup (domain=domain@entry=0x1615860) at appdomain.c:423
 #14 0x00000000004228cb in mini_cleanup (domain=0x1615860) at mini-runtime.c:4111
 #15 0x000000000047b99f in mono_main (argc=10, argv=<optimized out>) at driver.c:2167
 #16 0x00000000004200db in mono_main_with_options (argv=0x7ffc7324ef68, argc=10) at main.c:45
 #17 main (argc=10, argv=0x7ffc7324ef68) at main.c:338

 =================================================================
 Got a SIGABRT while executing native code. This usually indicates
 a fatal error in the mono runtime or one of the native libraries
 used by your application.
 =================================================================
```
luhenry added a commit to luhenry/mono that referenced this pull request Mar 8, 2017
We would observe crashes like the following:

```
 * Assertion at mono-threads.c:1009, condition `mono_thread_info_run_state (info) == STATE_ASYNC_SUSPENDED' not met

 Debug info from gdb:

 [New LWP 26793]
 [New LWP 26792]
 [Thread debugging using libthread_db enabled]
 Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
 0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0
   Id   Target Id         Frame
   3    Thread 0x2b0ff3e6c700 (LWP 26792) "SGen worker" 0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
   2    Thread 0x2b0ff633e700 (LWP 26793) "Finalizer" 0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 * 1    Thread 0x2b0ff2b67c40 (LWP 26780) "mono" 0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0

 Thread 3 (Thread 0x2b0ff3e6c700 (LWP 26792)):
 #0  0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 #1  0x0000000000661bdf in mono_os_cond_wait (mutex=0x9dee40 <lock>, cond=0x9dee00 <work_cond>) at ../../mono/utils/mono-os-mutex.h:146
 #2  thread_func (thread_data=0x2b0ff2bcb008) at sgen-thread-pool.c:129
 #3  0x00002b0ff347a182 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
 #4  0x00002b0ff39a130d in clone () from /lib/x86_64-linux-gnu/libc.so.6

 Thread 2 (Thread 0x2b0ff633e700 (LWP 26793)):
 #0  0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 #1  0x00000000005caff3 in mono_os_cond_wait (mutex=<optimized out>, cond=<optimized out>) at ../../mono/utils/mono-os-mutex.h:146
 #2  mono_coop_cond_wait (mutex=<optimized out>, cond=<optimized out>) at ../../mono/utils/mono-coop-mutex.h:87
 #3  mono_threadpool_io_remove_socket (fd=134239440) at threadpool-io.c:628
 #4  0x00000000005ae4f4 in ves_icall_System_Net_Sockets_Socket_Close_internal (sock=42, werror=<optimized out>) at w32socket.c:708
 mono#5  0x0000000041e8101f in ?? ()
 mono#6  0x00002b1014abe070 in ?? ()
 mono#7  0x0000000001615860 in ?? ()
 mono#8  0x0000000001615860 in ?? ()
 mono#9  0x0000000000000000 in ?? ()

 Thread 1 (Thread 0x2b0ff2b67c40 (LWP 26780)):
 #0  0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0
 #1  0x00000000004ac5e6 in mono_handle_native_crash (signal=<optimized out>, ctx=<optimized out>, info=<optimized out>) at mini-exceptions.c:2557
 #2  <signal handler called>
 #3  0x00002b0ff38dcf79 in raise () from /lib/x86_64-linux-gnu/libc.so.6
 #4  0x00002b0ff38e0388 in abort () from /lib/x86_64-linux-gnu/libc.so.6
 mono#5  0x000000000066b459 in mono_log_write_logfile (log_domain=<optimized out>, level=<optimized out>, hdr=<optimized out>, message=<optimized out>) at mono-log-common.c:137
 mono#6  0x00000000006805e0 in monoeg_g_logv (log_domain=log_domain@entry=0x0, log_level=log_level@entry=G_LOG_LEVEL_ERROR, format=<optimized out>, args=args@entry=0x7ffc7324ea78) at goutput.c:115
 mono#7  0x0000000000680736 in monoeg_assertion_message (format=<optimized out>) at goutput.c:135
 mono#8  0x00000000006759b8 in mono_thread_info_setup_async_call (info=info@entry=0x2b0ff80008c0, target_func=target_func@entry=0x5bac20 <suspend_for_shutdown_async_call>, user_data=user_data@entry=0x0) at mono-threads.c:1009
 mono#9  0x00000000005bad50 in suspend_for_shutdown_critical (info=info@entry=0x2b0ff80008c0, unused=unused@entry=0x0) at threads.c:5019
 mono#10 0x00000000006763ae in mono_thread_info_safe_suspend_and_run (id=47347555100416, interrupt_kernel=interrupt_kernel@entry=0, callback=callback@entry=0x5bad40 <suspend_for_shutdown_critical>, user_data=user_data@entry=0x0) at mono-threads.c:979
 mono#11 0x00000000005c2e71 in mono_thread_internal_suspend_for_shutdown (thread=<optimized out>) at threads.c:5028
 mono#12 0x00000000005e9100 in mono_gc_cleanup () at gc.c:1015
 mono#13 0x00000000005e108e in mono_runtime_cleanup (domain=domain@entry=0x1615860) at appdomain.c:423
 mono#14 0x00000000004228cb in mini_cleanup (domain=0x1615860) at mini-runtime.c:4111
 mono#15 0x000000000047b99f in mono_main (argc=10, argv=<optimized out>) at driver.c:2167
 mono#16 0x00000000004200db in mono_main_with_options (argv=0x7ffc7324ef68, argc=10) at main.c:45
 mono#17 main (argc=10, argv=0x7ffc7324ef68) at main.c:338

 =================================================================
 Got a SIGABRT while executing native code. This usually indicates
 a fatal error in the mono runtime or one of the native libraries
 used by your application.
 =================================================================
```
luhenry added a commit that referenced this pull request Mar 9, 2017
We would observe crashes like the following:

```
 * Assertion at mono-threads.c:1009, condition `mono_thread_info_run_state (info) == STATE_ASYNC_SUSPENDED' not met

 Debug info from gdb:

 [New LWP 26793]
 [New LWP 26792]
 [Thread debugging using libthread_db enabled]
 Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
 0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0
   Id   Target Id         Frame
   3    Thread 0x2b0ff3e6c700 (LWP 26792) "SGen worker" 0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
   2    Thread 0x2b0ff633e700 (LWP 26793) "Finalizer" 0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 * 1    Thread 0x2b0ff2b67c40 (LWP 26780) "mono" 0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0

 Thread 3 (Thread 0x2b0ff3e6c700 (LWP 26792)):
 #0  0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 #1  0x0000000000661bdf in mono_os_cond_wait (mutex=0x9dee40 <lock>, cond=0x9dee00 <work_cond>) at ../../mono/utils/mono-os-mutex.h:146
 #2  thread_func (thread_data=0x2b0ff2bcb008) at sgen-thread-pool.c:129
 #3  0x00002b0ff347a182 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
 #4  0x00002b0ff39a130d in clone () from /lib/x86_64-linux-gnu/libc.so.6

 Thread 2 (Thread 0x2b0ff633e700 (LWP 26793)):
 #0  0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 #1  0x00000000005caff3 in mono_os_cond_wait (mutex=<optimized out>, cond=<optimized out>) at ../../mono/utils/mono-os-mutex.h:146
 #2  mono_coop_cond_wait (mutex=<optimized out>, cond=<optimized out>) at ../../mono/utils/mono-coop-mutex.h:87
 #3  mono_threadpool_io_remove_socket (fd=134239440) at threadpool-io.c:628
 #4  0x00000000005ae4f4 in ves_icall_System_Net_Sockets_Socket_Close_internal (sock=42, werror=<optimized out>) at w32socket.c:708
 #5  0x0000000041e8101f in ?? ()
 #6  0x00002b1014abe070 in ?? ()
 #7  0x0000000001615860 in ?? ()
 #8  0x0000000001615860 in ?? ()
 #9  0x0000000000000000 in ?? ()

 Thread 1 (Thread 0x2b0ff2b67c40 (LWP 26780)):
 #0  0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0
 #1  0x00000000004ac5e6 in mono_handle_native_crash (signal=<optimized out>, ctx=<optimized out>, info=<optimized out>) at mini-exceptions.c:2557
 #2  <signal handler called>
 #3  0x00002b0ff38dcf79 in raise () from /lib/x86_64-linux-gnu/libc.so.6
 #4  0x00002b0ff38e0388 in abort () from /lib/x86_64-linux-gnu/libc.so.6
 #5  0x000000000066b459 in mono_log_write_logfile (log_domain=<optimized out>, level=<optimized out>, hdr=<optimized out>, message=<optimized out>) at mono-log-common.c:137
 #6  0x00000000006805e0 in monoeg_g_logv (log_domain=log_domain@entry=0x0, log_level=log_level@entry=G_LOG_LEVEL_ERROR, format=<optimized out>, args=args@entry=0x7ffc7324ea78) at goutput.c:115
 #7  0x0000000000680736 in monoeg_assertion_message (format=<optimized out>) at goutput.c:135
 #8  0x00000000006759b8 in mono_thread_info_setup_async_call (info=info@entry=0x2b0ff80008c0, target_func=target_func@entry=0x5bac20 <suspend_for_shutdown_async_call>, user_data=user_data@entry=0x0) at mono-threads.c:1009
 #9  0x00000000005bad50 in suspend_for_shutdown_critical (info=info@entry=0x2b0ff80008c0, unused=unused@entry=0x0) at threads.c:5019
 #10 0x00000000006763ae in mono_thread_info_safe_suspend_and_run (id=47347555100416, interrupt_kernel=interrupt_kernel@entry=0, callback=callback@entry=0x5bad40 <suspend_for_shutdown_critical>, user_data=user_data@entry=0x0) at mono-threads.c:979
 #11 0x00000000005c2e71 in mono_thread_internal_suspend_for_shutdown (thread=<optimized out>) at threads.c:5028
 #12 0x00000000005e9100 in mono_gc_cleanup () at gc.c:1015
 #13 0x00000000005e108e in mono_runtime_cleanup (domain=domain@entry=0x1615860) at appdomain.c:423
 #14 0x00000000004228cb in mini_cleanup (domain=0x1615860) at mini-runtime.c:4111
 #15 0x000000000047b99f in mono_main (argc=10, argv=<optimized out>) at driver.c:2167
 #16 0x00000000004200db in mono_main_with_options (argv=0x7ffc7324ef68, argc=10) at main.c:45
 #17 main (argc=10, argv=0x7ffc7324ef68) at main.c:338

 =================================================================
 Got a SIGABRT while executing native code. This usually indicates
 a fatal error in the mono runtime or one of the native libraries
 used by your application.
 =================================================================
```
lewurm added a commit to lewurm/mono that referenced this pull request Mar 17, 2017
```
(lldb) monobt
* thread #1
  * frame #0: 0x00000001001b236e mono-sgen`interp_transform_call(td=0x00007fff5fbfd080, method=0x0000000100915a90, target_method=0x0000000000000000, domain=0x000000010090b741
    frame #1: 0x00000001001a1c2e mono-sgen`generate(method=0x0000000100915a90, rtm=0x000000010382ac70, is_bb_start="\x01", generic_context=0x0000000100915ad0) + 9454 at tran8
    transforming TestMonoAsyncGenerics::AsyncWithAwait || frame #2: 0x000000010019f553 mono-sgen`mono_interp_transform_method(runtime_method=0x000000010382ac70, context=0x004
    TestMonoAsyncGenerics::AsyncWithAwait @ 0  || frame mono#3: 0x000000010018a178 mono-sgen`ves_exec_method_with_context(frame=0x00007fff5fbfe290, context=0x00007fff5fbfe3a8) +9
    TestMonoAsyncGenerics::Main @ 12 "pop" || frame mono#4: 0x000000010018b4b1 mono-sgen`ves_exec_method_with_context(frame=0x00007fff5fbfe420, context=0x00007fff5fbfe3a8) + 5081
    frame mono#5: 0x0000000100189e43 mono-sgen`mono_interp_runtime_invoke(method=0x000000010090ce38, obj=0x0000000000000000, params=0x00007fff5fbfea40, exc=0x0000000000000000, e0
    frame mono#6: 0x00000001000164a2 mono-sgen`mono_jit_runtime_invoke(method=0x000000010090ce38, obj=0x0000000000000000, params=0x00007fff5fbfea40, exc=0x0000000000000000, erro1
    frame mono#7: 0x000000010038b2b5 mono-sgen`do_runtime_invoke(method=0x000000010090ce38, obj=0x0000000000000000, params=0x00007fff5fbfea40, exc=0x0000000000000000, error=0x002
    frame mono#8: 0x0000000100384e97 mono-sgen`mono_runtime_invoke_checked(method=0x000000010090ce38, obj=0x0000000000000000, params=0x00007fff5fbfea40, error=0x00007fff5fbfeb000
    frame mono#9: 0x000000010038f335 mono-sgen`do_exec_main_checked(method=0x000000010090ce38, args=0x00000001020003c8, error=0x00007fff5fbfeb00) + 197 at object.c:4672
    frame mono#10: 0x000000010038dd5c mono-sgen`mono_runtime_exec_main_checked(method=0x000000010090ce38, args=0x00000001020003c8, error=0x00007fff5fbfeb00) + 76 at object.c:4773
    frame mono#11: 0x000000010038ddbf mono-sgen`mono_runtime_run_main_checked(method=0x000000010090ce38, argc=1, argv=0x00007fff5fbfef68, error=0x00007fff5fbfeb00) + 79 at objec2
    frame mono#12: 0x00000001000d9a33 mono-sgen`mono_jit_exec(domain=0x000000010090b740, assembly=0x0000000100913610, argc=1, argv=0x00007fff5fbfef68) + 403 at driver.c:1029
    frame mono#13: 0x00000001000dd9da mono-sgen`main_thread_handler(user_data=0x00007fff5fbfeea0) + 538 at driver.c:1098
    frame mono#14: 0x00000001000dc21c mono-sgen`mono_main(argc=3, argv=0x00007fff5fbfef58) + 8636 at driver.c:2163
    frame mono#15: 0x0000000100001b9e mono-sgen`mono_main_with_options(argc=3, argv=0x00007fff5fbfef58) + 46 at main.c:45
    frame mono#16: 0x00000001000012dd mono-sgen`main(argc=3, argv=0x00007fff5fbfef58) + 77 at main.c:338
    frame mono#17: 0x00007fffc2e66255 libdyld.dylib`start + 1
    frame mono#18: 0x00007fffc2e66255 libdyld.dylib`start + 1
```
lewurm added a commit that referenced this pull request Mar 18, 2017
```
(lldb) monobt
* thread #1
  * frame #0: 0x00000001001b236e mono-sgen`interp_transform_call(td=0x00007fff5fbfd080, method=0x0000000100915a90, target_method=0x0000000000000000, domain=0x000000010090b741
    frame #1: 0x00000001001a1c2e mono-sgen`generate(method=0x0000000100915a90, rtm=0x000000010382ac70, is_bb_start="\x01", generic_context=0x0000000100915ad0) + 9454 at tran8
    transforming TestMonoAsyncGenerics::AsyncWithAwait || frame #2: 0x000000010019f553 mono-sgen`mono_interp_transform_method(runtime_method=0x000000010382ac70, context=0x004
    TestMonoAsyncGenerics::AsyncWithAwait @ 0  || frame #3: 0x000000010018a178 mono-sgen`ves_exec_method_with_context(frame=0x00007fff5fbfe290, context=0x00007fff5fbfe3a8) +9
    TestMonoAsyncGenerics::Main @ 12 "pop" || frame #4: 0x000000010018b4b1 mono-sgen`ves_exec_method_with_context(frame=0x00007fff5fbfe420, context=0x00007fff5fbfe3a8) + 5081
    frame #5: 0x0000000100189e43 mono-sgen`mono_interp_runtime_invoke(method=0x000000010090ce38, obj=0x0000000000000000, params=0x00007fff5fbfea40, exc=0x0000000000000000, e0
    frame #6: 0x00000001000164a2 mono-sgen`mono_jit_runtime_invoke(method=0x000000010090ce38, obj=0x0000000000000000, params=0x00007fff5fbfea40, exc=0x0000000000000000, erro1
    frame #7: 0x000000010038b2b5 mono-sgen`do_runtime_invoke(method=0x000000010090ce38, obj=0x0000000000000000, params=0x00007fff5fbfea40, exc=0x0000000000000000, error=0x002
    frame #8: 0x0000000100384e97 mono-sgen`mono_runtime_invoke_checked(method=0x000000010090ce38, obj=0x0000000000000000, params=0x00007fff5fbfea40, error=0x00007fff5fbfeb000
    frame #9: 0x000000010038f335 mono-sgen`do_exec_main_checked(method=0x000000010090ce38, args=0x00000001020003c8, error=0x00007fff5fbfeb00) + 197 at object.c:4672
    frame #10: 0x000000010038dd5c mono-sgen`mono_runtime_exec_main_checked(method=0x000000010090ce38, args=0x00000001020003c8, error=0x00007fff5fbfeb00) + 76 at object.c:4773
    frame #11: 0x000000010038ddbf mono-sgen`mono_runtime_run_main_checked(method=0x000000010090ce38, argc=1, argv=0x00007fff5fbfef68, error=0x00007fff5fbfeb00) + 79 at objec2
    frame #12: 0x00000001000d9a33 mono-sgen`mono_jit_exec(domain=0x000000010090b740, assembly=0x0000000100913610, argc=1, argv=0x00007fff5fbfef68) + 403 at driver.c:1029
    frame #13: 0x00000001000dd9da mono-sgen`main_thread_handler(user_data=0x00007fff5fbfeea0) + 538 at driver.c:1098
    frame #14: 0x00000001000dc21c mono-sgen`mono_main(argc=3, argv=0x00007fff5fbfef58) + 8636 at driver.c:2163
    frame #15: 0x0000000100001b9e mono-sgen`mono_main_with_options(argc=3, argv=0x00007fff5fbfef58) + 46 at main.c:45
    frame #16: 0x00000001000012dd mono-sgen`main(argc=3, argv=0x00007fff5fbfef58) + 77 at main.c:338
    frame #17: 0x00007fffc2e66255 libdyld.dylib`start + 1
    frame #18: 0x00007fffc2e66255 libdyld.dylib`start + 1
```
akoeplinger added a commit that referenced this pull request Jun 5, 2017
Reverts 5e23a77

It seems to cause a crash during msbuild tests:

```
  xunit -> Microsoft.Build.Engine.UnitTests...
  Stacktrace:

  Native stacktrace:

  	0   mono                                0x0017cad4 mono_handle_native_crash + 308
  	1   mono                                0x001e2b03 sigabrt_signal_handler + 147
  	2   libsystem_platform.dylib            0x920a8deb _sigtramp + 43
  	3   ???                                 0xffffffff 0x0 + 4294967295
  	4   libsystem_c.dylib                   0x940bb27c abort + 155
  	5   mono                                0x0036886d mono_log_write_logfile + 381
  	6   mono                                0x003630d2 structured_log_adapter + 50
  	7   mono                                0x00380d1b monoeg_assertion_message + 107
  	8   mono                                0x0033863d major_scan_object_with_evacuation + 3373
  	9   mono                                0x0033b3d0 drain_gray_stack + 6608
  	10  mono                                0x0032df57 finish_gray_stack + 151
  	11  mono                                0x0032d3c6 major_finish_collection + 118
  	12  mono                                0x00329909 major_do_collection + 169
  	13  mono                                0x003288bd sgen_perform_collection + 605
  	14  mono                                0x0032a90b sgen_gc_collect + 75
  	15  mono                                0x002d5c4d unload_thread_main + 861
  	16  mono                                0x002abb6b start_wrapper + 795
  	17  libsystem_pthread.dylib             0x9ae6d5fb _pthread_body + 144
  	18  libsystem_pthread.dylib             0x9ae6d485 _pthread_struct_init + 0
  	19  libsystem_pthread.dylib             0x9ae72cf2 thread_start + 34

  Debug info from gdb:

  (lldb) command source -s 0 '/tmp/mono-gdb-commands.2tso9f'
  Executing commands in '/tmp/mono-gdb-commands.2tso9f'.
  (lldb) process attach --pid 2037
  2017-06-02 13:07:23.000 lldb[2093:282f] Metadata.framework [Error]: couldn't get the client port
  Process 2037 stopped
  * thread #1, name = 'tid_507', queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
      frame #0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
  libsystem_kernel.dylib`__psynch_cvwait:
  ->  0x923cc7ca <+10>: jae    0x923cc7da                ; <+26>
      0x923cc7cc <+12>: calll  0x923cc7d1                ; <+17>
      0x923cc7d1 <+17>: popl   %edx
      0x923cc7d2 <+18>: movl   0xe0b084f(%edx), %edx

  Executable module set to "/Users/builder/data/lanes/2716/mono-mac-sdk/external/bockbuild/stage/bin/mono".
  Architecture set to: i386-apple-macosx.
  (lldb) thread list
  Process 2037 stopped
  * thread #1: tid = 0x530e96a, 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'tid_507', queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
    thread #2: tid = 0x530e96b, 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
    thread #3: tid = 0x530e96c, 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
    thread #4: tid = 0x530e96d, 0x923c7fb6 libsystem_kernel.dylib`semaphore_wait_trap + 10, name = 'Finalizer'
    thread #5: tid = 0x530e96e, 0x923cd992 libsystem_kernel.dylib`kevent64 + 10, queue = 'com.apple.libdispatch-manager'
    thread #6: tid = 0x530ea26, 0x923ccace libsystem_kernel.dylib`__select + 10, name = 'tid_5a03'
    thread #7: tid = 0x530edf1, 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'tid_4007'
    thread #8: tid = 0x530edf2, 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'Threadpool worker'
    thread #9: tid = 0x530edf3, 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'Threadpool worker'
    thread #10: tid = 0x530edf4, 0x923ccff2 libsystem_kernel.dylib`__wait4 + 10, name = 'Domain unloader'
  (lldb) thread backtrace all
  * thread #1, name = 'tid_507', queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
    * frame #0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
      frame #1: 0x9ae6fd1d libsystem_pthread.dylib`_pthread_cond_wait + 728
      frame #2: 0x9ae71bd9 libsystem_pthread.dylib`pthread_cond_wait$UNIX2003 + 71
      frame #3: 0x00361ea9 mono`mono_os_event_wait_multiple + 505
      frame #4: 0x00361ca5 mono`mono_os_event_wait_one + 53
      frame #5: 0x00376b49 mono`mono_thread_info_wait_one_handle + 41
      frame #6: 0x002d51b5 mono`mono_domain_try_unload + 485
      frame #7: 0x002d4f6a mono`ves_icall_System_AppDomain_InternalUnload + 90
      frame #8: 0x05bf9ee0
      frame #9: 0x018ce01d mscorlib.dll.dylib`System_AppDomain_Unload_System_AppDomain + 45
      frame #10: 0x05bf9d60
      frame #11: 0x05bf9ccc
      frame #12: 0x05bf9d04
      frame #13: 0x05bf9c90
      frame #14: 0x05bf996d
      frame #15: 0x02e7d171
      frame #16: 0x005c26d4
      frame #17: 0x005b6878
      frame #18: 0x005b6b7a
      frame #19: 0x000c38a8 mono`mono_jit_runtime_invoke + 1592
      frame #20: 0x002e43fe mono`do_runtime_invoke + 94
      frame #21: 0x002e7de3 mono`do_exec_main_checked + 147
      frame #22: 0x002e69a5 mono`mono_runtime_run_main_checked + 69
      frame #23: 0x0013b687 mono`mono_jit_exec + 311
      frame #24: 0x0013e2b2 mono`mono_main + 10114
      frame #25: 0x000b22db mono`main + 2011
      frame #26: 0x000b1af5 mono`start + 53
    thread #2, name = 'SGen worker'
      frame #0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
      frame #1: 0x9ae6fd1d libsystem_pthread.dylib`_pthread_cond_wait + 728
      frame #2: 0x9ae71bd9 libsystem_pthread.dylib`pthread_cond_wait$UNIX2003 + 71
      frame #3: 0x0035f0e9 mono`thread_func + 249
      frame #4: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame #5: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame #6: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread #3, name = 'SGen worker'
      frame #0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
      frame #1: 0x9ae6fd1d libsystem_pthread.dylib`_pthread_cond_wait + 728
      frame #2: 0x9ae71bd9 libsystem_pthread.dylib`pthread_cond_wait$UNIX2003 + 71
      frame #3: 0x0035f0e9 mono`thread_func + 249
      frame #4: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame #5: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame #6: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread #4, name = 'Finalizer'
      frame #0: 0x923c7fb6 libsystem_kernel.dylib`semaphore_wait_trap + 10
      frame #1: 0x002dbeb6 mono`finalizer_thread + 278
      frame #2: 0x002abb6b mono`start_wrapper + 795
      frame #3: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame #4: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame #5: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread #5, queue = 'com.apple.libdispatch-manager'
      frame #0: 0x923cd992 libsystem_kernel.dylib`kevent64 + 10
      frame #1: 0x91b5c899 libdispatch.dylib`_dispatch_mgr_invoke + 238
      frame #2: 0x91b5c532 libdispatch.dylib`_dispatch_mgr_thread + 52
    thread #6, name = 'tid_5a03'
      frame #0: 0x923ccace libsystem_kernel.dylib`__select + 10
      frame #1: 0x0036df29 mono`mono_poll + 409
      frame #2: 0x002b482f mono`poll_event_wait + 111
      frame #3: 0x002b345f mono`selector_thread + 1439
      frame #4: 0x002abb6b mono`start_wrapper + 795
      frame #5: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame #6: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame #7: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread #7, name = 'tid_4007'
      frame #0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
      frame #1: 0x9ae6fd1d libsystem_pthread.dylib`_pthread_cond_wait + 728
      frame #2: 0x9ae71c25 libsystem_pthread.dylib`pthread_cond_timedwait$UNIX2003 + 71
      frame #3: 0x003760f3 mono`mono_thread_info_sleep + 979
      frame #4: 0x002b1a86 mono`monitor_thread + 262
      frame #5: 0x002abb6b mono`start_wrapper + 795
      frame #6: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame #7: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame #8: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread #8, name = 'Threadpool worker'
      frame #0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
      frame #1: 0x9ae6fd1d libsystem_pthread.dylib`_pthread_cond_wait + 728
      frame #2: 0x9ae71c25 libsystem_pthread.dylib`pthread_cond_timedwait$UNIX2003 + 71
      frame #3: 0x002b12e0 mono`worker_thread + 1024
      frame #4: 0x002abb6b mono`start_wrapper + 795
      frame #5: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame #6: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame #7: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread #9, name = 'Threadpool worker'
      frame #0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
      frame #1: 0x9ae6fd1d libsystem_pthread.dylib`_pthread_cond_wait + 728
      frame #2: 0x9ae71c25 libsystem_pthread.dylib`pthread_cond_timedwait$UNIX2003 + 71
      frame #3: 0x002b12e0 mono`worker_thread + 1024
      frame #4: 0x002abb6b mono`start_wrapper + 795
      frame #5: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame #6: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame #7: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread #10, name = 'Domain unloader'
      frame #0: 0x923ccff2 libsystem_kernel.dylib`__wait4 + 10
      frame #1: 0x940d9ea5 libsystem_c.dylib`waitpid$UNIX2003 + 48
      frame #2: 0x0017cba7 mono`mono_handle_native_crash + 519
      frame #3: 0x001e2b03 mono`sigabrt_signal_handler + 147
      frame #4: 0x920a8deb libsystem_platform.dylib`_sigtramp + 43
  (lldb) detach
  Process 2037 detached
  (lldb) quit

  =================================================================
  Got a SIGABRT while executing native code. This usually indicates
  a fatal error in the mono runtime or one of the native libraries
  used by your application.
  =================================================================
```
@Rombersoft Rombersoft mentioned this pull request May 8, 2018
alexanderkyte added a commit to alexanderkyte/mono that referenced this pull request Oct 30, 2018
We were previously only setting it from the icall. The icall was
therefore fine, while invocations associated with actual dumps
caused crashes like this:

```

thread mono#10, name = 'Thread Pool Worker'
    frame #0: 0x00007fff978dac22 libsystem_kernel.dylib`__psynch_mutexwait + 10
    frame mono#1: 0x00007fff979c5dfa libsystem_pthread.dylib`_pthread_mutex_lock_wait + 100
    frame mono#2: 0x00007fff979c3519 libsystem_pthread.dylib`_pthread_mutex_lock_slow + 285
    frame mono#3: 0x0000000108e0d4a9 mono`mono_loader_lock + 73
    frame mono#4: 0x0000000108dc9106 mono`mono_class_create_from_typedef + 182
    frame mono#5: 0x0000000108dc1f2c mono`mono_class_get_checked + 92
    frame mono#6: 0x0000000108e21da2 mono`mono_metadata_parse_type_internal + 1378
    frame mono#7: 0x0000000108e25e11 mono`mono_metadata_parse_mh_full + 1233
    frame mono#8: 0x0000000108ca4f79 mono`mono_debug_add_aot_method + 121
    frame mono#9: 0x0000000108cc6b1e mono`decode_exception_debug_info + 5918
    frame mono#10: 0x0000000108cc5047 mono`mono_aot_find_jit_info + 1367
    frame mono#11: 0x0000000108e082cc mono`mono_jit_info_table_find_internal + 204
    frame mono#12: 0x0000000108cdb035 mono`mini_jit_info_table_find_ext + 69
    frame mono#13: 0x0000000108cdad5c mono`mono_find_jit_info_ext + 124
    frame mono#14: 0x0000000108cdc3a5 mono`unwinder_unwind_frame + 229
    frame mono#15: 0x0000000108cdbade mono`mono_walk_stack_full + 798
    frame mono#16: 0x0000000108cda1a4 mono`mono_summarize_managed_stack + 100
    frame mono#17: 0x0000000108e6dc03 mono`mono_threads_summarize_execute + 1347
    frame mono#18: 0x0000000108e6df88 mono`mono_threads_summarize + 360

```
monojenkins pushed a commit that referenced this pull request Oct 7, 2019
[lldb] use mono_method_full_name helper

Instead of:

```
(lldb) mbt 20
* thread #11
  * frame #0: 0x1bf28f28 libsystem_kernel.dylib`__pthread_kill + 8
    frame #1: 0x1bf9caac libsystem_pthread.dylib`pthread_kill + 300
    frame #2: 0x1be66080 libsystem_c.dylib`abort + 140
    frame #3: 0x024bdfa0 monotouchtest`log_callback(log_domain=0x00000000, log_level="error", message="../../../../../mono/metadata/object.c:1905: Expected GC Unsafe mode but was in STATE_BLOCKING state", fatal=4, user_data=0x00000000) at runtime.m:1251:3
    frame #4: 0x02487f44 monotouchtest`monoeg_g_logv_nofree(log_domain=0x00000000, log_level=G_LOG_LEVEL_ERROR, format=<unavailable>, args=<unavailable>) at goutput.c:149:2 [opt]
    frame #5: 0x02487ee0 monotouchtest`monoeg_g_logv(log_domain=<unavailable>, log_level=<unavailable>, format=<unavailable>, args=<unavailable>) at goutput.c:156:10 [opt]
    frame #6: 0x02487f74 monotouchtest`monoeg_g_log(log_domain=<unavailable>, log_level=<unavailable>, format=<unavailable>) at goutput.c:165:2 [opt]
    frame #7: 0x024694c4 monotouchtest`assert_gc_unsafe_mode(file="../../../../../mono/metadata/object.c", lineno=1905) at checked-build.c:396:3 [opt]
    frame #8: 0x023d2f64 monotouchtest`mono_class_vtable_checked(domain=0x16d64800, klass=0x173c1b98, error=0x194b0ee8) at object.c:1905:2 [opt]
    frame #9: 0x024130a8 monotouchtest`get_current_thread_ptr_for_domain(domain=0x16d64800, thread=0x02db45d0) at threads.c:635:2 [opt]
    frame #10: 0x024119a8 monotouchtest`mono_thread_current at threads.c:2026:23 [opt]
    frame #11: 0x02416998 monotouchtest`mono_thread_interruption_checkpoint_request(bypass_abort_protection=0) at threads.c:5101:35 [opt]
    Messaging::void_objc_msgSendSuper @ 388435850 "calli.nat.fast" || frame #12: 0x024d5de8 monotouchtest`interp_exec_method_full(frame=0x194b11c0, context=<unavailable>, clause_args=<unavailable>, error=<unavailable>) at interp.c:3230:4 [opt]
    ObjCExceptionTest::InvokeManagedExceptionThrower @ 388435752 "vcall" || frame #13: 0x024d64dc monotouchtest`interp_exec_method_full(frame=0x194b1380, context=<unavailable>, clause_args=<unavailable>, error=<unavailable>) at interp.c:3400:4 [opt]
    ExceptionsTest::ManagedExceptionPassthrough @ 388502134 "vcallvirt.fast" || frame #14: 0x024d61c0 monotouchtest`interp_exec_method_full(frame=0x194b14e0, context=<unavailable>, clause_args=<unavailable>, error=<unavailable>) at interp.c:3325:4 [opt]
    Object::runtime_invoke_direct_void__this__ @ 388462550 "vcall" || frame #15: 0x024d64dc monotouchtest`interp_exec_method_full(frame=0x194b1598, context=<unavailable>, clause_args=<unavailable>, error=<unavailable>) at interp.c:3400:4 [opt]
    frame #16: 0x024d46ec monotouchtest`interp_runtime_invoke(method=<unavailable>, obj=0x0302c5f0, params=0x00000000, exc=0x194b166c, error=0x194b18c8) at interp.c:1766:2 [opt]
    frame #17: 0x0232b39c monotouchtest`mono_jit_runtime_invoke(method=0x174fda58, obj=<unavailable>, params=0x00000000, exc=<unavailable>, error=0x194b18c8) at mini-runtime.c:3170:12 [opt]
    frame #18: 0x023d5cc8 monotouchtest`do_runtime_invoke(method=0x174fda58, obj=0x0302c5f0, params=0x00000000, exc=0x00000000, error=0x194b18c8) at object.c:3017:11 [opt]
    frame #19: 0x023d26a0 monotouchtest`mono_runtime_invoke_checked(method=<unavailable>, obj=<unavailable>, params=<unavailable>, error=<unavailable>) at class-getters.h:24:1 [opt] [artificial]
```

It prints now:

```
(lldb) mbt 20
* thread #11
  * frame #0: 0x1bf28f28 libsystem_kernel.dylib`__pthread_kill + 8
    frame #1: 0x1bf9caac libsystem_pthread.dylib`pthread_kill + 300
    frame #2: 0x1be66080 libsystem_c.dylib`abort + 140
    frame #3: 0x024bdfa0 monotouchtest`log_callback(log_domain=0x00000000, log_level="error", message="../../../../../mono/metadata/object.c:1905: Expected GC Unsafe mode but was in STATE_BLOCKING state", fatal=4, user_data=0x00000000) at runtime.m:1251:3
    frame #4: 0x02487f44 monotouchtest`monoeg_g_logv_nofree(log_domain=0x00000000, log_level=G_LOG_LEVEL_ERROR, format=<unavailable>, args=<unavailable>) at goutput.c:149:2 [opt]
    frame #5: 0x02487ee0 monotouchtest`monoeg_g_logv(log_domain=<unavailable>, log_level=<unavailable>, format=<unavailable>, args=<unavailable>) at goutput.c:156:10 [opt]
    frame #6: 0x02487f74 monotouchtest`monoeg_g_log(log_domain=<unavailable>, log_level=<unavailable>, format=<unavailable>) at goutput.c:165:2 [opt]
    frame #7: 0x024694c4 monotouchtest`assert_gc_unsafe_mode(file="../../../../../mono/metadata/object.c", lineno=1905) at checked-build.c:396:3 [opt]
    frame #8: 0x023d2f64 monotouchtest`mono_class_vtable_checked(domain=0x16d64800, klass=0x173c1b98, error=0x194b0ee8) at object.c:1905:2 [opt]
    frame #9: 0x024130a8 monotouchtest`get_current_thread_ptr_for_domain(domain=0x16d64800, thread=0x02db45d0) at threads.c:635:2 [opt]
    frame #10: 0x024119a8 monotouchtest`mono_thread_current at threads.c:2026:23 [opt]
    frame #11: 0x02416998 monotouchtest`mono_thread_interruption_checkpoint_request(bypass_abort_protection=0) at threads.c:5101:35 [opt]
    (wrapper managed-to-native) ApiDefinition.Messaging:void_objc_msgSendSuper (intptr,intptr) @ 388435850 "calli.nat.fast" || frame #12: 0x024d5de8 monotouchtest`interp_exec_method_full(frame=0x194b11c0, context=<unavailable>, clause_args=<unavailable>, error=<unavailable>) at interp.c:3230:4 [opt]
    Bindings.Test.ObjCExceptionTest:InvokeManagedExceptionThrower () @ 388435752 "vcall" || frame #13: 0x024d64dc monotouchtest`interp_exec_method_full(frame=0x194b1380, context=<unavailable>, clause_args=<unavailable>, error=<unavailable>) at interp.c:3400:4 [opt]
    MonoTouchFixtures.ObjCRuntime.ExceptionsTest:ManagedExceptionPassthrough () @ 388502134 "vcallvirt.fast" || frame #14: 0x024d61c0 monotouchtest`interp_exec_method_full(frame=0x194b14e0, context=<unavailable>, clause_args=<unavailable>, error=<unavailable>) at interp.c:3325:4 [opt]
    (wrapper runtime-invoke) object:runtime_invoke_direct_void__this__ (object,intptr,intptr,intptr) @ 388462550 "vcall" || frame #15: 0x024d64dc monotouchtest`interp_exec_method_full(frame=0x194b1598, context=<unavailable>, clause_args=<unavailable>, error=<unavailable>) at interp.c:3400:4 [opt]
    frame #16: 0x024d46ec monotouchtest`interp_runtime_invoke(method=<unavailable>, obj=0x0302c5f0, params=0x00000000, exc=0x194b166c, error=0x194b18c8) at interp.c:1766:2 [opt]
    frame #17: 0x0232b39c monotouchtest`mono_jit_runtime_invoke(method=0x174fda58, obj=<unavailable>, params=0x00000000, exc=<unavailable>, error=0x194b18c8) at mini-runtime.c:3170:12 [opt]
    frame #18: 0x023d5cc8 monotouchtest`do_runtime_invoke(method=0x174fda58, obj=0x0302c5f0, params=0x00000000, exc=0x00000000, error=0x194b18c8) at object.c:3017:11 [opt]
    frame #19: 0x023d26a0 monotouchtest`mono_runtime_invoke_checked(method=<unavailable>, obj=<unavailable>, params=<unavailable>, error=<unavailable>) at class-getters.h:24:1 [opt] [artificial]
```



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lewurm added a commit to lewurm/mono that referenced this pull request Dec 9, 2019
When the debugger tries to suspend all the VM threads, it can happen with cooperative-suspend that it tries to suspend a thread that has previously been attached, but then did a "light" detach (that only unsets the domain). With the domain set to `NULL`, looking up a JitInfo for a given `ip` will result into a crash, but it isn't even necessarily needed for the purpose of suspending a thread.

More details: Consider the following:
```
(lldb) c
error: Process is running.  Use 'process interrupt' to pause execution.
Process 12832 stopped
* thread mono#9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
    frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
   2713         MonoDomain *domain = (MonoDomain *) mono_thread_info_get_suspend_state (info)->unwind_data [MONO_UNWIND_DATA_DOMAIN];
   2714         if (!domain) {
   2715                 /* not attached */
-> 2716                 ji = NULL;
   2717         } else {
   2718                 ji = mono_jit_info_table_find_internal ( domain, MONO_CONTEXT_GET_IP (&mono_thread_info_get_suspend_state (info)->ctx), TRUE, TRUE);
   2719         }
Target 0: (WatchWCSessionAppWatchOSExtension) stopped.
(lldb) bt
* thread mono#9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  * frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
    frame #1: 0x004e177b WatchWCSessionAppWatchOSExtension`mono_thread_info_safe_suspend_and_run(id=0xb0767000, interrupt_kernel=0, callback=(WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical at debugger-agent.c:2708), user_data=0xb04dc718) at mono-threads.c:1358:19
    frame #2: 0x00222799 WatchWCSessionAppWatchOSExtension`notify_thread(key=0x03994508, value=0x81378c00, user_data=0x00000000) at debugger-agent.c:2747:2
    frame mono#3: 0x00355bd8 WatchWCSessionAppWatchOSExtension`mono_g_hash_table_foreach(hash=0x8007b4e0, func=(WatchWCSessionAppWatchOSExtension`notify_thread at debugger-agent.c:2733), user_data=0x00000000) at mono-hash.c:310:4
    frame mono#4: 0x0021e955 WatchWCSessionAppWatchOSExtension`suspend_vm at debugger-agent.c:2844:3
    frame mono#5: 0x00225ff0 WatchWCSessionAppWatchOSExtension`process_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0, il_offset=0, ctx=0x00000000, events=0x805b28e0, suspend_policy=2) at debugger-agent.c:4012:3
    frame mono#6: 0x00227c7c WatchWCSessionAppWatchOSExtension`process_profiler_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0) at debugger-agent.c:4072:2
    frame mono#7: 0x0021b174 WatchWCSessionAppWatchOSExtension`thread_startup(prof=0x00000000, tid=2957889536) at debugger-agent.c:4149:2
    frame mono#8: 0x0037912d WatchWCSessionAppWatchOSExtension`mono_profiler_raise_thread_started(tid=2957889536) at profiler-events.h:103:1
    frame mono#9: 0x003d53da WatchWCSessionAppWatchOSExtension`fire_attach_profiler_events(tid=0xb04dd000) at threads.c:1120:2
    frame mono#10: 0x003d4d83 WatchWCSessionAppWatchOSExtension`mono_thread_attach(domain=0x801750a0) at threads.c:1547:2
    frame mono#11: 0x003df1a1 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop_internal(domain=0x801750a0, cookie=0xb04dcc0c, stackdata=0xb04dcba8) at threads.c:6008:3
    frame mono#12: 0x003df287 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop(domain=0x00000000, dummy=0xb04dcc0c) at threads.c:6045:9
    frame mono#13: 0x005034b8 WatchWCSessionAppWatchOSExtension`::xamarin_switch_gchandle(self=0x80762c20, to_weak=false) at runtime.m:1805:2
    frame mono#14: 0x005065c1 WatchWCSessionAppWatchOSExtension`::xamarin_retain_trampoline(self=0x80762c20, sel="retain") at trampolines.m:693:2
    frame mono#15: 0x657ea520 libobjc.A.dylib`objc_retain + 64
    frame mono#16: 0x4b4d9caa WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke + 279
    frame mono#17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame mono#18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame mono#19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame mono#20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame mono#21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame mono#22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame mono#23: 0x453cb26e Foundation`____addOperations_block_invoke_4 + 20
    frame mono#24: 0x65de007b libdispatch.dylib`_dispatch_call_block_and_release + 15
    frame mono#25: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono#26: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame mono#27: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame mono#28: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame mono#29: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame mono#30: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame mono#31: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```

Going further, `info` is about this thread:
```
(lldb) p/x *(int *)(((char *) info->node.key) + 0xa0)
(int) $2 = 0x01243f93
(lldb) thread list
Process 12832 stopped
  thread #1: tid = 0x1243ee1, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_303', queue = 'com.apple.main-thread'
  thread #2: tid = 0x1243ee6, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10
  thread mono#3: tid = 0x1243ee7, 0x65f81aea libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
  thread mono#4: tid = 0x1243ee9, 0x65f7e3d2 libsystem_kernel.dylib`semaphore_wait_trap + 10, name = 'Finalizer'
  thread mono#5: tid = 0x1243eea, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10, name = 'Debugger agent'
  thread mono#6: tid = 0x1243f1d, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'com.apple.uikit.eventfetch-thread'
  thread mono#8: tid = 0x1243f93, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
* thread mono#9: tid = 0x12443a9, 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  thread mono#10: tid = 0x1244581, 0x65f7fd32 libsystem_kernel.dylib`__workq_kernreturn + 10
(lldb) thread select 8
* thread mono#8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
    frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
libsystem_kernel.dylib`mach_msg_trap:
->  0x65f7e396 <+10>: retl
    0x65f7e397 <+11>: nop

libsystem_kernel.dylib`mach_msg_overwrite_trap:
    0x65f7e398 <+0>:  movl   $0xffffffe0, %eax         ; imm = 0xFFFFFFE0
    0x65f7e39d <+5>:  calll  0x65f85f44                ; _sysenter_trap
(lldb) bt
* thread mono#8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
  * frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
    frame #1: 0x65f7e8ff libsystem_kernel.dylib`mach_msg + 47
    frame #2: 0x66079679 libxpc.dylib`_xpc_send_serializer + 104
    frame mono#3: 0x660794da libxpc.dylib`_xpc_pipe_simpleroutine + 80
    frame mono#4: 0x66079852 libxpc.dylib`xpc_pipe_simpleroutine + 43
    frame mono#5: 0x66043a8f libsystem_trace.dylib`___os_activity_stream_reflect_block_invoke_2 + 30
    frame mono#6: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono#7: 0x65de3d71 libdispatch.dylib`_dispatch_block_invoke_direct + 257
    frame mono#8: 0x65de3c62 libdispatch.dylib`dispatch_block_perform + 112
    frame mono#9: 0x6604349a libsystem_trace.dylib`_os_activity_stream_reflect + 725
    frame mono#10: 0x6604ef19 libsystem_trace.dylib`_os_log_impl_stream + 468
    frame mono#11: 0x6604e44d libsystem_trace.dylib`_os_log_impl_flatten_and_send + 6410
    frame mono#12: 0x6604cb3b libsystem_trace.dylib`_os_log + 137
    frame mono#13: 0x6604f4aa libsystem_trace.dylib`_os_log_impl + 31
    frame mono#14: 0x4b4eb4e9 WatchConnectivity`WCSerializePayloadDictionary + 393
    frame mono#15: 0x4b4d7c4d WatchConnectivity`-[WCSession onqueue_sendResponseDictionary:identifier:] + 195
    frame mono#16: 0x4b4da435 WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke.411 + 35
    frame mono#17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame mono#18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame mono#19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame mono#20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame mono#21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame mono#22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame mono#23: 0x453cb067 Foundation`____addOperations_block_invoke_2 + 20
    frame mono#24: 0x65dedf49 libdispatch.dylib`_dispatch_block_async_invoke2 + 77
    frame mono#25: 0x65de4461 libdispatch.dylib`_dispatch_block_async_invoke_and_release + 17
    frame mono#26: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono#27: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame mono#28: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame mono#29: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame mono#30: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame mono#31: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame mono#32: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```
which is a thread in a "light" detach state (aka. coop detach), where we only unset the domain:
https://github.com/mono/mono/blob/4cefdcb7ce2d939ee78fb45d1b4913eb3bc064fd/mono/metadata/threads.c#L6084-L6111

Fixes mono#17926
lewurm added a commit that referenced this pull request Dec 10, 2019
When the debugger tries to suspend all the VM threads, it can happen with cooperative-suspend that it tries to suspend a thread that has previously been attached, but then did a "light" detach (that only unsets the domain). With the domain set to `NULL`, looking up a JitInfo for a given `ip` will result into a crash, but it isn't even necessarily needed for the purpose of suspending a thread.

More details: Consider the following:
```
(lldb) c
error: Process is running.  Use 'process interrupt' to pause execution.
Process 12832 stopped
* thread #9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
    frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
   2713         MonoDomain *domain = (MonoDomain *) mono_thread_info_get_suspend_state (info)->unwind_data [MONO_UNWIND_DATA_DOMAIN];
   2714         if (!domain) {
   2715                 /* not attached */
-> 2716                 ji = NULL;
   2717         } else {
   2718                 ji = mono_jit_info_table_find_internal ( domain, MONO_CONTEXT_GET_IP (&mono_thread_info_get_suspend_state (info)->ctx), TRUE, TRUE);
   2719         }
Target 0: (WatchWCSessionAppWatchOSExtension) stopped.
(lldb) bt
* thread #9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  * frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
    frame #1: 0x004e177b WatchWCSessionAppWatchOSExtension`mono_thread_info_safe_suspend_and_run(id=0xb0767000, interrupt_kernel=0, callback=(WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical at debugger-agent.c:2708), user_data=0xb04dc718) at mono-threads.c:1358:19
    frame #2: 0x00222799 WatchWCSessionAppWatchOSExtension`notify_thread(key=0x03994508, value=0x81378c00, user_data=0x00000000) at debugger-agent.c:2747:2
    frame #3: 0x00355bd8 WatchWCSessionAppWatchOSExtension`mono_g_hash_table_foreach(hash=0x8007b4e0, func=(WatchWCSessionAppWatchOSExtension`notify_thread at debugger-agent.c:2733), user_data=0x00000000) at mono-hash.c:310:4
    frame #4: 0x0021e955 WatchWCSessionAppWatchOSExtension`suspend_vm at debugger-agent.c:2844:3
    frame #5: 0x00225ff0 WatchWCSessionAppWatchOSExtension`process_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0, il_offset=0, ctx=0x00000000, events=0x805b28e0, suspend_policy=2) at debugger-agent.c:4012:3
    frame #6: 0x00227c7c WatchWCSessionAppWatchOSExtension`process_profiler_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0) at debugger-agent.c:4072:2
    frame #7: 0x0021b174 WatchWCSessionAppWatchOSExtension`thread_startup(prof=0x00000000, tid=2957889536) at debugger-agent.c:4149:2
    frame #8: 0x0037912d WatchWCSessionAppWatchOSExtension`mono_profiler_raise_thread_started(tid=2957889536) at profiler-events.h:103:1
    frame #9: 0x003d53da WatchWCSessionAppWatchOSExtension`fire_attach_profiler_events(tid=0xb04dd000) at threads.c:1120:2
    frame #10: 0x003d4d83 WatchWCSessionAppWatchOSExtension`mono_thread_attach(domain=0x801750a0) at threads.c:1547:2
    frame #11: 0x003df1a1 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop_internal(domain=0x801750a0, cookie=0xb04dcc0c, stackdata=0xb04dcba8) at threads.c:6008:3
    frame #12: 0x003df287 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop(domain=0x00000000, dummy=0xb04dcc0c) at threads.c:6045:9
    frame #13: 0x005034b8 WatchWCSessionAppWatchOSExtension`::xamarin_switch_gchandle(self=0x80762c20, to_weak=false) at runtime.m:1805:2
    frame #14: 0x005065c1 WatchWCSessionAppWatchOSExtension`::xamarin_retain_trampoline(self=0x80762c20, sel="retain") at trampolines.m:693:2
    frame #15: 0x657ea520 libobjc.A.dylib`objc_retain + 64
    frame #16: 0x4b4d9caa WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke + 279
    frame #17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame #18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame #19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame #20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame #21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame #22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame #23: 0x453cb26e Foundation`____addOperations_block_invoke_4 + 20
    frame #24: 0x65de007b libdispatch.dylib`_dispatch_call_block_and_release + 15
    frame #25: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame #26: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame #27: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame #28: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame #29: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame #30: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame #31: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```

Going further, `info` is about this thread:
```
(lldb) p/x *(int *)(((char *) info->node.key) + 0xa0)
(int) $2 = 0x01243f93
(lldb) thread list
Process 12832 stopped
  thread #1: tid = 0x1243ee1, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_303', queue = 'com.apple.main-thread'
  thread #2: tid = 0x1243ee6, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10
  thread #3: tid = 0x1243ee7, 0x65f81aea libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
  thread #4: tid = 0x1243ee9, 0x65f7e3d2 libsystem_kernel.dylib`semaphore_wait_trap + 10, name = 'Finalizer'
  thread #5: tid = 0x1243eea, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10, name = 'Debugger agent'
  thread #6: tid = 0x1243f1d, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'com.apple.uikit.eventfetch-thread'
  thread #8: tid = 0x1243f93, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
* thread #9: tid = 0x12443a9, 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  thread #10: tid = 0x1244581, 0x65f7fd32 libsystem_kernel.dylib`__workq_kernreturn + 10
(lldb) thread select 8
* thread #8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
    frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
libsystem_kernel.dylib`mach_msg_trap:
->  0x65f7e396 <+10>: retl
    0x65f7e397 <+11>: nop

libsystem_kernel.dylib`mach_msg_overwrite_trap:
    0x65f7e398 <+0>:  movl   $0xffffffe0, %eax         ; imm = 0xFFFFFFE0
    0x65f7e39d <+5>:  calll  0x65f85f44                ; _sysenter_trap
(lldb) bt
* thread #8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
  * frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
    frame #1: 0x65f7e8ff libsystem_kernel.dylib`mach_msg + 47
    frame #2: 0x66079679 libxpc.dylib`_xpc_send_serializer + 104
    frame #3: 0x660794da libxpc.dylib`_xpc_pipe_simpleroutine + 80
    frame #4: 0x66079852 libxpc.dylib`xpc_pipe_simpleroutine + 43
    frame #5: 0x66043a8f libsystem_trace.dylib`___os_activity_stream_reflect_block_invoke_2 + 30
    frame #6: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame #7: 0x65de3d71 libdispatch.dylib`_dispatch_block_invoke_direct + 257
    frame #8: 0x65de3c62 libdispatch.dylib`dispatch_block_perform + 112
    frame #9: 0x6604349a libsystem_trace.dylib`_os_activity_stream_reflect + 725
    frame #10: 0x6604ef19 libsystem_trace.dylib`_os_log_impl_stream + 468
    frame #11: 0x6604e44d libsystem_trace.dylib`_os_log_impl_flatten_and_send + 6410
    frame #12: 0x6604cb3b libsystem_trace.dylib`_os_log + 137
    frame #13: 0x6604f4aa libsystem_trace.dylib`_os_log_impl + 31
    frame #14: 0x4b4eb4e9 WatchConnectivity`WCSerializePayloadDictionary + 393
    frame #15: 0x4b4d7c4d WatchConnectivity`-[WCSession onqueue_sendResponseDictionary:identifier:] + 195
    frame #16: 0x4b4da435 WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke.411 + 35
    frame #17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame #18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame #19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame #20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame #21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame #22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame #23: 0x453cb067 Foundation`____addOperations_block_invoke_2 + 20
    frame #24: 0x65dedf49 libdispatch.dylib`_dispatch_block_async_invoke2 + 77
    frame #25: 0x65de4461 libdispatch.dylib`_dispatch_block_async_invoke_and_release + 17
    frame #26: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame #27: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame #28: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame #29: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame #30: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame #31: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame #32: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```
which is a thread in a "light" detach state (aka. coop detach), where we only unset the domain:
https://github.com/mono/mono/blob/4cefdcb7ce2d939ee78fb45d1b4913eb3bc064fd/mono/metadata/threads.c#L6084-L6111

Fixes #17926
monojenkins pushed a commit to monojenkins/mono that referenced this pull request Dec 10, 2019
When the debugger tries to suspend all the VM threads, it can happen with cooperative-suspend that it tries to suspend a thread that has previously been attached, but then did a "light" detach (that only unsets the domain). With the domain set to `NULL`, looking up a JitInfo for a given `ip` will result into a crash, but it isn't even necessarily needed for the purpose of suspending a thread.

More details: Consider the following:
```
(lldb) c
error: Process is running.  Use 'process interrupt' to pause execution.
Process 12832 stopped
* thread mono#9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
    frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
   2713         MonoDomain *domain = (MonoDomain *) mono_thread_info_get_suspend_state (info)->unwind_data [MONO_UNWIND_DATA_DOMAIN];
   2714         if (!domain) {
   2715                 /* not attached */
-> 2716                 ji = NULL;
   2717         } else {
   2718                 ji = mono_jit_info_table_find_internal ( domain, MONO_CONTEXT_GET_IP (&mono_thread_info_get_suspend_state (info)->ctx), TRUE, TRUE);
   2719         }
Target 0: (WatchWCSessionAppWatchOSExtension) stopped.
(lldb) bt
* thread mono#9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  * frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
    frame mono#1: 0x004e177b WatchWCSessionAppWatchOSExtension`mono_thread_info_safe_suspend_and_run(id=0xb0767000, interrupt_kernel=0, callback=(WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical at debugger-agent.c:2708), user_data=0xb04dc718) at mono-threads.c:1358:19
    frame mono#2: 0x00222799 WatchWCSessionAppWatchOSExtension`notify_thread(key=0x03994508, value=0x81378c00, user_data=0x00000000) at debugger-agent.c:2747:2
    frame mono#3: 0x00355bd8 WatchWCSessionAppWatchOSExtension`mono_g_hash_table_foreach(hash=0x8007b4e0, func=(WatchWCSessionAppWatchOSExtension`notify_thread at debugger-agent.c:2733), user_data=0x00000000) at mono-hash.c:310:4
    frame mono#4: 0x0021e955 WatchWCSessionAppWatchOSExtension`suspend_vm at debugger-agent.c:2844:3
    frame mono#5: 0x00225ff0 WatchWCSessionAppWatchOSExtension`process_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0, il_offset=0, ctx=0x00000000, events=0x805b28e0, suspend_policy=2) at debugger-agent.c:4012:3
    frame mono#6: 0x00227c7c WatchWCSessionAppWatchOSExtension`process_profiler_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0) at debugger-agent.c:4072:2
    frame mono#7: 0x0021b174 WatchWCSessionAppWatchOSExtension`thread_startup(prof=0x00000000, tid=2957889536) at debugger-agent.c:4149:2
    frame mono#8: 0x0037912d WatchWCSessionAppWatchOSExtension`mono_profiler_raise_thread_started(tid=2957889536) at profiler-events.h:103:1
    frame mono#9: 0x003d53da WatchWCSessionAppWatchOSExtension`fire_attach_profiler_events(tid=0xb04dd000) at threads.c:1120:2
    frame mono#10: 0x003d4d83 WatchWCSessionAppWatchOSExtension`mono_thread_attach(domain=0x801750a0) at threads.c:1547:2
    frame mono#11: 0x003df1a1 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop_internal(domain=0x801750a0, cookie=0xb04dcc0c, stackdata=0xb04dcba8) at threads.c:6008:3
    frame mono#12: 0x003df287 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop(domain=0x00000000, dummy=0xb04dcc0c) at threads.c:6045:9
    frame mono#13: 0x005034b8 WatchWCSessionAppWatchOSExtension`::xamarin_switch_gchandle(self=0x80762c20, to_weak=false) at runtime.m:1805:2
    frame mono#14: 0x005065c1 WatchWCSessionAppWatchOSExtension`::xamarin_retain_trampoline(self=0x80762c20, sel="retain") at trampolines.m:693:2
    frame mono#15: 0x657ea520 libobjc.A.dylib`objc_retain + 64
    frame mono#16: 0x4b4d9caa WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke + 279
    frame mono#17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame mono#18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame mono#19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame mono#20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame mono#21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame mono#22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame mono#23: 0x453cb26e Foundation`____addOperations_block_invoke_4 + 20
    frame mono#24: 0x65de007b libdispatch.dylib`_dispatch_call_block_and_release + 15
    frame mono#25: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono#26: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame mono#27: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame mono#28: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame mono#29: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame mono#30: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame mono#31: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```

Going further, `info` is about this thread:
```
(lldb) p/x *(int *)(((char *) info->node.key) + 0xa0)
(int) $2 = 0x01243f93
(lldb) thread list
Process 12832 stopped
  thread mono#1: tid = 0x1243ee1, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_303', queue = 'com.apple.main-thread'
  thread mono#2: tid = 0x1243ee6, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10
  thread mono#3: tid = 0x1243ee7, 0x65f81aea libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
  thread mono#4: tid = 0x1243ee9, 0x65f7e3d2 libsystem_kernel.dylib`semaphore_wait_trap + 10, name = 'Finalizer'
  thread mono#5: tid = 0x1243eea, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10, name = 'Debugger agent'
  thread mono#6: tid = 0x1243f1d, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'com.apple.uikit.eventfetch-thread'
  thread mono#8: tid = 0x1243f93, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
* thread mono#9: tid = 0x12443a9, 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  thread mono#10: tid = 0x1244581, 0x65f7fd32 libsystem_kernel.dylib`__workq_kernreturn + 10
(lldb) thread select 8
* thread mono#8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
    frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
libsystem_kernel.dylib`mach_msg_trap:
->  0x65f7e396 <+10>: retl
    0x65f7e397 <+11>: nop

libsystem_kernel.dylib`mach_msg_overwrite_trap:
    0x65f7e398 <+0>:  movl   $0xffffffe0, %eax         ; imm = 0xFFFFFFE0
    0x65f7e39d <+5>:  calll  0x65f85f44                ; _sysenter_trap
(lldb) bt
* thread mono#8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
  * frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
    frame mono#1: 0x65f7e8ff libsystem_kernel.dylib`mach_msg + 47
    frame mono#2: 0x66079679 libxpc.dylib`_xpc_send_serializer + 104
    frame mono#3: 0x660794da libxpc.dylib`_xpc_pipe_simpleroutine + 80
    frame mono#4: 0x66079852 libxpc.dylib`xpc_pipe_simpleroutine + 43
    frame mono#5: 0x66043a8f libsystem_trace.dylib`___os_activity_stream_reflect_block_invoke_2 + 30
    frame mono#6: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono#7: 0x65de3d71 libdispatch.dylib`_dispatch_block_invoke_direct + 257
    frame mono#8: 0x65de3c62 libdispatch.dylib`dispatch_block_perform + 112
    frame mono#9: 0x6604349a libsystem_trace.dylib`_os_activity_stream_reflect + 725
    frame mono#10: 0x6604ef19 libsystem_trace.dylib`_os_log_impl_stream + 468
    frame mono#11: 0x6604e44d libsystem_trace.dylib`_os_log_impl_flatten_and_send + 6410
    frame mono#12: 0x6604cb3b libsystem_trace.dylib`_os_log + 137
    frame mono#13: 0x6604f4aa libsystem_trace.dylib`_os_log_impl + 31
    frame mono#14: 0x4b4eb4e9 WatchConnectivity`WCSerializePayloadDictionary + 393
    frame mono#15: 0x4b4d7c4d WatchConnectivity`-[WCSession onqueue_sendResponseDictionary:identifier:] + 195
    frame mono#16: 0x4b4da435 WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke.411 + 35
    frame mono#17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame mono#18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame mono#19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame mono#20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame mono#21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame mono#22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame mono#23: 0x453cb067 Foundation`____addOperations_block_invoke_2 + 20
    frame mono#24: 0x65dedf49 libdispatch.dylib`_dispatch_block_async_invoke2 + 77
    frame mono#25: 0x65de4461 libdispatch.dylib`_dispatch_block_async_invoke_and_release + 17
    frame mono#26: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono#27: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame mono#28: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame mono#29: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame mono#30: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame mono#31: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame mono#32: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```
which is a thread in a "light" detach state (aka. coop detach), where we only unset the domain:
https://github.com/mono/mono/blob/4cefdcb7ce2d939ee78fb45d1b4913eb3bc064fd/mono/metadata/threads.c#L6084-L6111

Fixes mono#17926
monojenkins pushed a commit to monojenkins/mono that referenced this pull request Dec 10, 2019
When the debugger tries to suspend all the VM threads, it can happen with cooperative-suspend that it tries to suspend a thread that has previously been attached, but then did a "light" detach (that only unsets the domain). With the domain set to `NULL`, looking up a JitInfo for a given `ip` will result into a crash, but it isn't even necessarily needed for the purpose of suspending a thread.

More details: Consider the following:
```
(lldb) c
error: Process is running.  Use 'process interrupt' to pause execution.
Process 12832 stopped
* thread mono#9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
    frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
   2713         MonoDomain *domain = (MonoDomain *) mono_thread_info_get_suspend_state (info)->unwind_data [MONO_UNWIND_DATA_DOMAIN];
   2714         if (!domain) {
   2715                 /* not attached */
-> 2716                 ji = NULL;
   2717         } else {
   2718                 ji = mono_jit_info_table_find_internal ( domain, MONO_CONTEXT_GET_IP (&mono_thread_info_get_suspend_state (info)->ctx), TRUE, TRUE);
   2719         }
Target 0: (WatchWCSessionAppWatchOSExtension) stopped.
(lldb) bt
* thread mono#9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  * frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
    frame mono#1: 0x004e177b WatchWCSessionAppWatchOSExtension`mono_thread_info_safe_suspend_and_run(id=0xb0767000, interrupt_kernel=0, callback=(WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical at debugger-agent.c:2708), user_data=0xb04dc718) at mono-threads.c:1358:19
    frame mono#2: 0x00222799 WatchWCSessionAppWatchOSExtension`notify_thread(key=0x03994508, value=0x81378c00, user_data=0x00000000) at debugger-agent.c:2747:2
    frame mono#3: 0x00355bd8 WatchWCSessionAppWatchOSExtension`mono_g_hash_table_foreach(hash=0x8007b4e0, func=(WatchWCSessionAppWatchOSExtension`notify_thread at debugger-agent.c:2733), user_data=0x00000000) at mono-hash.c:310:4
    frame mono#4: 0x0021e955 WatchWCSessionAppWatchOSExtension`suspend_vm at debugger-agent.c:2844:3
    frame mono#5: 0x00225ff0 WatchWCSessionAppWatchOSExtension`process_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0, il_offset=0, ctx=0x00000000, events=0x805b28e0, suspend_policy=2) at debugger-agent.c:4012:3
    frame mono#6: 0x00227c7c WatchWCSessionAppWatchOSExtension`process_profiler_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0) at debugger-agent.c:4072:2
    frame mono#7: 0x0021b174 WatchWCSessionAppWatchOSExtension`thread_startup(prof=0x00000000, tid=2957889536) at debugger-agent.c:4149:2
    frame mono#8: 0x0037912d WatchWCSessionAppWatchOSExtension`mono_profiler_raise_thread_started(tid=2957889536) at profiler-events.h:103:1
    frame mono#9: 0x003d53da WatchWCSessionAppWatchOSExtension`fire_attach_profiler_events(tid=0xb04dd000) at threads.c:1120:2
    frame mono#10: 0x003d4d83 WatchWCSessionAppWatchOSExtension`mono_thread_attach(domain=0x801750a0) at threads.c:1547:2
    frame mono#11: 0x003df1a1 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop_internal(domain=0x801750a0, cookie=0xb04dcc0c, stackdata=0xb04dcba8) at threads.c:6008:3
    frame mono#12: 0x003df287 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop(domain=0x00000000, dummy=0xb04dcc0c) at threads.c:6045:9
    frame mono#13: 0x005034b8 WatchWCSessionAppWatchOSExtension`::xamarin_switch_gchandle(self=0x80762c20, to_weak=false) at runtime.m:1805:2
    frame mono#14: 0x005065c1 WatchWCSessionAppWatchOSExtension`::xamarin_retain_trampoline(self=0x80762c20, sel="retain") at trampolines.m:693:2
    frame mono#15: 0x657ea520 libobjc.A.dylib`objc_retain + 64
    frame mono#16: 0x4b4d9caa WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke + 279
    frame mono#17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame mono#18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame mono#19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame mono#20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame mono#21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame mono#22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame mono#23: 0x453cb26e Foundation`____addOperations_block_invoke_4 + 20
    frame mono#24: 0x65de007b libdispatch.dylib`_dispatch_call_block_and_release + 15
    frame mono#25: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono#26: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame mono#27: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame mono#28: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame mono#29: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame mono#30: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame mono#31: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```

Going further, `info` is about this thread:
```
(lldb) p/x *(int *)(((char *) info->node.key) + 0xa0)
(int) $2 = 0x01243f93
(lldb) thread list
Process 12832 stopped
  thread mono#1: tid = 0x1243ee1, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_303', queue = 'com.apple.main-thread'
  thread mono#2: tid = 0x1243ee6, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10
  thread mono#3: tid = 0x1243ee7, 0x65f81aea libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
  thread mono#4: tid = 0x1243ee9, 0x65f7e3d2 libsystem_kernel.dylib`semaphore_wait_trap + 10, name = 'Finalizer'
  thread mono#5: tid = 0x1243eea, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10, name = 'Debugger agent'
  thread mono#6: tid = 0x1243f1d, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'com.apple.uikit.eventfetch-thread'
  thread mono#8: tid = 0x1243f93, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
* thread mono#9: tid = 0x12443a9, 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  thread mono#10: tid = 0x1244581, 0x65f7fd32 libsystem_kernel.dylib`__workq_kernreturn + 10
(lldb) thread select 8
* thread mono#8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
    frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
libsystem_kernel.dylib`mach_msg_trap:
->  0x65f7e396 <+10>: retl
    0x65f7e397 <+11>: nop

libsystem_kernel.dylib`mach_msg_overwrite_trap:
    0x65f7e398 <+0>:  movl   $0xffffffe0, %eax         ; imm = 0xFFFFFFE0
    0x65f7e39d <+5>:  calll  0x65f85f44                ; _sysenter_trap
(lldb) bt
* thread mono#8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
  * frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
    frame mono#1: 0x65f7e8ff libsystem_kernel.dylib`mach_msg + 47
    frame mono#2: 0x66079679 libxpc.dylib`_xpc_send_serializer + 104
    frame mono#3: 0x660794da libxpc.dylib`_xpc_pipe_simpleroutine + 80
    frame mono#4: 0x66079852 libxpc.dylib`xpc_pipe_simpleroutine + 43
    frame mono#5: 0x66043a8f libsystem_trace.dylib`___os_activity_stream_reflect_block_invoke_2 + 30
    frame mono#6: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono#7: 0x65de3d71 libdispatch.dylib`_dispatch_block_invoke_direct + 257
    frame mono#8: 0x65de3c62 libdispatch.dylib`dispatch_block_perform + 112
    frame mono#9: 0x6604349a libsystem_trace.dylib`_os_activity_stream_reflect + 725
    frame mono#10: 0x6604ef19 libsystem_trace.dylib`_os_log_impl_stream + 468
    frame mono#11: 0x6604e44d libsystem_trace.dylib`_os_log_impl_flatten_and_send + 6410
    frame mono#12: 0x6604cb3b libsystem_trace.dylib`_os_log + 137
    frame mono#13: 0x6604f4aa libsystem_trace.dylib`_os_log_impl + 31
    frame mono#14: 0x4b4eb4e9 WatchConnectivity`WCSerializePayloadDictionary + 393
    frame mono#15: 0x4b4d7c4d WatchConnectivity`-[WCSession onqueue_sendResponseDictionary:identifier:] + 195
    frame mono#16: 0x4b4da435 WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke.411 + 35
    frame mono#17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame mono#18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame mono#19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame mono#20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame mono#21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame mono#22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame mono#23: 0x453cb067 Foundation`____addOperations_block_invoke_2 + 20
    frame mono#24: 0x65dedf49 libdispatch.dylib`_dispatch_block_async_invoke2 + 77
    frame mono#25: 0x65de4461 libdispatch.dylib`_dispatch_block_async_invoke_and_release + 17
    frame mono#26: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono#27: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame mono#28: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame mono#29: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame mono#30: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame mono#31: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame mono#32: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```
which is a thread in a "light" detach state (aka. coop detach), where we only unset the domain:
https://github.com/mono/mono/blob/4cefdcb7ce2d939ee78fb45d1b4913eb3bc064fd/mono/metadata/threads.c#L6084-L6111

Fixes mono#17926
monojenkins added a commit that referenced this pull request Dec 10, 2019
[2019-12] [debugger] skip suspend for unattached threads

When the debugger tries to suspend all the VM threads, it can happen with cooperative-suspend that it tries to suspend a thread that has previously been attached, but then did a "light" detach (that only unsets the domain). With the domain set to `NULL`, looking up a JitInfo for a given `ip` will result into a crash, but it isn't even necessarily needed for the purpose of suspending a thread.

More details: Consider the following:
```
(lldb) c
error: Process is running.  Use 'process interrupt' to pause execution.
Process 12832 stopped
* thread #9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
    frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
   2713         MonoDomain *domain = (MonoDomain *) mono_thread_info_get_suspend_state (info)->unwind_data [MONO_UNWIND_DATA_DOMAIN];
   2714         if (!domain) {
   2715                 /* not attached */
-> 2716                 ji = NULL;
   2717         } else {
   2718                 ji = mono_jit_info_table_find_internal ( domain, MONO_CONTEXT_GET_IP (&mono_thread_info_get_suspend_state (info)->ctx), TRUE, TRUE);
   2719         }
Target 0: (WatchWCSessionAppWatchOSExtension) stopped.
(lldb) bt
* thread #9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  * frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
    frame #1: 0x004e177b WatchWCSessionAppWatchOSExtension`mono_thread_info_safe_suspend_and_run(id=0xb0767000, interrupt_kernel=0, callback=(WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical at debugger-agent.c:2708), user_data=0xb04dc718) at mono-threads.c:1358:19
    frame #2: 0x00222799 WatchWCSessionAppWatchOSExtension`notify_thread(key=0x03994508, value=0x81378c00, user_data=0x00000000) at debugger-agent.c:2747:2
    frame #3: 0x00355bd8 WatchWCSessionAppWatchOSExtension`mono_g_hash_table_foreach(hash=0x8007b4e0, func=(WatchWCSessionAppWatchOSExtension`notify_thread at debugger-agent.c:2733), user_data=0x00000000) at mono-hash.c:310:4
    frame #4: 0x0021e955 WatchWCSessionAppWatchOSExtension`suspend_vm at debugger-agent.c:2844:3
    frame #5: 0x00225ff0 WatchWCSessionAppWatchOSExtension`process_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0, il_offset=0, ctx=0x00000000, events=0x805b28e0, suspend_policy=2) at debugger-agent.c:4012:3
    frame #6: 0x00227c7c WatchWCSessionAppWatchOSExtension`process_profiler_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0) at debugger-agent.c:4072:2
    frame #7: 0x0021b174 WatchWCSessionAppWatchOSExtension`thread_startup(prof=0x00000000, tid=2957889536) at debugger-agent.c:4149:2
    frame #8: 0x0037912d WatchWCSessionAppWatchOSExtension`mono_profiler_raise_thread_started(tid=2957889536) at profiler-events.h:103:1
    frame #9: 0x003d53da WatchWCSessionAppWatchOSExtension`fire_attach_profiler_events(tid=0xb04dd000) at threads.c:1120:2
    frame #10: 0x003d4d83 WatchWCSessionAppWatchOSExtension`mono_thread_attach(domain=0x801750a0) at threads.c:1547:2
    frame #11: 0x003df1a1 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop_internal(domain=0x801750a0, cookie=0xb04dcc0c, stackdata=0xb04dcba8) at threads.c:6008:3
    frame #12: 0x003df287 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop(domain=0x00000000, dummy=0xb04dcc0c) at threads.c:6045:9
    frame #13: 0x005034b8 WatchWCSessionAppWatchOSExtension`::xamarin_switch_gchandle(self=0x80762c20, to_weak=false) at runtime.m:1805:2
    frame #14: 0x005065c1 WatchWCSessionAppWatchOSExtension`::xamarin_retain_trampoline(self=0x80762c20, sel="retain") at trampolines.m:693:2
    frame #15: 0x657ea520 libobjc.A.dylib`objc_retain + 64
    frame #16: 0x4b4d9caa WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke + 279
    frame #17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame #18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame #19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame #20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame #21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame #22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame #23: 0x453cb26e Foundation`____addOperations_block_invoke_4 + 20
    frame #24: 0x65de007b libdispatch.dylib`_dispatch_call_block_and_release + 15
    frame #25: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame #26: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame #27: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame #28: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame #29: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame #30: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame #31: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```

Going further, `info` is about this thread:
```
(lldb) p/x *(int *)(((char *) info->node.key) + 0xa0)
(int) $2 = 0x01243f93
(lldb) thread list
Process 12832 stopped
  thread #1: tid = 0x1243ee1, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_303', queue = 'com.apple.main-thread'
  thread #2: tid = 0x1243ee6, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10
  thread #3: tid = 0x1243ee7, 0x65f81aea libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
  thread #4: tid = 0x1243ee9, 0x65f7e3d2 libsystem_kernel.dylib`semaphore_wait_trap + 10, name = 'Finalizer'
  thread #5: tid = 0x1243eea, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10, name = 'Debugger agent'
  thread #6: tid = 0x1243f1d, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'com.apple.uikit.eventfetch-thread'
  thread #8: tid = 0x1243f93, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
* thread #9: tid = 0x12443a9, 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  thread #10: tid = 0x1244581, 0x65f7fd32 libsystem_kernel.dylib`__workq_kernreturn + 10
(lldb) thread select 8
* thread #8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
    frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
libsystem_kernel.dylib`mach_msg_trap:
->  0x65f7e396 <+10>: retl
    0x65f7e397 <+11>: nop

libsystem_kernel.dylib`mach_msg_overwrite_trap:
    0x65f7e398 <+0>:  movl   $0xffffffe0, %eax         ; imm = 0xFFFFFFE0
    0x65f7e39d <+5>:  calll  0x65f85f44                ; _sysenter_trap
(lldb) bt
* thread #8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
  * frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
    frame #1: 0x65f7e8ff libsystem_kernel.dylib`mach_msg + 47
    frame #2: 0x66079679 libxpc.dylib`_xpc_send_serializer + 104
    frame #3: 0x660794da libxpc.dylib`_xpc_pipe_simpleroutine + 80
    frame #4: 0x66079852 libxpc.dylib`xpc_pipe_simpleroutine + 43
    frame #5: 0x66043a8f libsystem_trace.dylib`___os_activity_stream_reflect_block_invoke_2 + 30
    frame #6: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame #7: 0x65de3d71 libdispatch.dylib`_dispatch_block_invoke_direct + 257
    frame #8: 0x65de3c62 libdispatch.dylib`dispatch_block_perform + 112
    frame #9: 0x6604349a libsystem_trace.dylib`_os_activity_stream_reflect + 725
    frame #10: 0x6604ef19 libsystem_trace.dylib`_os_log_impl_stream + 468
    frame #11: 0x6604e44d libsystem_trace.dylib`_os_log_impl_flatten_and_send + 6410
    frame #12: 0x6604cb3b libsystem_trace.dylib`_os_log + 137
    frame #13: 0x6604f4aa libsystem_trace.dylib`_os_log_impl + 31
    frame #14: 0x4b4eb4e9 WatchConnectivity`WCSerializePayloadDictionary + 393
    frame #15: 0x4b4d7c4d WatchConnectivity`-[WCSession onqueue_sendResponseDictionary:identifier:] + 195
    frame #16: 0x4b4da435 WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke.411 + 35
    frame #17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame #18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame #19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame #20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame #21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame #22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame #23: 0x453cb067 Foundation`____addOperations_block_invoke_2 + 20
    frame #24: 0x65dedf49 libdispatch.dylib`_dispatch_block_async_invoke2 + 77
    frame #25: 0x65de4461 libdispatch.dylib`_dispatch_block_async_invoke_and_release + 17
    frame #26: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame #27: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame #28: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame #29: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame #30: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame #31: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame #32: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```
which is a thread in a "light" detach state (aka. coop detach), where we only unset the domain:
https://github.com/mono/mono/blob/4cefdcb7ce2d939ee78fb45d1b4913eb3bc064fd/mono/metadata/threads.c#L6084-L6111

Fixes #17926



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Backport of #18105.

/cc @lewurm
lambdageek pushed a commit that referenced this pull request Dec 10, 2019
When the debugger tries to suspend all the VM threads, it can happen with cooperative-suspend that it tries to suspend a thread that has previously been attached, but then did a "light" detach (that only unsets the domain). With the domain set to `NULL`, looking up a JitInfo for a given `ip` will result into a crash, but it isn't even necessarily needed for the purpose of suspending a thread.

More details: Consider the following:
```
(lldb) c
error: Process is running.  Use 'process interrupt' to pause execution.
Process 12832 stopped
* thread #9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
    frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
   2713         MonoDomain *domain = (MonoDomain *) mono_thread_info_get_suspend_state (info)->unwind_data [MONO_UNWIND_DATA_DOMAIN];
   2714         if (!domain) {
   2715                 /* not attached */
-> 2716                 ji = NULL;
   2717         } else {
   2718                 ji = mono_jit_info_table_find_internal ( domain, MONO_CONTEXT_GET_IP (&mono_thread_info_get_suspend_state (info)->ctx), TRUE, TRUE);
   2719         }
Target 0: (WatchWCSessionAppWatchOSExtension) stopped.
(lldb) bt
* thread #9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  * frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
    frame #1: 0x004e177b WatchWCSessionAppWatchOSExtension`mono_thread_info_safe_suspend_and_run(id=0xb0767000, interrupt_kernel=0, callback=(WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical at debugger-agent.c:2708), user_data=0xb04dc718) at mono-threads.c:1358:19
    frame #2: 0x00222799 WatchWCSessionAppWatchOSExtension`notify_thread(key=0x03994508, value=0x81378c00, user_data=0x00000000) at debugger-agent.c:2747:2
    frame #3: 0x00355bd8 WatchWCSessionAppWatchOSExtension`mono_g_hash_table_foreach(hash=0x8007b4e0, func=(WatchWCSessionAppWatchOSExtension`notify_thread at debugger-agent.c:2733), user_data=0x00000000) at mono-hash.c:310:4
    frame #4: 0x0021e955 WatchWCSessionAppWatchOSExtension`suspend_vm at debugger-agent.c:2844:3
    frame #5: 0x00225ff0 WatchWCSessionAppWatchOSExtension`process_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0, il_offset=0, ctx=0x00000000, events=0x805b28e0, suspend_policy=2) at debugger-agent.c:4012:3
    frame #6: 0x00227c7c WatchWCSessionAppWatchOSExtension`process_profiler_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0) at debugger-agent.c:4072:2
    frame #7: 0x0021b174 WatchWCSessionAppWatchOSExtension`thread_startup(prof=0x00000000, tid=2957889536) at debugger-agent.c:4149:2
    frame #8: 0x0037912d WatchWCSessionAppWatchOSExtension`mono_profiler_raise_thread_started(tid=2957889536) at profiler-events.h:103:1
    frame #9: 0x003d53da WatchWCSessionAppWatchOSExtension`fire_attach_profiler_events(tid=0xb04dd000) at threads.c:1120:2
    frame #10: 0x003d4d83 WatchWCSessionAppWatchOSExtension`mono_thread_attach(domain=0x801750a0) at threads.c:1547:2
    frame #11: 0x003df1a1 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop_internal(domain=0x801750a0, cookie=0xb04dcc0c, stackdata=0xb04dcba8) at threads.c:6008:3
    frame #12: 0x003df287 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop(domain=0x00000000, dummy=0xb04dcc0c) at threads.c:6045:9
    frame #13: 0x005034b8 WatchWCSessionAppWatchOSExtension`::xamarin_switch_gchandle(self=0x80762c20, to_weak=false) at runtime.m:1805:2
    frame #14: 0x005065c1 WatchWCSessionAppWatchOSExtension`::xamarin_retain_trampoline(self=0x80762c20, sel="retain") at trampolines.m:693:2
    frame #15: 0x657ea520 libobjc.A.dylib`objc_retain + 64
    frame #16: 0x4b4d9caa WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke + 279
    frame #17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame #18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame #19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame #20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame #21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame #22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame #23: 0x453cb26e Foundation`____addOperations_block_invoke_4 + 20
    frame #24: 0x65de007b libdispatch.dylib`_dispatch_call_block_and_release + 15
    frame #25: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame #26: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame #27: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame #28: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame #29: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame #30: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame #31: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```

Going further, `info` is about this thread:
```
(lldb) p/x *(int *)(((char *) info->node.key) + 0xa0)
(int) $2 = 0x01243f93
(lldb) thread list
Process 12832 stopped
  thread #1: tid = 0x1243ee1, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_303', queue = 'com.apple.main-thread'
  thread #2: tid = 0x1243ee6, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10
  thread #3: tid = 0x1243ee7, 0x65f81aea libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
  thread #4: tid = 0x1243ee9, 0x65f7e3d2 libsystem_kernel.dylib`semaphore_wait_trap + 10, name = 'Finalizer'
  thread #5: tid = 0x1243eea, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10, name = 'Debugger agent'
  thread #6: tid = 0x1243f1d, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'com.apple.uikit.eventfetch-thread'
  thread #8: tid = 0x1243f93, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
* thread #9: tid = 0x12443a9, 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  thread #10: tid = 0x1244581, 0x65f7fd32 libsystem_kernel.dylib`__workq_kernreturn + 10
(lldb) thread select 8
* thread #8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
    frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
libsystem_kernel.dylib`mach_msg_trap:
->  0x65f7e396 <+10>: retl
    0x65f7e397 <+11>: nop

libsystem_kernel.dylib`mach_msg_overwrite_trap:
    0x65f7e398 <+0>:  movl   $0xffffffe0, %eax         ; imm = 0xFFFFFFE0
    0x65f7e39d <+5>:  calll  0x65f85f44                ; _sysenter_trap
(lldb) bt
* thread #8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
  * frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
    frame #1: 0x65f7e8ff libsystem_kernel.dylib`mach_msg + 47
    frame #2: 0x66079679 libxpc.dylib`_xpc_send_serializer + 104
    frame #3: 0x660794da libxpc.dylib`_xpc_pipe_simpleroutine + 80
    frame #4: 0x66079852 libxpc.dylib`xpc_pipe_simpleroutine + 43
    frame #5: 0x66043a8f libsystem_trace.dylib`___os_activity_stream_reflect_block_invoke_2 + 30
    frame #6: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame #7: 0x65de3d71 libdispatch.dylib`_dispatch_block_invoke_direct + 257
    frame #8: 0x65de3c62 libdispatch.dylib`dispatch_block_perform + 112
    frame #9: 0x6604349a libsystem_trace.dylib`_os_activity_stream_reflect + 725
    frame #10: 0x6604ef19 libsystem_trace.dylib`_os_log_impl_stream + 468
    frame #11: 0x6604e44d libsystem_trace.dylib`_os_log_impl_flatten_and_send + 6410
    frame #12: 0x6604cb3b libsystem_trace.dylib`_os_log + 137
    frame #13: 0x6604f4aa libsystem_trace.dylib`_os_log_impl + 31
    frame #14: 0x4b4eb4e9 WatchConnectivity`WCSerializePayloadDictionary + 393
    frame #15: 0x4b4d7c4d WatchConnectivity`-[WCSession onqueue_sendResponseDictionary:identifier:] + 195
    frame #16: 0x4b4da435 WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke.411 + 35
    frame #17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame #18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame #19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame #20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame #21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame #22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame #23: 0x453cb067 Foundation`____addOperations_block_invoke_2 + 20
    frame #24: 0x65dedf49 libdispatch.dylib`_dispatch_block_async_invoke2 + 77
    frame #25: 0x65de4461 libdispatch.dylib`_dispatch_block_async_invoke_and_release + 17
    frame #26: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame #27: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame #28: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame #29: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame #30: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame #31: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame #32: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```
which is a thread in a "light" detach state (aka. coop detach), where we only unset the domain:
https://github.com/mono/mono/blob/4cefdcb7ce2d939ee78fb45d1b4913eb3bc064fd/mono/metadata/threads.c#L6084-L6111

Fixes #17926
monojenkins pushed a commit to monojenkins/mono that referenced this pull request Dec 11, 2019
When the debugger tries to suspend all the VM threads, it can happen with cooperative-suspend that it tries to suspend a thread that has previously been attached, but then did a "light" detach (that only unsets the domain). With the domain set to `NULL`, looking up a JitInfo for a given `ip` will result into a crash, but it isn't even necessarily needed for the purpose of suspending a thread.

More details: Consider the following:
```
(lldb) c
error: Process is running.  Use 'process interrupt' to pause execution.
Process 12832 stopped
* thread mono#9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
    frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
   2713         MonoDomain *domain = (MonoDomain *) mono_thread_info_get_suspend_state (info)->unwind_data [MONO_UNWIND_DATA_DOMAIN];
   2714         if (!domain) {
   2715                 /* not attached */
-> 2716                 ji = NULL;
   2717         } else {
   2718                 ji = mono_jit_info_table_find_internal ( domain, MONO_CONTEXT_GET_IP (&mono_thread_info_get_suspend_state (info)->ctx), TRUE, TRUE);
   2719         }
Target 0: (WatchWCSessionAppWatchOSExtension) stopped.
(lldb) bt
* thread mono#9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  * frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
    frame mono#1: 0x004e177b WatchWCSessionAppWatchOSExtension`mono_thread_info_safe_suspend_and_run(id=0xb0767000, interrupt_kernel=0, callback=(WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical at debugger-agent.c:2708), user_data=0xb04dc718) at mono-threads.c:1358:19
    frame mono#2: 0x00222799 WatchWCSessionAppWatchOSExtension`notify_thread(key=0x03994508, value=0x81378c00, user_data=0x00000000) at debugger-agent.c:2747:2
    frame mono#3: 0x00355bd8 WatchWCSessionAppWatchOSExtension`mono_g_hash_table_foreach(hash=0x8007b4e0, func=(WatchWCSessionAppWatchOSExtension`notify_thread at debugger-agent.c:2733), user_data=0x00000000) at mono-hash.c:310:4
    frame mono#4: 0x0021e955 WatchWCSessionAppWatchOSExtension`suspend_vm at debugger-agent.c:2844:3
    frame mono#5: 0x00225ff0 WatchWCSessionAppWatchOSExtension`process_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0, il_offset=0, ctx=0x00000000, events=0x805b28e0, suspend_policy=2) at debugger-agent.c:4012:3
    frame mono#6: 0x00227c7c WatchWCSessionAppWatchOSExtension`process_profiler_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0) at debugger-agent.c:4072:2
    frame mono#7: 0x0021b174 WatchWCSessionAppWatchOSExtension`thread_startup(prof=0x00000000, tid=2957889536) at debugger-agent.c:4149:2
    frame mono#8: 0x0037912d WatchWCSessionAppWatchOSExtension`mono_profiler_raise_thread_started(tid=2957889536) at profiler-events.h:103:1
    frame mono#9: 0x003d53da WatchWCSessionAppWatchOSExtension`fire_attach_profiler_events(tid=0xb04dd000) at threads.c:1120:2
    frame mono#10: 0x003d4d83 WatchWCSessionAppWatchOSExtension`mono_thread_attach(domain=0x801750a0) at threads.c:1547:2
    frame mono#11: 0x003df1a1 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop_internal(domain=0x801750a0, cookie=0xb04dcc0c, stackdata=0xb04dcba8) at threads.c:6008:3
    frame mono#12: 0x003df287 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop(domain=0x00000000, dummy=0xb04dcc0c) at threads.c:6045:9
    frame mono#13: 0x005034b8 WatchWCSessionAppWatchOSExtension`::xamarin_switch_gchandle(self=0x80762c20, to_weak=false) at runtime.m:1805:2
    frame mono#14: 0x005065c1 WatchWCSessionAppWatchOSExtension`::xamarin_retain_trampoline(self=0x80762c20, sel="retain") at trampolines.m:693:2
    frame mono#15: 0x657ea520 libobjc.A.dylib`objc_retain + 64
    frame mono#16: 0x4b4d9caa WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke + 279
    frame mono#17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame mono#18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame mono#19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame mono#20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame mono#21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame mono#22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame mono#23: 0x453cb26e Foundation`____addOperations_block_invoke_4 + 20
    frame mono#24: 0x65de007b libdispatch.dylib`_dispatch_call_block_and_release + 15
    frame mono#25: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono#26: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame mono#27: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame mono#28: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame mono#29: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame mono#30: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame mono#31: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```

Going further, `info` is about this thread:
```
(lldb) p/x *(int *)(((char *) info->node.key) + 0xa0)
(int) $2 = 0x01243f93
(lldb) thread list
Process 12832 stopped
  thread mono#1: tid = 0x1243ee1, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_303', queue = 'com.apple.main-thread'
  thread mono#2: tid = 0x1243ee6, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10
  thread mono#3: tid = 0x1243ee7, 0x65f81aea libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
  thread mono#4: tid = 0x1243ee9, 0x65f7e3d2 libsystem_kernel.dylib`semaphore_wait_trap + 10, name = 'Finalizer'
  thread mono#5: tid = 0x1243eea, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10, name = 'Debugger agent'
  thread mono#6: tid = 0x1243f1d, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'com.apple.uikit.eventfetch-thread'
  thread mono#8: tid = 0x1243f93, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
* thread mono#9: tid = 0x12443a9, 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  thread mono#10: tid = 0x1244581, 0x65f7fd32 libsystem_kernel.dylib`__workq_kernreturn + 10
(lldb) thread select 8
* thread mono#8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
    frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
libsystem_kernel.dylib`mach_msg_trap:
->  0x65f7e396 <+10>: retl
    0x65f7e397 <+11>: nop

libsystem_kernel.dylib`mach_msg_overwrite_trap:
    0x65f7e398 <+0>:  movl   $0xffffffe0, %eax         ; imm = 0xFFFFFFE0
    0x65f7e39d <+5>:  calll  0x65f85f44                ; _sysenter_trap
(lldb) bt
* thread mono#8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
  * frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
    frame mono#1: 0x65f7e8ff libsystem_kernel.dylib`mach_msg + 47
    frame mono#2: 0x66079679 libxpc.dylib`_xpc_send_serializer + 104
    frame mono#3: 0x660794da libxpc.dylib`_xpc_pipe_simpleroutine + 80
    frame mono#4: 0x66079852 libxpc.dylib`xpc_pipe_simpleroutine + 43
    frame mono#5: 0x66043a8f libsystem_trace.dylib`___os_activity_stream_reflect_block_invoke_2 + 30
    frame mono#6: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono#7: 0x65de3d71 libdispatch.dylib`_dispatch_block_invoke_direct + 257
    frame mono#8: 0x65de3c62 libdispatch.dylib`dispatch_block_perform + 112
    frame mono#9: 0x6604349a libsystem_trace.dylib`_os_activity_stream_reflect + 725
    frame mono#10: 0x6604ef19 libsystem_trace.dylib`_os_log_impl_stream + 468
    frame mono#11: 0x6604e44d libsystem_trace.dylib`_os_log_impl_flatten_and_send + 6410
    frame mono#12: 0x6604cb3b libsystem_trace.dylib`_os_log + 137
    frame mono#13: 0x6604f4aa libsystem_trace.dylib`_os_log_impl + 31
    frame mono#14: 0x4b4eb4e9 WatchConnectivity`WCSerializePayloadDictionary + 393
    frame mono#15: 0x4b4d7c4d WatchConnectivity`-[WCSession onqueue_sendResponseDictionary:identifier:] + 195
    frame mono#16: 0x4b4da435 WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke.411 + 35
    frame mono#17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame mono#18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame mono#19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame mono#20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame mono#21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame mono#22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame mono#23: 0x453cb067 Foundation`____addOperations_block_invoke_2 + 20
    frame mono#24: 0x65dedf49 libdispatch.dylib`_dispatch_block_async_invoke2 + 77
    frame mono#25: 0x65de4461 libdispatch.dylib`_dispatch_block_async_invoke_and_release + 17
    frame mono#26: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono#27: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame mono#28: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame mono#29: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame mono#30: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame mono#31: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame mono#32: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```
which is a thread in a "light" detach state (aka. coop detach), where we only unset the domain:
https://github.com/mono/mono/blob/4cefdcb7ce2d939ee78fb45d1b4913eb3bc064fd/mono/metadata/threads.c#L6084-L6111

Fixes mono#17926
monojenkins added a commit that referenced this pull request Dec 12, 2019
[2019-08] [debugger] skip suspend for unattached threads

When the debugger tries to suspend all the VM threads, it can happen with cooperative-suspend that it tries to suspend a thread that has previously been attached, but then did a "light" detach (that only unsets the domain). With the domain set to `NULL`, looking up a JitInfo for a given `ip` will result into a crash, but it isn't even necessarily needed for the purpose of suspending a thread.

More details: Consider the following:
```
(lldb) c
error: Process is running.  Use 'process interrupt' to pause execution.
Process 12832 stopped
* thread #9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
    frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
   2713         MonoDomain *domain = (MonoDomain *) mono_thread_info_get_suspend_state (info)->unwind_data [MONO_UNWIND_DATA_DOMAIN];
   2714         if (!domain) {
   2715                 /* not attached */
-> 2716                 ji = NULL;
   2717         } else {
   2718                 ji = mono_jit_info_table_find_internal ( domain, MONO_CONTEXT_GET_IP (&mono_thread_info_get_suspend_state (info)->ctx), TRUE, TRUE);
   2719         }
Target 0: (WatchWCSessionAppWatchOSExtension) stopped.
(lldb) bt
* thread #9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  * frame #0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
    frame #1: 0x004e177b WatchWCSessionAppWatchOSExtension`mono_thread_info_safe_suspend_and_run(id=0xb0767000, interrupt_kernel=0, callback=(WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical at debugger-agent.c:2708), user_data=0xb04dc718) at mono-threads.c:1358:19
    frame #2: 0x00222799 WatchWCSessionAppWatchOSExtension`notify_thread(key=0x03994508, value=0x81378c00, user_data=0x00000000) at debugger-agent.c:2747:2
    frame #3: 0x00355bd8 WatchWCSessionAppWatchOSExtension`mono_g_hash_table_foreach(hash=0x8007b4e0, func=(WatchWCSessionAppWatchOSExtension`notify_thread at debugger-agent.c:2733), user_data=0x00000000) at mono-hash.c:310:4
    frame #4: 0x0021e955 WatchWCSessionAppWatchOSExtension`suspend_vm at debugger-agent.c:2844:3
    frame #5: 0x00225ff0 WatchWCSessionAppWatchOSExtension`process_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0, il_offset=0, ctx=0x00000000, events=0x805b28e0, suspend_policy=2) at debugger-agent.c:4012:3
    frame #6: 0x00227c7c WatchWCSessionAppWatchOSExtension`process_profiler_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0) at debugger-agent.c:4072:2
    frame #7: 0x0021b174 WatchWCSessionAppWatchOSExtension`thread_startup(prof=0x00000000, tid=2957889536) at debugger-agent.c:4149:2
    frame #8: 0x0037912d WatchWCSessionAppWatchOSExtension`mono_profiler_raise_thread_started(tid=2957889536) at profiler-events.h:103:1
    frame #9: 0x003d53da WatchWCSessionAppWatchOSExtension`fire_attach_profiler_events(tid=0xb04dd000) at threads.c:1120:2
    frame #10: 0x003d4d83 WatchWCSessionAppWatchOSExtension`mono_thread_attach(domain=0x801750a0) at threads.c:1547:2
    frame #11: 0x003df1a1 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop_internal(domain=0x801750a0, cookie=0xb04dcc0c, stackdata=0xb04dcba8) at threads.c:6008:3
    frame #12: 0x003df287 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop(domain=0x00000000, dummy=0xb04dcc0c) at threads.c:6045:9
    frame #13: 0x005034b8 WatchWCSessionAppWatchOSExtension`::xamarin_switch_gchandle(self=0x80762c20, to_weak=false) at runtime.m:1805:2
    frame #14: 0x005065c1 WatchWCSessionAppWatchOSExtension`::xamarin_retain_trampoline(self=0x80762c20, sel="retain") at trampolines.m:693:2
    frame #15: 0x657ea520 libobjc.A.dylib`objc_retain + 64
    frame #16: 0x4b4d9caa WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke + 279
    frame #17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame #18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame #19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame #20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame #21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame #22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame #23: 0x453cb26e Foundation`____addOperations_block_invoke_4 + 20
    frame #24: 0x65de007b libdispatch.dylib`_dispatch_call_block_and_release + 15
    frame #25: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame #26: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame #27: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame #28: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame #29: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame #30: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame #31: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```

Going further, `info` is about this thread:
```
(lldb) p/x *(int *)(((char *) info->node.key) + 0xa0)
(int) $2 = 0x01243f93
(lldb) thread list
Process 12832 stopped
  thread #1: tid = 0x1243ee1, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_303', queue = 'com.apple.main-thread'
  thread #2: tid = 0x1243ee6, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10
  thread #3: tid = 0x1243ee7, 0x65f81aea libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
  thread #4: tid = 0x1243ee9, 0x65f7e3d2 libsystem_kernel.dylib`semaphore_wait_trap + 10, name = 'Finalizer'
  thread #5: tid = 0x1243eea, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10, name = 'Debugger agent'
  thread #6: tid = 0x1243f1d, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'com.apple.uikit.eventfetch-thread'
  thread #8: tid = 0x1243f93, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
* thread #9: tid = 0x12443a9, 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  thread #10: tid = 0x1244581, 0x65f7fd32 libsystem_kernel.dylib`__workq_kernreturn + 10
(lldb) thread select 8
* thread #8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
    frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
libsystem_kernel.dylib`mach_msg_trap:
->  0x65f7e396 <+10>: retl
    0x65f7e397 <+11>: nop

libsystem_kernel.dylib`mach_msg_overwrite_trap:
    0x65f7e398 <+0>:  movl   $0xffffffe0, %eax         ; imm = 0xFFFFFFE0
    0x65f7e39d <+5>:  calll  0x65f85f44                ; _sysenter_trap
(lldb) bt
* thread #8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
  * frame #0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
    frame #1: 0x65f7e8ff libsystem_kernel.dylib`mach_msg + 47
    frame #2: 0x66079679 libxpc.dylib`_xpc_send_serializer + 104
    frame #3: 0x660794da libxpc.dylib`_xpc_pipe_simpleroutine + 80
    frame #4: 0x66079852 libxpc.dylib`xpc_pipe_simpleroutine + 43
    frame #5: 0x66043a8f libsystem_trace.dylib`___os_activity_stream_reflect_block_invoke_2 + 30
    frame #6: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame #7: 0x65de3d71 libdispatch.dylib`_dispatch_block_invoke_direct + 257
    frame #8: 0x65de3c62 libdispatch.dylib`dispatch_block_perform + 112
    frame #9: 0x6604349a libsystem_trace.dylib`_os_activity_stream_reflect + 725
    frame #10: 0x6604ef19 libsystem_trace.dylib`_os_log_impl_stream + 468
    frame #11: 0x6604e44d libsystem_trace.dylib`_os_log_impl_flatten_and_send + 6410
    frame #12: 0x6604cb3b libsystem_trace.dylib`_os_log + 137
    frame #13: 0x6604f4aa libsystem_trace.dylib`_os_log_impl + 31
    frame #14: 0x4b4eb4e9 WatchConnectivity`WCSerializePayloadDictionary + 393
    frame #15: 0x4b4d7c4d WatchConnectivity`-[WCSession onqueue_sendResponseDictionary:identifier:] + 195
    frame #16: 0x4b4da435 WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke.411 + 35
    frame #17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame #18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame #19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame #20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame #21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame #22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame #23: 0x453cb067 Foundation`____addOperations_block_invoke_2 + 20
    frame #24: 0x65dedf49 libdispatch.dylib`_dispatch_block_async_invoke2 + 77
    frame #25: 0x65de4461 libdispatch.dylib`_dispatch_block_async_invoke_and_release + 17
    frame #26: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame #27: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame #28: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame #29: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame #30: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame #31: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame #32: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```
which is a thread in a "light" detach state (aka. coop detach), where we only unset the domain:
https://github.com/mono/mono/blob/4cefdcb7ce2d939ee78fb45d1b4913eb3bc064fd/mono/metadata/threads.c#L6084-L6111

Fixes #17926



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Backport of #18105.

/cc @lewurm
ManickaP pushed a commit to ManickaP/runtime that referenced this pull request Jan 20, 2020
…no#16973)

* [threads] clear small_id_key TLS when unregistering a thread

Fixes
```
* thread mono/mono#12, name = 'tid_a507', stop reason = EXC_BREAKPOINT (code=1, subcode=0x1be66144)
  * frame mono/mono#0: 0x1be66144 libsystem_c.dylib`__abort + 184
    frame mono/mono#1: 0x1be6608c libsystem_c.dylib`abort + 152
    frame mono/mono#2: 0x003e1fa0 monotouchtest`log_callback(log_domain=0x00000000, log_level="error", message="* Assertion at ../../../../../mono/utils/hazard-pointer.c:158, condition `mono_bitset_test_fast (small_id_table, id)' not met\n", fatal=4, user_data=0x00000000) at runtime.m:1251:3
    frame mono/mono#3: 0x003abf44 monotouchtest`monoeg_g_logv_nofree(log_domain=0x00000000, log_level=G_LOG_LEVEL_ERROR, format=<unavailable>, args=<unavailable>) at goutput.c:149:2 [opt]
    frame mono/mono#4: 0x003abfb4 monotouchtest`monoeg_assertion_message(format=<unavailable>) at goutput.c:184:22 [opt]
    frame mono/mono#5: 0x003904dc monotouchtest`mono_thread_small_id_free(id=<unavailable>) at hazard-pointer.c:0:2 [opt]
    frame mono/mono#6: 0x003a0a74 monotouchtest`unregister_thread(arg=0x15c88400) at mono-threads.c:588:2 [opt]
    frame mono/mono#7: 0x00336110 monotouchtest`mono_thread_detach_if_exiting at threads.c:1571:4 [opt]
    frame mono/mono#8: 0x003e7a14 monotouchtest`::xamarin_release_trampoline(self=0x166452f0, sel="release") at trampolines.m:644:3
    frame mono/mono#9: 0x001cdc40 monotouchtest`::-[__Xamarin_NSTimerActionDispatcher release](self=0x166452f0, _cmd="release") at registrar.m:83445:3
    frame mono/mono#10: 0x1ce2ae68 Foundation`_timerRelease + 80
    frame mono/mono#11: 0x1c31b56c CoreFoundation`CFRunLoopTimerInvalidate + 612
    frame mono/mono#12: 0x1c31a554 CoreFoundation`__CFRunLoopTimerDeallocate + 32
    frame mono/mono#13: 0x1c31dde4 CoreFoundation`_CFRelease + 220
    frame mono/mono#14: 0x1c2be6e8 CoreFoundation`__CFArrayReleaseValues + 500
    frame mono/mono#15: 0x1c2be4c4 CoreFoundation`CFArrayRemoveAllValues + 104
    frame mono/mono#16: 0x1c31ff64 CoreFoundation`__CFSetApplyFunction_block_invoke + 24
    frame mono/mono#17: 0x1c3b2e18 CoreFoundation`CFBasicHashApply + 116
    frame mono/mono#18: 0x1c31ff10 CoreFoundation`CFSetApplyFunction + 160
    frame mono/mono#19: 0x1c3152cc CoreFoundation`__CFRunLoopDeallocate + 204
    frame mono/mono#20: 0x1c31dde4 CoreFoundation`_CFRelease + 220
    frame mono/mono#21: 0x1c304a80 CoreFoundation`__CFTSDFinalize + 144
    frame mono/mono#22: 0x1bfa324c libsystem_pthread.dylib`_pthread_tsd_cleanup + 644
    frame mono/mono#23: 0x1bf9cc08 libsystem_pthread.dylib`_pthread_exit + 80
    frame mono/mono#24: 0x1bf9af24 libsystem_pthread.dylib`pthread_exit + 36
    frame mono/mono#25: 0x0039df84 monotouchtest`mono_threads_platform_exit(exit_code=<unavailable>) at mono-threads-posix.c:145:2 [opt]
    frame mono/mono#26: 0x0033bb84 monotouchtest`start_wrapper(data=0x1609e1c0) at threads.c:1296:2 [opt]
    frame mono/mono#27: 0x1bf9b914 libsystem_pthread.dylib`_pthread_body + 128
    frame mono/mono#28: 0x1bf9b874 libsystem_pthread.dylib`_pthread_start + 44
    frame mono/mono#29: 0x1bfa3b94 libsystem_pthread.dylib`thread_start + 4
```

* Update mono/utils/mono-threads.c

Co-Authored-By: Aleksey Kliger (λgeek) <akliger@gmail.com>


Commit migrated from mono/mono@749493d
ManickaP pushed a commit to ManickaP/runtime that referenced this pull request Jan 20, 2020
When the debugger tries to suspend all the VM threads, it can happen with cooperative-suspend that it tries to suspend a thread that has previously been attached, but then did a "light" detach (that only unsets the domain). With the domain set to `NULL`, looking up a JitInfo for a given `ip` will result into a crash, but it isn't even necessarily needed for the purpose of suspending a thread.

More details: Consider the following:
```
(lldb) c
error: Process is running.  Use 'process interrupt' to pause execution.
Process 12832 stopped
* thread mono/mono#9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
    frame mono/mono#0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
   2713         MonoDomain *domain = (MonoDomain *) mono_thread_info_get_suspend_state (info)->unwind_data [MONO_UNWIND_DATA_DOMAIN];
   2714         if (!domain) {
   2715                 /* not attached */
-> 2716                 ji = NULL;
   2717         } else {
   2718                 ji = mono_jit_info_table_find_internal ( domain, MONO_CONTEXT_GET_IP (&mono_thread_info_get_suspend_state (info)->ctx), TRUE, TRUE);
   2719         }
Target 0: (WatchWCSessionAppWatchOSExtension) stopped.
(lldb) bt
* thread mono/mono#9, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  * frame mono/mono#0: 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6
    frame mono/mono#1: 0x004e177b WatchWCSessionAppWatchOSExtension`mono_thread_info_safe_suspend_and_run(id=0xb0767000, interrupt_kernel=0, callback=(WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical at debugger-agent.c:2708), user_data=0xb04dc718) at mono-threads.c:1358:19
    frame mono/mono#2: 0x00222799 WatchWCSessionAppWatchOSExtension`notify_thread(key=0x03994508, value=0x81378c00, user_data=0x00000000) at debugger-agent.c:2747:2
    frame mono/mono#3: 0x00355bd8 WatchWCSessionAppWatchOSExtension`mono_g_hash_table_foreach(hash=0x8007b4e0, func=(WatchWCSessionAppWatchOSExtension`notify_thread at debugger-agent.c:2733), user_data=0x00000000) at mono-hash.c:310:4
    frame mono/mono#4: 0x0021e955 WatchWCSessionAppWatchOSExtension`suspend_vm at debugger-agent.c:2844:3
    frame mono/mono#5: 0x00225ff0 WatchWCSessionAppWatchOSExtension`process_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0, il_offset=0, ctx=0x00000000, events=0x805b28e0, suspend_policy=2) at debugger-agent.c:4012:3
    frame mono/mono#6: 0x00227c7c WatchWCSessionAppWatchOSExtension`process_profiler_event(event=EVENT_KIND_THREAD_START, arg=0x039945d0) at debugger-agent.c:4072:2
    frame mono/mono#7: 0x0021b174 WatchWCSessionAppWatchOSExtension`thread_startup(prof=0x00000000, tid=2957889536) at debugger-agent.c:4149:2
    frame mono/mono#8: 0x0037912d WatchWCSessionAppWatchOSExtension`mono_profiler_raise_thread_started(tid=2957889536) at profiler-events.h:103:1
    frame mono/mono#9: 0x003d53da WatchWCSessionAppWatchOSExtension`fire_attach_profiler_events(tid=0xb04dd000) at threads.c:1120:2
    frame mono/mono#10: 0x003d4d83 WatchWCSessionAppWatchOSExtension`mono_thread_attach(domain=0x801750a0) at threads.c:1547:2
    frame mono/mono#11: 0x003df1a1 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop_internal(domain=0x801750a0, cookie=0xb04dcc0c, stackdata=0xb04dcba8) at threads.c:6008:3
    frame mono/mono#12: 0x003df287 WatchWCSessionAppWatchOSExtension`mono_threads_attach_coop(domain=0x00000000, dummy=0xb04dcc0c) at threads.c:6045:9
    frame mono/mono#13: 0x005034b8 WatchWCSessionAppWatchOSExtension`::xamarin_switch_gchandle(self=0x80762c20, to_weak=false) at runtime.m:1805:2
    frame mono/mono#14: 0x005065c1 WatchWCSessionAppWatchOSExtension`::xamarin_retain_trampoline(self=0x80762c20, sel="retain") at trampolines.m:693:2
    frame mono/mono#15: 0x657ea520 libobjc.A.dylib`objc_retain + 64
    frame mono/mono#16: 0x4b4d9caa WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke + 279
    frame mono/mono#17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame mono/mono#18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame mono/mono#19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame mono/mono#20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame mono/mono#21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame mono/mono#22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame mono/mono#23: 0x453cb26e Foundation`____addOperations_block_invoke_4 + 20
    frame mono/mono#24: 0x65de007b libdispatch.dylib`_dispatch_call_block_and_release + 15
    frame mono/mono#25: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono/mono#26: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame mono/mono#27: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame mono/mono#28: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame mono/mono#29: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame mono/mono#30: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame mono/mono#31: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```

Going further, `info` is about this thread:
```
(lldb) p/x *(int *)(((char *) info->node.key) + 0xa0)
(int) $2 = 0x01243f93
(lldb) thread list
Process 12832 stopped
  thread mono/mono#1: tid = 0x1243ee1, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_303', queue = 'com.apple.main-thread'
  thread mono/mono#2: tid = 0x1243ee6, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10
  thread mono/mono#3: tid = 0x1243ee7, 0x65f81aea libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
  thread mono/mono#4: tid = 0x1243ee9, 0x65f7e3d2 libsystem_kernel.dylib`semaphore_wait_trap + 10, name = 'Finalizer'
  thread mono/mono#5: tid = 0x1243eea, 0x65f816e2 libsystem_kernel.dylib`__recvfrom + 10, name = 'Debugger agent'
  thread mono/mono#6: tid = 0x1243f1d, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'com.apple.uikit.eventfetch-thread'
  thread mono/mono#8: tid = 0x1243f93, 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
* thread mono/mono#9: tid = 0x12443a9, 0x00222870 WatchWCSessionAppWatchOSExtension`debugger_interrupt_critical(info=0x81365400, user_data=0xb04dc718) at debugger-agent.c:2716:6, name = 'tid_a31f', queue = 'NSOperationQueue 0x8069b670 (QOS: UTILITY)', stop reason = breakpoint 1.1
  thread mono/mono#10: tid = 0x1244581, 0x65f7fd32 libsystem_kernel.dylib`__workq_kernreturn + 10
(lldb) thread select 8
* thread mono/mono#8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
    frame mono/mono#0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
libsystem_kernel.dylib`mach_msg_trap:
->  0x65f7e396 <+10>: retl
    0x65f7e397 <+11>: nop

libsystem_kernel.dylib`mach_msg_overwrite_trap:
    0x65f7e398 <+0>:  movl   $0xffffffe0, %eax         ; imm = 0xFFFFFFE0
    0x65f7e39d <+5>:  calll  0x65f85f44                ; _sysenter_trap
(lldb) bt
* thread mono/mono#8, name = 'tid_6d0f', queue = 'NSOperationQueue 0x8069b300 (QOS: UTILITY)'
  * frame mono/mono#0: 0x65f7e396 libsystem_kernel.dylib`mach_msg_trap + 10
    frame mono/mono#1: 0x65f7e8ff libsystem_kernel.dylib`mach_msg + 47
    frame mono/mono#2: 0x66079679 libxpc.dylib`_xpc_send_serializer + 104
    frame mono/mono#3: 0x660794da libxpc.dylib`_xpc_pipe_simpleroutine + 80
    frame mono/mono#4: 0x66079852 libxpc.dylib`xpc_pipe_simpleroutine + 43
    frame mono/mono#5: 0x66043a8f libsystem_trace.dylib`___os_activity_stream_reflect_block_invoke_2 + 30
    frame mono/mono#6: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono/mono#7: 0x65de3d71 libdispatch.dylib`_dispatch_block_invoke_direct + 257
    frame mono/mono#8: 0x65de3c62 libdispatch.dylib`dispatch_block_perform + 112
    frame mono/mono#9: 0x6604349a libsystem_trace.dylib`_os_activity_stream_reflect + 725
    frame mono/mono#10: 0x6604ef19 libsystem_trace.dylib`_os_log_impl_stream + 468
    frame mono/mono#11: 0x6604e44d libsystem_trace.dylib`_os_log_impl_flatten_and_send + 6410
    frame mono/mono#12: 0x6604cb3b libsystem_trace.dylib`_os_log + 137
    frame mono/mono#13: 0x6604f4aa libsystem_trace.dylib`_os_log_impl + 31
    frame mono/mono#14: 0x4b4eb4e9 WatchConnectivity`WCSerializePayloadDictionary + 393
    frame mono/mono#15: 0x4b4d7c4d WatchConnectivity`-[WCSession onqueue_sendResponseDictionary:identifier:] + 195
    frame mono/mono#16: 0x4b4da435 WatchConnectivity`__66-[WCSession onqueue_handleDictionaryMessageRequest:withPairingID:]_block_invoke.411 + 35
    frame mono/mono#17: 0x453c7df7 Foundation`__NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    frame mono/mono#18: 0x453c7cf4 Foundation`-[NSBlockOperation main] + 88
    frame mono/mono#19: 0x453cacee Foundation`__NSOPERATION_IS_INVOKING_MAIN__ + 27
    frame mono/mono#20: 0x453c6ebd Foundation`-[NSOperation start] + 835
    frame mono/mono#21: 0x453cb606 Foundation`__NSOPERATIONQUEUE_IS_STARTING_AN_OPERATION__ + 27
    frame mono/mono#22: 0x453cb12e Foundation`__NSOQSchedule_f + 194
    frame mono/mono#23: 0x453cb067 Foundation`____addOperations_block_invoke_2 + 20
    frame mono/mono#24: 0x65dedf49 libdispatch.dylib`_dispatch_block_async_invoke2 + 77
    frame mono/mono#25: 0x65de4461 libdispatch.dylib`_dispatch_block_async_invoke_and_release + 17
    frame mono/mono#26: 0x65de126f libdispatch.dylib`_dispatch_client_callout + 14
    frame mono/mono#27: 0x65de3788 libdispatch.dylib`_dispatch_continuation_pop + 421
    frame mono/mono#28: 0x65de2ee3 libdispatch.dylib`_dispatch_async_redirect_invoke + 818
    frame mono/mono#29: 0x65df087d libdispatch.dylib`_dispatch_root_queue_drain + 354
    frame mono/mono#30: 0x65df0ff3 libdispatch.dylib`_dispatch_worker_thread2 + 109
    frame mono/mono#31: 0x66024fa0 libsystem_pthread.dylib`_pthread_wqthread + 208
    frame mono/mono#32: 0x66024e44 libsystem_pthread.dylib`start_wqthread + 36
```
which is a thread in a "light" detach state (aka. coop detach), where we only unset the domain:
https://github.com/mono/mono/blob/mono/mono@4cefdcb7ce2d939ee78fb45d1b4913eb3bc064fd/mono/metadata/threads.c#L6084-L6111

Fixes mono/mono#17926

Commit migrated from mono/mono@80b1e10
lewurm added a commit to lewurm/mono that referenced this pull request Jan 21, 2020
`jit_tls->interp_context` gets initialized lazily, that is, upon the first interpreter execution on a specific thread (e.g. via interp_runtime_invoke). However, with mixed mode the execution can purely happen in AOT code upon the first interaction with the managed debugger.

Stack trace:

```
  thread #1, name = 'tid_407', queue = 'com.apple.main-thread'
    frame #0: 0x0000000190aedc94 libsystem_kernel.dylib`__psynch_cvwait + 8
    frame #1: 0x0000000190a0f094 libsystem_pthread.dylib`_pthread_cond_wait$VARIANT$armv81 + 672
    frame #2: 0x000000010431318c reloadcontext.iOS`mono_os_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-os-mutex.h:219:8
    frame mono#3: 0x0000000104312a68 reloadcontext.iOS`mono_coop_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-coop-mutex.h:91:2
    frame mono#4: 0x0000000104312858 reloadcontext.iOS`suspend_current at debugger-agent.c:3021:4
    frame mono#5: 0x000000010431be18 reloadcontext.iOS`process_event(event=EVENT_KIND_BREAKPOINT, arg=0x0000000145d09ae8, il_offset=0, ctx=0x0000000149015c20, events=0x0000000000000000, suspend_policy=2) at debugger-agent.c:4058:3
    frame mono#6: 0x0000000104310cf4 reloadcontext.iOS`process_breakpoint_events(_evts=0x000000028351a680, method=0x0000000145d09ae8, ctx=0x0000000149015c20, il_offset=0) at debugger-agent.c:4722:3
    frame mono#7: 0x000000010432f1c8 reloadcontext.iOS`mono_de_process_breakpoint(void_tls=0x0000000149014e00, from_signal=0) at debugger-engine.c:1141:2
    frame mono#8: 0x000000010430f238 reloadcontext.iOS`debugger_agent_breakpoint_from_context(ctx=0x000000016f656790) at debugger-agent.c:4938:2
    frame mono#9: 0x00000001011b73a4 reloadcontext.iOS`sdb_breakpoint_trampoline + 148
    frame mono#10: 0x00000001008511b4 reloadcontext.iOS`reloadcontext_iOS_Application_Main_string__(args=0x000000010703a030) at Main.cs:14
    frame mono#11: 0x00000001010f9730 reloadcontext.iOS`wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr + 272
    frame mono#12: 0x00000001042fd8b8 reloadcontext.iOS`mono_jit_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at mini-runtime.c:3162:3
    frame mono#13: 0x0000000104411950 reloadcontext.iOS`do_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at object.c:3052:11
    frame mono#14: 0x000000010440c4dc reloadcontext.iOS`mono_runtime_invoke_checked(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, error=0x000000016f656ff8) at object.c:3220:9
    frame mono#15: 0x0000000104415ae0 reloadcontext.iOS`do_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5184:3
    frame mono#16: 0x00000001044144ac reloadcontext.iOS`mono_runtime_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5281:9
    frame mono#17: 0x0000000104414500 reloadcontext.iOS`mono_runtime_run_main_checked(method=0x0000000145d09ae8, argc=1, argv=0x000000016f6570d0, error=0x000000016f656ff8) at object.c:4734:9
    frame mono#18: 0x00000001042d3b54 reloadcontext.iOS`mono_jit_exec_internal(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1320:13
    frame mono#19: 0x00000001042d39a4 reloadcontext.iOS`mono_jit_exec(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1265:7
    frame mono#20: 0x0000000104597994 reloadcontext.iOS`::xamarin_main(argc=5, argv=0x000000016f657a80, launch_mode=XamarinLaunchModeApp) at monotouch-main.m:483:8
    frame mono#21: 0x00000001008510dc reloadcontext.iOS`main(argc=5, argv=0x000000016f657a80) at main.m:104:11
    frame mono#22: 0x0000000190af8360 libdyld.dylib`start + 4
[...]
* thread mono#5, name = 'Debugger agent', stop reason = signal SIGABRT
  * frame #0: 0x0000000190aedec4 libsystem_kernel.dylib`__pthread_kill + 8
    frame #1: 0x0000000190a0d724 libsystem_pthread.dylib`pthread_kill$VARIANT$armv81 + 216
    frame #2: 0x000000019095d844 libsystem_c.dylib`abort + 100
    frame mono#3: 0x00000001045871b4 reloadcontext.iOS`log_callback(log_domain=0x0000000000000000, log_level="error", message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", fatal=4, user_data=0x0000000000000000) at runtime.m:1213:3
    frame mono#4: 0x0000000104544fc8 reloadcontext.iOS`eglib_log_adapter(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", user_data=0x0000000000000000) at mono-logger.c:405:2
    frame mono#5: 0x000000010456093c reloadcontext.iOS`monoeg_g_logstr(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, msg="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n") at goutput.c:134:2
    frame mono#6: 0x0000000104560598 reloadcontext.iOS`monoeg_g_logv_nofree(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, format="* Assertion at %s:%d, condition `%s' not met\n", args="e\x12z\x04\x01") at goutput.c:149:2
    frame mono#7: 0x000000010456061c reloadcontext.iOS`monoeg_assertion_message(format="* Assertion at %s:%d, condition `%s' not met\n") at goutput.c:184:22
    frame mono#8: 0x0000000104560674 reloadcontext.iOS`mono_assertion_message(file="../../../../../mono/mini/interp/interp.c", line=7176, condition="context") at goutput.c:203:2
    frame mono#9: 0x000000010459b570 reloadcontext.iOS`interp_get_resume_state(jit_tls=0x000000014900d000, has_resume_state=0x000000016fc7a9f4, interp_frame=0x000000016fc7a9e8, handler_ip=0x000000016fc7a9e0) at interp.c:7176:2
    frame mono#10: 0x0000000104319420 reloadcontext.iOS`compute_frame_info(thread=0x0000000104fe4130, tls=0x0000000149014e00, force_update=1) at debugger-agent.c:3422:3
    frame mono#11: 0x0000000104320d40 reloadcontext.iOS`thread_commands(command=1, p="", end="", buf=0x000000016fc7acf8) at debugger-agent.c:9048:3
    frame mono#12: 0x000000010431cca0 reloadcontext.iOS`debugger_thread(arg=0x0000000000000000) at debugger-agent.c:10132:10
    frame mono#13: 0x000000010447eb04 reloadcontext.iOS`start_wrapper_internal(start_info=0x0000000000000000, stack_ptr=0x000000016fc7b000) at threads.c:1232:3
    frame mono#14: 0x000000010447e788 reloadcontext.iOS`start_wrapper(data=0x000000028203ef40) at threads.c:1305:8
    frame mono#15: 0x0000000190a11d8c libsystem_pthread.dylib`_pthread_start + 15
[...]
```

Thanks to @drasticactions for helping me to reproduce.

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1050615
lewurm added a commit to lewurm/mono that referenced this pull request Jan 21, 2020
`jit_tls->interp_context` gets initialized lazily, that is, upon the first interpreter execution on a specific thread (e.g. via interp_runtime_invoke). However, with mixed mode the execution can purely happen in AOT code upon the first interaction with the managed debugger.

Stack trace:

```
  thread #1, name = 'tid_407', queue = 'com.apple.main-thread'
    frame #0: 0x0000000190aedc94 libsystem_kernel.dylib`__psynch_cvwait + 8
    frame #1: 0x0000000190a0f094 libsystem_pthread.dylib`_pthread_cond_wait$VARIANT$armv81 + 672
    frame #2: 0x000000010431318c reloadcontext.iOS`mono_os_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-os-mutex.h:219:8
    frame mono#3: 0x0000000104312a68 reloadcontext.iOS`mono_coop_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-coop-mutex.h:91:2
    frame mono#4: 0x0000000104312858 reloadcontext.iOS`suspend_current at debugger-agent.c:3021:4
    frame mono#5: 0x000000010431be18 reloadcontext.iOS`process_event(event=EVENT_KIND_BREAKPOINT, arg=0x0000000145d09ae8, il_offset=0, ctx=0x0000000149015c20, events=0x0000000000000000, suspend_policy=2) at debugger-agent.c:4058:3
    frame mono#6: 0x0000000104310cf4 reloadcontext.iOS`process_breakpoint_events(_evts=0x000000028351a680, method=0x0000000145d09ae8, ctx=0x0000000149015c20, il_offset=0) at debugger-agent.c:4722:3
    frame mono#7: 0x000000010432f1c8 reloadcontext.iOS`mono_de_process_breakpoint(void_tls=0x0000000149014e00, from_signal=0) at debugger-engine.c:1141:2
    frame mono#8: 0x000000010430f238 reloadcontext.iOS`debugger_agent_breakpoint_from_context(ctx=0x000000016f656790) at debugger-agent.c:4938:2
    frame mono#9: 0x00000001011b73a4 reloadcontext.iOS`sdb_breakpoint_trampoline + 148
    frame mono#10: 0x00000001008511b4 reloadcontext.iOS`reloadcontext_iOS_Application_Main_string__(args=0x000000010703a030) at Main.cs:14
    frame mono#11: 0x00000001010f9730 reloadcontext.iOS`wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr + 272
    frame mono#12: 0x00000001042fd8b8 reloadcontext.iOS`mono_jit_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at mini-runtime.c:3162:3
    frame mono#13: 0x0000000104411950 reloadcontext.iOS`do_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at object.c:3052:11
    frame mono#14: 0x000000010440c4dc reloadcontext.iOS`mono_runtime_invoke_checked(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, error=0x000000016f656ff8) at object.c:3220:9
    frame mono#15: 0x0000000104415ae0 reloadcontext.iOS`do_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5184:3
    frame mono#16: 0x00000001044144ac reloadcontext.iOS`mono_runtime_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5281:9
    frame mono#17: 0x0000000104414500 reloadcontext.iOS`mono_runtime_run_main_checked(method=0x0000000145d09ae8, argc=1, argv=0x000000016f6570d0, error=0x000000016f656ff8) at object.c:4734:9
    frame mono#18: 0x00000001042d3b54 reloadcontext.iOS`mono_jit_exec_internal(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1320:13
    frame mono#19: 0x00000001042d39a4 reloadcontext.iOS`mono_jit_exec(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1265:7
    frame mono#20: 0x0000000104597994 reloadcontext.iOS`::xamarin_main(argc=5, argv=0x000000016f657a80, launch_mode=XamarinLaunchModeApp) at monotouch-main.m:483:8
    frame mono#21: 0x00000001008510dc reloadcontext.iOS`main(argc=5, argv=0x000000016f657a80) at main.m:104:11
    frame mono#22: 0x0000000190af8360 libdyld.dylib`start + 4
[...]
* thread mono#5, name = 'Debugger agent', stop reason = signal SIGABRT
  * frame #0: 0x0000000190aedec4 libsystem_kernel.dylib`__pthread_kill + 8
    frame #1: 0x0000000190a0d724 libsystem_pthread.dylib`pthread_kill$VARIANT$armv81 + 216
    frame #2: 0x000000019095d844 libsystem_c.dylib`abort + 100
    frame mono#3: 0x00000001045871b4 reloadcontext.iOS`log_callback(log_domain=0x0000000000000000, log_level="error", message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", fatal=4, user_data=0x0000000000000000) at runtime.m:1213:3
    frame mono#4: 0x0000000104544fc8 reloadcontext.iOS`eglib_log_adapter(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", user_data=0x0000000000000000) at mono-logger.c:405:2
    frame mono#5: 0x000000010456093c reloadcontext.iOS`monoeg_g_logstr(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, msg="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n") at goutput.c:134:2
    frame mono#6: 0x0000000104560598 reloadcontext.iOS`monoeg_g_logv_nofree(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, format="* Assertion at %s:%d, condition `%s' not met\n", args="e\x12z\x04\x01") at goutput.c:149:2
    frame mono#7: 0x000000010456061c reloadcontext.iOS`monoeg_assertion_message(format="* Assertion at %s:%d, condition `%s' not met\n") at goutput.c:184:22
    frame mono#8: 0x0000000104560674 reloadcontext.iOS`mono_assertion_message(file="../../../../../mono/mini/interp/interp.c", line=7176, condition="context") at goutput.c:203:2
    frame mono#9: 0x000000010459b570 reloadcontext.iOS`interp_get_resume_state(jit_tls=0x000000014900d000, has_resume_state=0x000000016fc7a9f4, interp_frame=0x000000016fc7a9e8, handler_ip=0x000000016fc7a9e0) at interp.c:7176:2
    frame mono#10: 0x0000000104319420 reloadcontext.iOS`compute_frame_info(thread=0x0000000104fe4130, tls=0x0000000149014e00, force_update=1) at debugger-agent.c:3422:3
    frame mono#11: 0x0000000104320d40 reloadcontext.iOS`thread_commands(command=1, p="", end="", buf=0x000000016fc7acf8) at debugger-agent.c:9048:3
    frame mono#12: 0x000000010431cca0 reloadcontext.iOS`debugger_thread(arg=0x0000000000000000) at debugger-agent.c:10132:10
    frame mono#13: 0x000000010447eb04 reloadcontext.iOS`start_wrapper_internal(start_info=0x0000000000000000, stack_ptr=0x000000016fc7b000) at threads.c:1232:3
    frame mono#14: 0x000000010447e788 reloadcontext.iOS`start_wrapper(data=0x000000028203ef40) at threads.c:1305:8
    frame mono#15: 0x0000000190a11d8c libsystem_pthread.dylib`_pthread_start + 15
[...]
```

Thanks to @drasticactions for helping me to reproduce.

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1050615
monojenkins pushed a commit to monojenkins/mono that referenced this pull request Jan 22, 2020
`jit_tls->interp_context` gets initialized lazily, that is, upon the first interpreter execution on a specific thread (e.g. via interp_runtime_invoke). However, with mixed mode the execution can purely happen in AOT code upon the first interaction with the managed debugger.

Stack trace:

```
  thread mono#1, name = 'tid_407', queue = 'com.apple.main-thread'
    frame #0: 0x0000000190aedc94 libsystem_kernel.dylib`__psynch_cvwait + 8
    frame mono#1: 0x0000000190a0f094 libsystem_pthread.dylib`_pthread_cond_wait$VARIANT$armv81 + 672
    frame mono#2: 0x000000010431318c reloadcontext.iOS`mono_os_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-os-mutex.h:219:8
    frame mono#3: 0x0000000104312a68 reloadcontext.iOS`mono_coop_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-coop-mutex.h:91:2
    frame mono#4: 0x0000000104312858 reloadcontext.iOS`suspend_current at debugger-agent.c:3021:4
    frame mono#5: 0x000000010431be18 reloadcontext.iOS`process_event(event=EVENT_KIND_BREAKPOINT, arg=0x0000000145d09ae8, il_offset=0, ctx=0x0000000149015c20, events=0x0000000000000000, suspend_policy=2) at debugger-agent.c:4058:3
    frame mono#6: 0x0000000104310cf4 reloadcontext.iOS`process_breakpoint_events(_evts=0x000000028351a680, method=0x0000000145d09ae8, ctx=0x0000000149015c20, il_offset=0) at debugger-agent.c:4722:3
    frame mono#7: 0x000000010432f1c8 reloadcontext.iOS`mono_de_process_breakpoint(void_tls=0x0000000149014e00, from_signal=0) at debugger-engine.c:1141:2
    frame mono#8: 0x000000010430f238 reloadcontext.iOS`debugger_agent_breakpoint_from_context(ctx=0x000000016f656790) at debugger-agent.c:4938:2
    frame mono#9: 0x00000001011b73a4 reloadcontext.iOS`sdb_breakpoint_trampoline + 148
    frame mono#10: 0x00000001008511b4 reloadcontext.iOS`reloadcontext_iOS_Application_Main_string__(args=0x000000010703a030) at Main.cs:14
    frame mono#11: 0x00000001010f9730 reloadcontext.iOS`wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr + 272
    frame mono#12: 0x00000001042fd8b8 reloadcontext.iOS`mono_jit_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at mini-runtime.c:3162:3
    frame mono#13: 0x0000000104411950 reloadcontext.iOS`do_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at object.c:3052:11
    frame mono#14: 0x000000010440c4dc reloadcontext.iOS`mono_runtime_invoke_checked(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, error=0x000000016f656ff8) at object.c:3220:9
    frame mono#15: 0x0000000104415ae0 reloadcontext.iOS`do_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5184:3
    frame mono#16: 0x00000001044144ac reloadcontext.iOS`mono_runtime_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5281:9
    frame mono#17: 0x0000000104414500 reloadcontext.iOS`mono_runtime_run_main_checked(method=0x0000000145d09ae8, argc=1, argv=0x000000016f6570d0, error=0x000000016f656ff8) at object.c:4734:9
    frame mono#18: 0x00000001042d3b54 reloadcontext.iOS`mono_jit_exec_internal(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1320:13
    frame mono#19: 0x00000001042d39a4 reloadcontext.iOS`mono_jit_exec(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1265:7
    frame mono#20: 0x0000000104597994 reloadcontext.iOS`::xamarin_main(argc=5, argv=0x000000016f657a80, launch_mode=XamarinLaunchModeApp) at monotouch-main.m:483:8
    frame mono#21: 0x00000001008510dc reloadcontext.iOS`main(argc=5, argv=0x000000016f657a80) at main.m:104:11
    frame mono#22: 0x0000000190af8360 libdyld.dylib`start + 4
[...]
* thread mono#5, name = 'Debugger agent', stop reason = signal SIGABRT
  * frame #0: 0x0000000190aedec4 libsystem_kernel.dylib`__pthread_kill + 8
    frame mono#1: 0x0000000190a0d724 libsystem_pthread.dylib`pthread_kill$VARIANT$armv81 + 216
    frame mono#2: 0x000000019095d844 libsystem_c.dylib`abort + 100
    frame mono#3: 0x00000001045871b4 reloadcontext.iOS`log_callback(log_domain=0x0000000000000000, log_level="error", message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", fatal=4, user_data=0x0000000000000000) at runtime.m:1213:3
    frame mono#4: 0x0000000104544fc8 reloadcontext.iOS`eglib_log_adapter(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", user_data=0x0000000000000000) at mono-logger.c:405:2
    frame mono#5: 0x000000010456093c reloadcontext.iOS`monoeg_g_logstr(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, msg="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n") at goutput.c:134:2
    frame mono#6: 0x0000000104560598 reloadcontext.iOS`monoeg_g_logv_nofree(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, format="* Assertion at %s:%d, condition `%s' not met\n", args="e\x12z\x04\x01") at goutput.c:149:2
    frame mono#7: 0x000000010456061c reloadcontext.iOS`monoeg_assertion_message(format="* Assertion at %s:%d, condition `%s' not met\n") at goutput.c:184:22
    frame mono#8: 0x0000000104560674 reloadcontext.iOS`mono_assertion_message(file="../../../../../mono/mini/interp/interp.c", line=7176, condition="context") at goutput.c:203:2
    frame mono#9: 0x000000010459b570 reloadcontext.iOS`interp_get_resume_state(jit_tls=0x000000014900d000, has_resume_state=0x000000016fc7a9f4, interp_frame=0x000000016fc7a9e8, handler_ip=0x000000016fc7a9e0) at interp.c:7176:2
    frame mono#10: 0x0000000104319420 reloadcontext.iOS`compute_frame_info(thread=0x0000000104fe4130, tls=0x0000000149014e00, force_update=1) at debugger-agent.c:3422:3
    frame mono#11: 0x0000000104320d40 reloadcontext.iOS`thread_commands(command=1, p="", end="", buf=0x000000016fc7acf8) at debugger-agent.c:9048:3
    frame mono#12: 0x000000010431cca0 reloadcontext.iOS`debugger_thread(arg=0x0000000000000000) at debugger-agent.c:10132:10
    frame mono#13: 0x000000010447eb04 reloadcontext.iOS`start_wrapper_internal(start_info=0x0000000000000000, stack_ptr=0x000000016fc7b000) at threads.c:1232:3
    frame mono#14: 0x000000010447e788 reloadcontext.iOS`start_wrapper(data=0x000000028203ef40) at threads.c:1305:8
    frame mono#15: 0x0000000190a11d8c libsystem_pthread.dylib`_pthread_start + 15
[...]
```

Thanks to @drasticactions for helping me to reproduce.

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1050615
monojenkins pushed a commit to monojenkins/mono that referenced this pull request Jan 22, 2020
`jit_tls->interp_context` gets initialized lazily, that is, upon the first interpreter execution on a specific thread (e.g. via interp_runtime_invoke). However, with mixed mode the execution can purely happen in AOT code upon the first interaction with the managed debugger.

Stack trace:

```
  thread mono#1, name = 'tid_407', queue = 'com.apple.main-thread'
    frame #0: 0x0000000190aedc94 libsystem_kernel.dylib`__psynch_cvwait + 8
    frame mono#1: 0x0000000190a0f094 libsystem_pthread.dylib`_pthread_cond_wait$VARIANT$armv81 + 672
    frame mono#2: 0x000000010431318c reloadcontext.iOS`mono_os_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-os-mutex.h:219:8
    frame mono#3: 0x0000000104312a68 reloadcontext.iOS`mono_coop_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-coop-mutex.h:91:2
    frame mono#4: 0x0000000104312858 reloadcontext.iOS`suspend_current at debugger-agent.c:3021:4
    frame mono#5: 0x000000010431be18 reloadcontext.iOS`process_event(event=EVENT_KIND_BREAKPOINT, arg=0x0000000145d09ae8, il_offset=0, ctx=0x0000000149015c20, events=0x0000000000000000, suspend_policy=2) at debugger-agent.c:4058:3
    frame mono#6: 0x0000000104310cf4 reloadcontext.iOS`process_breakpoint_events(_evts=0x000000028351a680, method=0x0000000145d09ae8, ctx=0x0000000149015c20, il_offset=0) at debugger-agent.c:4722:3
    frame mono#7: 0x000000010432f1c8 reloadcontext.iOS`mono_de_process_breakpoint(void_tls=0x0000000149014e00, from_signal=0) at debugger-engine.c:1141:2
    frame mono#8: 0x000000010430f238 reloadcontext.iOS`debugger_agent_breakpoint_from_context(ctx=0x000000016f656790) at debugger-agent.c:4938:2
    frame mono#9: 0x00000001011b73a4 reloadcontext.iOS`sdb_breakpoint_trampoline + 148
    frame mono#10: 0x00000001008511b4 reloadcontext.iOS`reloadcontext_iOS_Application_Main_string__(args=0x000000010703a030) at Main.cs:14
    frame mono#11: 0x00000001010f9730 reloadcontext.iOS`wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr + 272
    frame mono#12: 0x00000001042fd8b8 reloadcontext.iOS`mono_jit_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at mini-runtime.c:3162:3
    frame mono#13: 0x0000000104411950 reloadcontext.iOS`do_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at object.c:3052:11
    frame mono#14: 0x000000010440c4dc reloadcontext.iOS`mono_runtime_invoke_checked(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, error=0x000000016f656ff8) at object.c:3220:9
    frame mono#15: 0x0000000104415ae0 reloadcontext.iOS`do_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5184:3
    frame mono#16: 0x00000001044144ac reloadcontext.iOS`mono_runtime_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5281:9
    frame mono#17: 0x0000000104414500 reloadcontext.iOS`mono_runtime_run_main_checked(method=0x0000000145d09ae8, argc=1, argv=0x000000016f6570d0, error=0x000000016f656ff8) at object.c:4734:9
    frame mono#18: 0x00000001042d3b54 reloadcontext.iOS`mono_jit_exec_internal(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1320:13
    frame mono#19: 0x00000001042d39a4 reloadcontext.iOS`mono_jit_exec(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1265:7
    frame mono#20: 0x0000000104597994 reloadcontext.iOS`::xamarin_main(argc=5, argv=0x000000016f657a80, launch_mode=XamarinLaunchModeApp) at monotouch-main.m:483:8
    frame mono#21: 0x00000001008510dc reloadcontext.iOS`main(argc=5, argv=0x000000016f657a80) at main.m:104:11
    frame mono#22: 0x0000000190af8360 libdyld.dylib`start + 4
[...]
* thread mono#5, name = 'Debugger agent', stop reason = signal SIGABRT
  * frame #0: 0x0000000190aedec4 libsystem_kernel.dylib`__pthread_kill + 8
    frame mono#1: 0x0000000190a0d724 libsystem_pthread.dylib`pthread_kill$VARIANT$armv81 + 216
    frame mono#2: 0x000000019095d844 libsystem_c.dylib`abort + 100
    frame mono#3: 0x00000001045871b4 reloadcontext.iOS`log_callback(log_domain=0x0000000000000000, log_level="error", message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", fatal=4, user_data=0x0000000000000000) at runtime.m:1213:3
    frame mono#4: 0x0000000104544fc8 reloadcontext.iOS`eglib_log_adapter(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", user_data=0x0000000000000000) at mono-logger.c:405:2
    frame mono#5: 0x000000010456093c reloadcontext.iOS`monoeg_g_logstr(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, msg="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n") at goutput.c:134:2
    frame mono#6: 0x0000000104560598 reloadcontext.iOS`monoeg_g_logv_nofree(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, format="* Assertion at %s:%d, condition `%s' not met\n", args="e\x12z\x04\x01") at goutput.c:149:2
    frame mono#7: 0x000000010456061c reloadcontext.iOS`monoeg_assertion_message(format="* Assertion at %s:%d, condition `%s' not met\n") at goutput.c:184:22
    frame mono#8: 0x0000000104560674 reloadcontext.iOS`mono_assertion_message(file="../../../../../mono/mini/interp/interp.c", line=7176, condition="context") at goutput.c:203:2
    frame mono#9: 0x000000010459b570 reloadcontext.iOS`interp_get_resume_state(jit_tls=0x000000014900d000, has_resume_state=0x000000016fc7a9f4, interp_frame=0x000000016fc7a9e8, handler_ip=0x000000016fc7a9e0) at interp.c:7176:2
    frame mono#10: 0x0000000104319420 reloadcontext.iOS`compute_frame_info(thread=0x0000000104fe4130, tls=0x0000000149014e00, force_update=1) at debugger-agent.c:3422:3
    frame mono#11: 0x0000000104320d40 reloadcontext.iOS`thread_commands(command=1, p="", end="", buf=0x000000016fc7acf8) at debugger-agent.c:9048:3
    frame mono#12: 0x000000010431cca0 reloadcontext.iOS`debugger_thread(arg=0x0000000000000000) at debugger-agent.c:10132:10
    frame mono#13: 0x000000010447eb04 reloadcontext.iOS`start_wrapper_internal(start_info=0x0000000000000000, stack_ptr=0x000000016fc7b000) at threads.c:1232:3
    frame mono#14: 0x000000010447e788 reloadcontext.iOS`start_wrapper(data=0x000000028203ef40) at threads.c:1305:8
    frame mono#15: 0x0000000190a11d8c libsystem_pthread.dylib`_pthread_start + 15
[...]
```

Thanks to @drasticactions for helping me to reproduce.

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1050615
lewurm added a commit that referenced this pull request Jan 23, 2020
…18535)

`jit_tls->interp_context` gets initialized lazily, that is, upon the first interpreter execution on a specific thread (e.g. via interp_runtime_invoke). However, with mixed mode the execution can purely happen in AOT code upon the first interaction with the managed debugger.

Stack trace:

```
  thread #1, name = 'tid_407', queue = 'com.apple.main-thread'
    frame #0: 0x0000000190aedc94 libsystem_kernel.dylib`__psynch_cvwait + 8
    frame #1: 0x0000000190a0f094 libsystem_pthread.dylib`_pthread_cond_wait$VARIANT$armv81 + 672
    frame #2: 0x000000010431318c reloadcontext.iOS`mono_os_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-os-mutex.h:219:8
    frame #3: 0x0000000104312a68 reloadcontext.iOS`mono_coop_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-coop-mutex.h:91:2
    frame #4: 0x0000000104312858 reloadcontext.iOS`suspend_current at debugger-agent.c:3021:4
    frame #5: 0x000000010431be18 reloadcontext.iOS`process_event(event=EVENT_KIND_BREAKPOINT, arg=0x0000000145d09ae8, il_offset=0, ctx=0x0000000149015c20, events=0x0000000000000000, suspend_policy=2) at debugger-agent.c:4058:3
    frame #6: 0x0000000104310cf4 reloadcontext.iOS`process_breakpoint_events(_evts=0x000000028351a680, method=0x0000000145d09ae8, ctx=0x0000000149015c20, il_offset=0) at debugger-agent.c:4722:3
    frame #7: 0x000000010432f1c8 reloadcontext.iOS`mono_de_process_breakpoint(void_tls=0x0000000149014e00, from_signal=0) at debugger-engine.c:1141:2
    frame #8: 0x000000010430f238 reloadcontext.iOS`debugger_agent_breakpoint_from_context(ctx=0x000000016f656790) at debugger-agent.c:4938:2
    frame #9: 0x00000001011b73a4 reloadcontext.iOS`sdb_breakpoint_trampoline + 148
    frame #10: 0x00000001008511b4 reloadcontext.iOS`reloadcontext_iOS_Application_Main_string__(args=0x000000010703a030) at Main.cs:14
    frame #11: 0x00000001010f9730 reloadcontext.iOS`wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr + 272
    frame #12: 0x00000001042fd8b8 reloadcontext.iOS`mono_jit_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at mini-runtime.c:3162:3
    frame #13: 0x0000000104411950 reloadcontext.iOS`do_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at object.c:3052:11
    frame #14: 0x000000010440c4dc reloadcontext.iOS`mono_runtime_invoke_checked(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, error=0x000000016f656ff8) at object.c:3220:9
    frame #15: 0x0000000104415ae0 reloadcontext.iOS`do_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5184:3
    frame #16: 0x00000001044144ac reloadcontext.iOS`mono_runtime_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5281:9
    frame #17: 0x0000000104414500 reloadcontext.iOS`mono_runtime_run_main_checked(method=0x0000000145d09ae8, argc=1, argv=0x000000016f6570d0, error=0x000000016f656ff8) at object.c:4734:9
    frame #18: 0x00000001042d3b54 reloadcontext.iOS`mono_jit_exec_internal(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1320:13
    frame #19: 0x00000001042d39a4 reloadcontext.iOS`mono_jit_exec(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1265:7
    frame #20: 0x0000000104597994 reloadcontext.iOS`::xamarin_main(argc=5, argv=0x000000016f657a80, launch_mode=XamarinLaunchModeApp) at monotouch-main.m:483:8
    frame #21: 0x00000001008510dc reloadcontext.iOS`main(argc=5, argv=0x000000016f657a80) at main.m:104:11
    frame #22: 0x0000000190af8360 libdyld.dylib`start + 4
[...]
* thread #5, name = 'Debugger agent', stop reason = signal SIGABRT
  * frame #0: 0x0000000190aedec4 libsystem_kernel.dylib`__pthread_kill + 8
    frame #1: 0x0000000190a0d724 libsystem_pthread.dylib`pthread_kill$VARIANT$armv81 + 216
    frame #2: 0x000000019095d844 libsystem_c.dylib`abort + 100
    frame #3: 0x00000001045871b4 reloadcontext.iOS`log_callback(log_domain=0x0000000000000000, log_level="error", message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", fatal=4, user_data=0x0000000000000000) at runtime.m:1213:3
    frame #4: 0x0000000104544fc8 reloadcontext.iOS`eglib_log_adapter(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", user_data=0x0000000000000000) at mono-logger.c:405:2
    frame #5: 0x000000010456093c reloadcontext.iOS`monoeg_g_logstr(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, msg="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n") at goutput.c:134:2
    frame #6: 0x0000000104560598 reloadcontext.iOS`monoeg_g_logv_nofree(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, format="* Assertion at %s:%d, condition `%s' not met\n", args="e\x12z\x04\x01") at goutput.c:149:2
    frame #7: 0x000000010456061c reloadcontext.iOS`monoeg_assertion_message(format="* Assertion at %s:%d, condition `%s' not met\n") at goutput.c:184:22
    frame #8: 0x0000000104560674 reloadcontext.iOS`mono_assertion_message(file="../../../../../mono/mini/interp/interp.c", line=7176, condition="context") at goutput.c:203:2
    frame #9: 0x000000010459b570 reloadcontext.iOS`interp_get_resume_state(jit_tls=0x000000014900d000, has_resume_state=0x000000016fc7a9f4, interp_frame=0x000000016fc7a9e8, handler_ip=0x000000016fc7a9e0) at interp.c:7176:2
    frame #10: 0x0000000104319420 reloadcontext.iOS`compute_frame_info(thread=0x0000000104fe4130, tls=0x0000000149014e00, force_update=1) at debugger-agent.c:3422:3
    frame #11: 0x0000000104320d40 reloadcontext.iOS`thread_commands(command=1, p="", end="", buf=0x000000016fc7acf8) at debugger-agent.c:9048:3
    frame #12: 0x000000010431cca0 reloadcontext.iOS`debugger_thread(arg=0x0000000000000000) at debugger-agent.c:10132:10
    frame #13: 0x000000010447eb04 reloadcontext.iOS`start_wrapper_internal(start_info=0x0000000000000000, stack_ptr=0x000000016fc7b000) at threads.c:1232:3
    frame #14: 0x000000010447e788 reloadcontext.iOS`start_wrapper(data=0x000000028203ef40) at threads.c:1305:8
    frame #15: 0x0000000190a11d8c libsystem_pthread.dylib`_pthread_start + 15
[...]
```

Thanks to @drasticactions for helping me to reproduce.

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1050615

Co-authored-by: Bernhard Urban-Forster <bernhard.urban@xamarin.com>
lewurm added a commit that referenced this pull request Jan 23, 2020
…18533)

`jit_tls->interp_context` gets initialized lazily, that is, upon the first interpreter execution on a specific thread (e.g. via interp_runtime_invoke). However, with mixed mode the execution can purely happen in AOT code upon the first interaction with the managed debugger.

Stack trace:

```
  thread #1, name = 'tid_407', queue = 'com.apple.main-thread'
    frame #0: 0x0000000190aedc94 libsystem_kernel.dylib`__psynch_cvwait + 8
    frame #1: 0x0000000190a0f094 libsystem_pthread.dylib`_pthread_cond_wait$VARIANT$armv81 + 672
    frame #2: 0x000000010431318c reloadcontext.iOS`mono_os_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-os-mutex.h:219:8
    frame #3: 0x0000000104312a68 reloadcontext.iOS`mono_coop_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-coop-mutex.h:91:2
    frame #4: 0x0000000104312858 reloadcontext.iOS`suspend_current at debugger-agent.c:3021:4
    frame #5: 0x000000010431be18 reloadcontext.iOS`process_event(event=EVENT_KIND_BREAKPOINT, arg=0x0000000145d09ae8, il_offset=0, ctx=0x0000000149015c20, events=0x0000000000000000, suspend_policy=2) at debugger-agent.c:4058:3
    frame #6: 0x0000000104310cf4 reloadcontext.iOS`process_breakpoint_events(_evts=0x000000028351a680, method=0x0000000145d09ae8, ctx=0x0000000149015c20, il_offset=0) at debugger-agent.c:4722:3
    frame #7: 0x000000010432f1c8 reloadcontext.iOS`mono_de_process_breakpoint(void_tls=0x0000000149014e00, from_signal=0) at debugger-engine.c:1141:2
    frame #8: 0x000000010430f238 reloadcontext.iOS`debugger_agent_breakpoint_from_context(ctx=0x000000016f656790) at debugger-agent.c:4938:2
    frame #9: 0x00000001011b73a4 reloadcontext.iOS`sdb_breakpoint_trampoline + 148
    frame #10: 0x00000001008511b4 reloadcontext.iOS`reloadcontext_iOS_Application_Main_string__(args=0x000000010703a030) at Main.cs:14
    frame #11: 0x00000001010f9730 reloadcontext.iOS`wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr + 272
    frame #12: 0x00000001042fd8b8 reloadcontext.iOS`mono_jit_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at mini-runtime.c:3162:3
    frame #13: 0x0000000104411950 reloadcontext.iOS`do_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at object.c:3052:11
    frame #14: 0x000000010440c4dc reloadcontext.iOS`mono_runtime_invoke_checked(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, error=0x000000016f656ff8) at object.c:3220:9
    frame #15: 0x0000000104415ae0 reloadcontext.iOS`do_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5184:3
    frame #16: 0x00000001044144ac reloadcontext.iOS`mono_runtime_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5281:9
    frame #17: 0x0000000104414500 reloadcontext.iOS`mono_runtime_run_main_checked(method=0x0000000145d09ae8, argc=1, argv=0x000000016f6570d0, error=0x000000016f656ff8) at object.c:4734:9
    frame #18: 0x00000001042d3b54 reloadcontext.iOS`mono_jit_exec_internal(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1320:13
    frame #19: 0x00000001042d39a4 reloadcontext.iOS`mono_jit_exec(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1265:7
    frame #20: 0x0000000104597994 reloadcontext.iOS`::xamarin_main(argc=5, argv=0x000000016f657a80, launch_mode=XamarinLaunchModeApp) at monotouch-main.m:483:8
    frame #21: 0x00000001008510dc reloadcontext.iOS`main(argc=5, argv=0x000000016f657a80) at main.m:104:11
    frame #22: 0x0000000190af8360 libdyld.dylib`start + 4
[...]
* thread #5, name = 'Debugger agent', stop reason = signal SIGABRT
  * frame #0: 0x0000000190aedec4 libsystem_kernel.dylib`__pthread_kill + 8
    frame #1: 0x0000000190a0d724 libsystem_pthread.dylib`pthread_kill$VARIANT$armv81 + 216
    frame #2: 0x000000019095d844 libsystem_c.dylib`abort + 100
    frame #3: 0x00000001045871b4 reloadcontext.iOS`log_callback(log_domain=0x0000000000000000, log_level="error", message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", fatal=4, user_data=0x0000000000000000) at runtime.m:1213:3
    frame #4: 0x0000000104544fc8 reloadcontext.iOS`eglib_log_adapter(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", user_data=0x0000000000000000) at mono-logger.c:405:2
    frame #5: 0x000000010456093c reloadcontext.iOS`monoeg_g_logstr(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, msg="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n") at goutput.c:134:2
    frame #6: 0x0000000104560598 reloadcontext.iOS`monoeg_g_logv_nofree(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, format="* Assertion at %s:%d, condition `%s' not met\n", args="e\x12z\x04\x01") at goutput.c:149:2
    frame #7: 0x000000010456061c reloadcontext.iOS`monoeg_assertion_message(format="* Assertion at %s:%d, condition `%s' not met\n") at goutput.c:184:22
    frame #8: 0x0000000104560674 reloadcontext.iOS`mono_assertion_message(file="../../../../../mono/mini/interp/interp.c", line=7176, condition="context") at goutput.c:203:2
    frame #9: 0x000000010459b570 reloadcontext.iOS`interp_get_resume_state(jit_tls=0x000000014900d000, has_resume_state=0x000000016fc7a9f4, interp_frame=0x000000016fc7a9e8, handler_ip=0x000000016fc7a9e0) at interp.c:7176:2
    frame #10: 0x0000000104319420 reloadcontext.iOS`compute_frame_info(thread=0x0000000104fe4130, tls=0x0000000149014e00, force_update=1) at debugger-agent.c:3422:3
    frame #11: 0x0000000104320d40 reloadcontext.iOS`thread_commands(command=1, p="", end="", buf=0x000000016fc7acf8) at debugger-agent.c:9048:3
    frame #12: 0x000000010431cca0 reloadcontext.iOS`debugger_thread(arg=0x0000000000000000) at debugger-agent.c:10132:10
    frame #13: 0x000000010447eb04 reloadcontext.iOS`start_wrapper_internal(start_info=0x0000000000000000, stack_ptr=0x000000016fc7b000) at threads.c:1232:3
    frame #14: 0x000000010447e788 reloadcontext.iOS`start_wrapper(data=0x000000028203ef40) at threads.c:1305:8
    frame #15: 0x0000000190a11d8c libsystem_pthread.dylib`_pthread_start + 15
[...]
```

Thanks to @drasticactions for helping me to reproduce.

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1050615
lewurm added a commit that referenced this pull request Jan 24, 2020
…18536)

`jit_tls->interp_context` gets initialized lazily, that is, upon the first interpreter execution on a specific thread (e.g. via interp_runtime_invoke). However, with mixed mode the execution can purely happen in AOT code upon the first interaction with the managed debugger.

Stack trace:

```
  thread #1, name = 'tid_407', queue = 'com.apple.main-thread'
    frame #0: 0x0000000190aedc94 libsystem_kernel.dylib`__psynch_cvwait + 8
    frame #1: 0x0000000190a0f094 libsystem_pthread.dylib`_pthread_cond_wait$VARIANT$armv81 + 672
    frame #2: 0x000000010431318c reloadcontext.iOS`mono_os_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-os-mutex.h:219:8
    frame #3: 0x0000000104312a68 reloadcontext.iOS`mono_coop_cond_wait(cond=0x0000000104b9ba78, mutex=0x0000000104b9ba30) at mono-coop-mutex.h:91:2
    frame #4: 0x0000000104312858 reloadcontext.iOS`suspend_current at debugger-agent.c:3021:4
    frame #5: 0x000000010431be18 reloadcontext.iOS`process_event(event=EVENT_KIND_BREAKPOINT, arg=0x0000000145d09ae8, il_offset=0, ctx=0x0000000149015c20, events=0x0000000000000000, suspend_policy=2) at debugger-agent.c:4058:3
    frame #6: 0x0000000104310cf4 reloadcontext.iOS`process_breakpoint_events(_evts=0x000000028351a680, method=0x0000000145d09ae8, ctx=0x0000000149015c20, il_offset=0) at debugger-agent.c:4722:3
    frame #7: 0x000000010432f1c8 reloadcontext.iOS`mono_de_process_breakpoint(void_tls=0x0000000149014e00, from_signal=0) at debugger-engine.c:1141:2
    frame #8: 0x000000010430f238 reloadcontext.iOS`debugger_agent_breakpoint_from_context(ctx=0x000000016f656790) at debugger-agent.c:4938:2
    frame #9: 0x00000001011b73a4 reloadcontext.iOS`sdb_breakpoint_trampoline + 148
    frame #10: 0x00000001008511b4 reloadcontext.iOS`reloadcontext_iOS_Application_Main_string__(args=0x000000010703a030) at Main.cs:14
    frame #11: 0x00000001010f9730 reloadcontext.iOS`wrapper_runtime_invoke_object_runtime_invoke_dynamic_intptr_intptr_intptr_intptr + 272
    frame #12: 0x00000001042fd8b8 reloadcontext.iOS`mono_jit_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at mini-runtime.c:3162:3
    frame #13: 0x0000000104411950 reloadcontext.iOS`do_runtime_invoke(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, exc=0x0000000000000000, error=0x000000016f656ff8) at object.c:3052:11
    frame #14: 0x000000010440c4dc reloadcontext.iOS`mono_runtime_invoke_checked(method=0x0000000145d09ae8, obj=0x0000000000000000, params=0x000000016f656f20, error=0x000000016f656ff8) at object.c:3220:9
    frame #15: 0x0000000104415ae0 reloadcontext.iOS`do_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5184:3
    frame #16: 0x00000001044144ac reloadcontext.iOS`mono_runtime_exec_main_checked(method=0x0000000145d09ae8, args=0x000000010703a030, error=0x000000016f656ff8) at object.c:5281:9
    frame #17: 0x0000000104414500 reloadcontext.iOS`mono_runtime_run_main_checked(method=0x0000000145d09ae8, argc=1, argv=0x000000016f6570d0, error=0x000000016f656ff8) at object.c:4734:9
    frame #18: 0x00000001042d3b54 reloadcontext.iOS`mono_jit_exec_internal(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1320:13
    frame #19: 0x00000001042d39a4 reloadcontext.iOS`mono_jit_exec(domain=0x0000000145f00130, assembly=0x0000000281ba2900, argc=1, argv=0x000000016f6570d0) at driver.c:1265:7
    frame #20: 0x0000000104597994 reloadcontext.iOS`::xamarin_main(argc=5, argv=0x000000016f657a80, launch_mode=XamarinLaunchModeApp) at monotouch-main.m:483:8
    frame #21: 0x00000001008510dc reloadcontext.iOS`main(argc=5, argv=0x000000016f657a80) at main.m:104:11
    frame #22: 0x0000000190af8360 libdyld.dylib`start + 4
[...]
* thread #5, name = 'Debugger agent', stop reason = signal SIGABRT
  * frame #0: 0x0000000190aedec4 libsystem_kernel.dylib`__pthread_kill + 8
    frame #1: 0x0000000190a0d724 libsystem_pthread.dylib`pthread_kill$VARIANT$armv81 + 216
    frame #2: 0x000000019095d844 libsystem_c.dylib`abort + 100
    frame #3: 0x00000001045871b4 reloadcontext.iOS`log_callback(log_domain=0x0000000000000000, log_level="error", message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", fatal=4, user_data=0x0000000000000000) at runtime.m:1213:3
    frame #4: 0x0000000104544fc8 reloadcontext.iOS`eglib_log_adapter(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, message="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n", user_data=0x0000000000000000) at mono-logger.c:405:2
    frame #5: 0x000000010456093c reloadcontext.iOS`monoeg_g_logstr(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, msg="* Assertion at ../../../../../mono/mini/interp/interp.c:7176, condition `context' not met\n") at goutput.c:134:2
    frame #6: 0x0000000104560598 reloadcontext.iOS`monoeg_g_logv_nofree(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, format="* Assertion at %s:%d, condition `%s' not met\n", args="e\x12z\x04\x01") at goutput.c:149:2
    frame #7: 0x000000010456061c reloadcontext.iOS`monoeg_assertion_message(format="* Assertion at %s:%d, condition `%s' not met\n") at goutput.c:184:22
    frame #8: 0x0000000104560674 reloadcontext.iOS`mono_assertion_message(file="../../../../../mono/mini/interp/interp.c", line=7176, condition="context") at goutput.c:203:2
    frame #9: 0x000000010459b570 reloadcontext.iOS`interp_get_resume_state(jit_tls=0x000000014900d000, has_resume_state=0x000000016fc7a9f4, interp_frame=0x000000016fc7a9e8, handler_ip=0x000000016fc7a9e0) at interp.c:7176:2
    frame #10: 0x0000000104319420 reloadcontext.iOS`compute_frame_info(thread=0x0000000104fe4130, tls=0x0000000149014e00, force_update=1) at debugger-agent.c:3422:3
    frame #11: 0x0000000104320d40 reloadcontext.iOS`thread_commands(command=1, p="", end="", buf=0x000000016fc7acf8) at debugger-agent.c:9048:3
    frame #12: 0x000000010431cca0 reloadcontext.iOS`debugger_thread(arg=0x0000000000000000) at debugger-agent.c:10132:10
    frame #13: 0x000000010447eb04 reloadcontext.iOS`start_wrapper_internal(start_info=0x0000000000000000, stack_ptr=0x000000016fc7b000) at threads.c:1232:3
    frame #14: 0x000000010447e788 reloadcontext.iOS`start_wrapper(data=0x000000028203ef40) at threads.c:1305:8
    frame #15: 0x0000000190a11d8c libsystem_pthread.dylib`_pthread_start + 15
[...]
```

Thanks to @drasticactions for helping me to reproduce.

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1050615

Co-authored-by: Bernhard Urban-Forster <bernhard.urban@xamarin.com>
@thenapster thenapster mentioned this pull request Aug 18, 2021
picenka21 pushed a commit to picenka21/runtime that referenced this pull request Feb 18, 2022
We would previously observe the following crash:

```
ludovic-laptop :: ~/Xamarin/mono ‹16c07b5› » (cd tools/pedump && MONO_PATH=../../mcs/class/lib/net_4_x lldb -- ./pedump --verify metadata,code ../.././mono/tests/xdomain-threads.exe)
(lldb) target create "./pedump"
Current executable set to './pedump' (x86_64).
(lldb) settings set -- target.run-args  "--verify" "metadata,code" "../.././mono/tests/xdomain-threads.exe"
(lldb) r
Process 14407 launched: './pedump' (x86_64)
mono_os_mutex_lock: pthread_mutex_lock failed with "Invalid argument" (22)
Process 14407 stopped
* thread mono/mono#1: tid = 0x27c9715, 0x00007fff93cfcf06 libsystem_kernel.dylib`__pthread_kill + 10, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
    frame mono/mono#0: 0x00007fff93cfcf06 libsystem_kernel.dylib`__pthread_kill + 10
	libsystem_kernel.dylib`__pthread_kill:
	->  0x7fff93cfcf06 <+10>: jae    0x7fff93cfcf10            ; <+20>
	    0x7fff93cfcf08 <+12>: movq   %rax, %rdi
        0x7fff93cfcf0b <+15>: jmp    0x7fff93cf77cd            ; cerror_nocancel
	    0x7fff93cfcf10 <+20>: retq
(lldb) bt
* thread mono/mono#1: tid = 0x27c9715, 0x00007fff93cfcf06 libsystem_kernel.dylib`__pthread_kill + 10, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
  * frame mono/mono#0: 0x00007fff93cfcf06 libsystem_kernel.dylib`__pthread_kill + 10
    frame mono/mono#1: 0x00007fff8b9b74ec libsystem_pthread.dylib`pthread_kill + 90
	frame mono/mono#2: 0x00007fff908d56e7 libsystem_c.dylib`abort + 129
	frame mono/mono#3: 0x000000010022da6a pedump`monoeg_log_default_handler(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, message="mono_os_mutex_lock: pthread_mutex_lock failed with \"Invalid argument\" (22)", unused_data=0x0000000000000000) + 202 at goutput.c:231
	frame mono/mono#4: 0x000000010022d98d pedump`monoeg_g_logv(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, format="%s: pthread_mutex_lock failed with \"%s\" (%d)", args=0x00007fff5fbff4a0) + 109 at goutput.c:111
	frame mono/mono#5: 0x000000010022dbd9 pedump`monoeg_g_log(log_domain=0x0000000000000000, log_level=G_LOG_LEVEL_ERROR, format="%s: pthread_mutex_lock failed with \"%s\" (%d)") + 361 at goutput.c:121
	frame mono/mono#6: 0x000000010022301e pedump`mono_os_mutex_lock(mutex=0x00000001002ec630) + 110 at mono-os-mutex.h:98
	frame mono/mono#7: 0x0000000100223a66 pedump`mono_w32handle_new(type=MONO_W32HANDLE_PROCESS, handle_specific=0x00007fff5fbff540) + 246 at w32handle.c:440
	frame mono/mono#8: 0x00000001001ef8bb pedump`_wapi_processes_init + 123 at processes.c:1149
	frame mono/mono#9: 0x00000001001fbcc3 pedump`wapi_init + 19 at wapi.c:23
	frame mono/mono#10: 0x0000000100116486 pedump`mono_init_internal(filename="pedump", exe_filename=0x0000000000000000, runtime_version="v4.0.30319") + 102 at domain.c:528
	frame mono/mono#11: 0x0000000100117124 pedump`mono_init_version(domain_name="pedump", version="v4.0.30319") + 36 at domain.c:868
	frame mono/mono#12: 0x0000000100001496 pedump`verify_image_file(fname="../.././mono/tests/xdomain-threads.exe") + 678 at pedump.c:466
	frame mono/mono#13: 0x0000000100000f87 pedump`main(argc=4, argv=0x00007fff5fbff9a0) + 1095 at pedump.c:708
	frame mono/mono#14: 0x00007fff93e655ad libdyld.dylib`start + 1
```

That would be because the w32handle wouldn't be initialized before calling into `wapi_init` which allocates w32handle.


Commit migrated from mono/mono@e8a2216
picenka21 pushed a commit to picenka21/runtime that referenced this pull request Feb 18, 2022
We would observe crashes like the following:

```
 * Assertion at mono-threads.c:1009, condition `mono_thread_info_run_state (info) == STATE_ASYNC_SUSPENDED' not met

 Debug info from gdb:

 [New LWP 26793]
 [New LWP 26792]
 [Thread debugging using libthread_db enabled]
 Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
 0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0
   Id   Target Id         Frame
   3    Thread 0x2b0ff3e6c700 (LWP 26792) "SGen worker" 0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
   2    Thread 0x2b0ff633e700 (LWP 26793) "Finalizer" 0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 * 1    Thread 0x2b0ff2b67c40 (LWP 26780) "mono" 0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0

 Thread 3 (Thread 0x2b0ff3e6c700 (LWP 26792)):
 mono/mono#0  0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 mono/mono#1  0x0000000000661bdf in mono_os_cond_wait (mutex=0x9dee40 <lock>, cond=0x9dee00 <work_cond>) at ../../mono/utils/mono-os-mutex.h:146
 mono/mono#2  thread_func (thread_data=0x2b0ff2bcb008) at sgen-thread-pool.c:129
 mono/mono#3  0x00002b0ff347a182 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
 mono/mono#4  0x00002b0ff39a130d in clone () from /lib/x86_64-linux-gnu/libc.so.6

 Thread 2 (Thread 0x2b0ff633e700 (LWP 26793)):
 mono/mono#0  0x00002b0ff347e414 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
 mono/mono#1  0x00000000005caff3 in mono_os_cond_wait (mutex=<optimized out>, cond=<optimized out>) at ../../mono/utils/mono-os-mutex.h:146
 mono/mono#2  mono_coop_cond_wait (mutex=<optimized out>, cond=<optimized out>) at ../../mono/utils/mono-coop-mutex.h:87
 mono/mono#3  mono_threadpool_io_remove_socket (fd=134239440) at threadpool-io.c:628
 mono/mono#4  0x00000000005ae4f4 in ves_icall_System_Net_Sockets_Socket_Close_internal (sock=42, werror=<optimized out>) at w32socket.c:708
 mono/mono#5  0x0000000041e8101f in ?? ()
 mono/mono#6  0x00002b1014abe070 in ?? ()
 mono/mono#7  0x0000000001615860 in ?? ()
 mono/mono#8  0x0000000001615860 in ?? ()
 mono/mono#9  0x0000000000000000 in ?? ()

 Thread 1 (Thread 0x2b0ff2b67c40 (LWP 26780)):
 mono/mono#0  0x00002b0ff3481ee9 in waitpid () from /lib/x86_64-linux-gnu/libpthread.so.0
 mono/mono#1  0x00000000004ac5e6 in mono_handle_native_crash (signal=<optimized out>, ctx=<optimized out>, info=<optimized out>) at mini-exceptions.c:2557
 mono/mono#2  <signal handler called>
 mono/mono#3  0x00002b0ff38dcf79 in raise () from /lib/x86_64-linux-gnu/libc.so.6
 mono/mono#4  0x00002b0ff38e0388 in abort () from /lib/x86_64-linux-gnu/libc.so.6
 mono/mono#5  0x000000000066b459 in mono_log_write_logfile (log_domain=<optimized out>, level=<optimized out>, hdr=<optimized out>, message=<optimized out>) at mono-log-common.c:137
 mono/mono#6  0x00000000006805e0 in monoeg_g_logv (log_domain=log_domain@entry=0x0, log_level=log_level@entry=G_LOG_LEVEL_ERROR, format=<optimized out>, args=args@entry=0x7ffc7324ea78) at goutput.c:115
 mono/mono#7  0x0000000000680736 in monoeg_assertion_message (format=<optimized out>) at goutput.c:135
 mono/mono#8  0x00000000006759b8 in mono_thread_info_setup_async_call (info=info@entry=0x2b0ff80008c0, target_func=target_func@entry=0x5bac20 <suspend_for_shutdown_async_call>, user_data=user_data@entry=0x0) at mono-threads.c:1009
 mono/mono#9  0x00000000005bad50 in suspend_for_shutdown_critical (info=info@entry=0x2b0ff80008c0, unused=unused@entry=0x0) at threads.c:5019
 mono/mono#10 0x00000000006763ae in mono_thread_info_safe_suspend_and_run (id=47347555100416, interrupt_kernel=interrupt_kernel@entry=0, callback=callback@entry=0x5bad40 <suspend_for_shutdown_critical>, user_data=user_data@entry=0x0) at mono-threads.c:979
 mono/mono#11 0x00000000005c2e71 in mono_thread_internal_suspend_for_shutdown (thread=<optimized out>) at threads.c:5028
 mono/mono#12 0x00000000005e9100 in mono_gc_cleanup () at gc.c:1015
 mono/mono#13 0x00000000005e108e in mono_runtime_cleanup (domain=domain@entry=0x1615860) at appdomain.c:423
 mono/mono#14 0x00000000004228cb in mini_cleanup (domain=0x1615860) at mini-runtime.c:4111
 mono/mono#15 0x000000000047b99f in mono_main (argc=10, argv=<optimized out>) at driver.c:2167
 mono/mono#16 0x00000000004200db in mono_main_with_options (argv=0x7ffc7324ef68, argc=10) at main.c:45
 mono/mono#17 main (argc=10, argv=0x7ffc7324ef68) at main.c:338

 =================================================================
 Got a SIGABRT while executing native code. This usually indicates
 a fatal error in the mono runtime or one of the native libraries
 used by your application.
 =================================================================
```

Commit migrated from mono/mono@98a369f
picenka21 pushed a commit to picenka21/runtime that referenced this pull request Feb 18, 2022
Reverts mono/mono@5e23a77

It seems to cause a crash during msbuild tests:

```
  xunit -> Microsoft.Build.Engine.UnitTests...
  Stacktrace:

  Native stacktrace:

  	0   mono                                0x0017cad4 mono_handle_native_crash + 308
  	1   mono                                0x001e2b03 sigabrt_signal_handler + 147
  	2   libsystem_platform.dylib            0x920a8deb _sigtramp + 43
  	3   ???                                 0xffffffff 0x0 + 4294967295
  	4   libsystem_c.dylib                   0x940bb27c abort + 155
  	5   mono                                0x0036886d mono_log_write_logfile + 381
  	6   mono                                0x003630d2 structured_log_adapter + 50
  	7   mono                                0x00380d1b monoeg_assertion_message + 107
  	8   mono                                0x0033863d major_scan_object_with_evacuation + 3373
  	9   mono                                0x0033b3d0 drain_gray_stack + 6608
  	10  mono                                0x0032df57 finish_gray_stack + 151
  	11  mono                                0x0032d3c6 major_finish_collection + 118
  	12  mono                                0x00329909 major_do_collection + 169
  	13  mono                                0x003288bd sgen_perform_collection + 605
  	14  mono                                0x0032a90b sgen_gc_collect + 75
  	15  mono                                0x002d5c4d unload_thread_main + 861
  	16  mono                                0x002abb6b start_wrapper + 795
  	17  libsystem_pthread.dylib             0x9ae6d5fb _pthread_body + 144
  	18  libsystem_pthread.dylib             0x9ae6d485 _pthread_struct_init + 0
  	19  libsystem_pthread.dylib             0x9ae72cf2 thread_start + 34

  Debug info from gdb:

  (lldb) command source -s 0 '/tmp/mono-gdb-commands.2tso9f'
  Executing commands in '/tmp/mono-gdb-commands.2tso9f'.
  (lldb) process attach --pid 2037
  2017-06-02 13:07:23.000 lldb[2093:282f] Metadata.framework [Error]: couldn't get the client port
  Process 2037 stopped
  * thread mono/mono#1, name = 'tid_507', queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
      frame mono/mono#0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
  libsystem_kernel.dylib`__psynch_cvwait:
  ->  0x923cc7ca <+10>: jae    0x923cc7da                ; <+26>
      0x923cc7cc <+12>: calll  0x923cc7d1                ; <+17>
      0x923cc7d1 <+17>: popl   %edx
      0x923cc7d2 <+18>: movl   0xe0b084f(%edx), %edx

  Executable module set to "/Users/builder/data/lanes/2716/mono-mac-sdk/external/bockbuild/stage/bin/mono".
  Architecture set to: i386-apple-macosx.
  (lldb) thread list
  Process 2037 stopped
  * thread mono/mono#1: tid = 0x530e96a, 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'tid_507', queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
    thread mono/mono#2: tid = 0x530e96b, 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
    thread mono/mono#3: tid = 0x530e96c, 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'SGen worker'
    thread mono/mono#4: tid = 0x530e96d, 0x923c7fb6 libsystem_kernel.dylib`semaphore_wait_trap + 10, name = 'Finalizer'
    thread mono/mono#5: tid = 0x530e96e, 0x923cd992 libsystem_kernel.dylib`kevent64 + 10, queue = 'com.apple.libdispatch-manager'
    thread mono/mono#6: tid = 0x530ea26, 0x923ccace libsystem_kernel.dylib`__select + 10, name = 'tid_5a03'
    thread mono/mono#7: tid = 0x530edf1, 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'tid_4007'
    thread mono/mono#8: tid = 0x530edf2, 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'Threadpool worker'
    thread mono/mono#9: tid = 0x530edf3, 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'Threadpool worker'
    thread mono/mono#10: tid = 0x530edf4, 0x923ccff2 libsystem_kernel.dylib`__wait4 + 10, name = 'Domain unloader'
  (lldb) thread backtrace all
  * thread mono/mono#1, name = 'tid_507', queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
    * frame mono/mono#0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
      frame mono/mono#1: 0x9ae6fd1d libsystem_pthread.dylib`_pthread_cond_wait + 728
      frame mono/mono#2: 0x9ae71bd9 libsystem_pthread.dylib`pthread_cond_wait$UNIX2003 + 71
      frame mono/mono#3: 0x00361ea9 mono`mono_os_event_wait_multiple + 505
      frame mono/mono#4: 0x00361ca5 mono`mono_os_event_wait_one + 53
      frame mono/mono#5: 0x00376b49 mono`mono_thread_info_wait_one_handle + 41
      frame mono/mono#6: 0x002d51b5 mono`mono_domain_try_unload + 485
      frame mono/mono#7: 0x002d4f6a mono`ves_icall_System_AppDomain_InternalUnload + 90
      frame mono/mono#8: 0x05bf9ee0
      frame mono/mono#9: 0x018ce01d mscorlib.dll.dylib`System_AppDomain_Unload_System_AppDomain + 45
      frame mono/mono#10: 0x05bf9d60
      frame mono/mono#11: 0x05bf9ccc
      frame mono/mono#12: 0x05bf9d04
      frame mono/mono#13: 0x05bf9c90
      frame mono/mono#14: 0x05bf996d
      frame mono/mono#15: 0x02e7d171
      frame mono/mono#16: 0x005c26d4
      frame mono/mono#17: 0x005b6878
      frame mono/mono#18: 0x005b6b7a
      frame mono/mono#19: 0x000c38a8 mono`mono_jit_runtime_invoke + 1592
      frame mono/mono#20: 0x002e43fe mono`do_runtime_invoke + 94
      frame mono/mono#21: 0x002e7de3 mono`do_exec_main_checked + 147
      frame mono/mono#22: 0x002e69a5 mono`mono_runtime_run_main_checked + 69
      frame mono/mono#23: 0x0013b687 mono`mono_jit_exec + 311
      frame mono/mono#24: 0x0013e2b2 mono`mono_main + 10114
      frame mono/mono#25: 0x000b22db mono`main + 2011
      frame mono/mono#26: 0x000b1af5 mono`start + 53
    thread mono/mono#2, name = 'SGen worker'
      frame mono/mono#0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
      frame mono/mono#1: 0x9ae6fd1d libsystem_pthread.dylib`_pthread_cond_wait + 728
      frame mono/mono#2: 0x9ae71bd9 libsystem_pthread.dylib`pthread_cond_wait$UNIX2003 + 71
      frame mono/mono#3: 0x0035f0e9 mono`thread_func + 249
      frame mono/mono#4: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame mono/mono#5: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame mono/mono#6: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread mono/mono#3, name = 'SGen worker'
      frame mono/mono#0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
      frame mono/mono#1: 0x9ae6fd1d libsystem_pthread.dylib`_pthread_cond_wait + 728
      frame mono/mono#2: 0x9ae71bd9 libsystem_pthread.dylib`pthread_cond_wait$UNIX2003 + 71
      frame mono/mono#3: 0x0035f0e9 mono`thread_func + 249
      frame mono/mono#4: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame mono/mono#5: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame mono/mono#6: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread mono/mono#4, name = 'Finalizer'
      frame mono/mono#0: 0x923c7fb6 libsystem_kernel.dylib`semaphore_wait_trap + 10
      frame mono/mono#1: 0x002dbeb6 mono`finalizer_thread + 278
      frame mono/mono#2: 0x002abb6b mono`start_wrapper + 795
      frame mono/mono#3: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame mono/mono#4: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame mono/mono#5: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread mono/mono#5, queue = 'com.apple.libdispatch-manager'
      frame mono/mono#0: 0x923cd992 libsystem_kernel.dylib`kevent64 + 10
      frame mono/mono#1: 0x91b5c899 libdispatch.dylib`_dispatch_mgr_invoke + 238
      frame mono/mono#2: 0x91b5c532 libdispatch.dylib`_dispatch_mgr_thread + 52
    thread mono/mono#6, name = 'tid_5a03'
      frame mono/mono#0: 0x923ccace libsystem_kernel.dylib`__select + 10
      frame mono/mono#1: 0x0036df29 mono`mono_poll + 409
      frame mono/mono#2: 0x002b482f mono`poll_event_wait + 111
      frame mono/mono#3: 0x002b345f mono`selector_thread + 1439
      frame mono/mono#4: 0x002abb6b mono`start_wrapper + 795
      frame mono/mono#5: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame mono/mono#6: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame mono/mono#7: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread mono/mono#7, name = 'tid_4007'
      frame mono/mono#0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
      frame mono/mono#1: 0x9ae6fd1d libsystem_pthread.dylib`_pthread_cond_wait + 728
      frame mono/mono#2: 0x9ae71c25 libsystem_pthread.dylib`pthread_cond_timedwait$UNIX2003 + 71
      frame mono/mono#3: 0x003760f3 mono`mono_thread_info_sleep + 979
      frame mono/mono#4: 0x002b1a86 mono`monitor_thread + 262
      frame mono/mono#5: 0x002abb6b mono`start_wrapper + 795
      frame mono/mono#6: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame mono/mono#7: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame mono/mono#8: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread mono/mono#8, name = 'Threadpool worker'
      frame mono/mono#0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
      frame mono/mono#1: 0x9ae6fd1d libsystem_pthread.dylib`_pthread_cond_wait + 728
      frame mono/mono#2: 0x9ae71c25 libsystem_pthread.dylib`pthread_cond_timedwait$UNIX2003 + 71
      frame mono/mono#3: 0x002b12e0 mono`worker_thread + 1024
      frame mono/mono#4: 0x002abb6b mono`start_wrapper + 795
      frame mono/mono#5: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame mono/mono#6: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame mono/mono#7: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread mono/mono#9, name = 'Threadpool worker'
      frame mono/mono#0: 0x923cc7ca libsystem_kernel.dylib`__psynch_cvwait + 10
      frame mono/mono#1: 0x9ae6fd1d libsystem_pthread.dylib`_pthread_cond_wait + 728
      frame mono/mono#2: 0x9ae71c25 libsystem_pthread.dylib`pthread_cond_timedwait$UNIX2003 + 71
      frame mono/mono#3: 0x002b12e0 mono`worker_thread + 1024
      frame mono/mono#4: 0x002abb6b mono`start_wrapper + 795
      frame mono/mono#5: 0x9ae6d5fb libsystem_pthread.dylib`_pthread_body + 144
      frame mono/mono#6: 0x9ae6d485 libsystem_pthread.dylib`_pthread_start + 130
      frame mono/mono#7: 0x9ae72cf2 libsystem_pthread.dylib`thread_start + 34
    thread mono/mono#10, name = 'Domain unloader'
      frame mono/mono#0: 0x923ccff2 libsystem_kernel.dylib`__wait4 + 10
      frame mono/mono#1: 0x940d9ea5 libsystem_c.dylib`waitpid$UNIX2003 + 48
      frame mono/mono#2: 0x0017cba7 mono`mono_handle_native_crash + 519
      frame mono/mono#3: 0x001e2b03 mono`sigabrt_signal_handler + 147
      frame mono/mono#4: 0x920a8deb libsystem_platform.dylib`_sigtramp + 43
  (lldb) detach
  Process 2037 detached
  (lldb) quit

  =================================================================
  Got a SIGABRT while executing native code. This usually indicates
  a fatal error in the mono runtime or one of the native libraries
  used by your application.
  =================================================================
```


Commit migrated from mono/mono@d30c17f
This pull request was closed.
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2 participants