Crash in NSURLConnectionLoader

[kkaefer]

Just encountered this crash while running test cases. The crash occured while running OnlineFileSource.Load:

It's a little bit worrying that there's no Mapbox GL code in there; this seems to be internal to the framework. However, it could also point to us misusing it:

com.apple.NSURLConnectionLoader (11)
#0  0x0000000100816e49 in __gcd_queue_item_enqueue_hook_block_invoke ()
#1  0x0000000100816477 in gcd_queue_item_enqueue_hook ()
#2  0x00000001008504e4 in _dispatch_introspection_queue_item_enqueue_hook ()
#3  0x000000010083a699 in _dispatch_queue_push ()
#4  0x00007fffc97db5f2 in HSTSStorage::copyHSTSInfoDictionary(__CFString const*) ()
#5  0x00007fffc969cce2 in HSTSPolicy::isKnownHSTSHost(unsigned char*, long) const ()
#6  0x00007fffc9775438 in HSTSPolicy::isKnownHSTSHost(__CFURL const*) const ()
#7  0x00007fffc98ba12b in StrictSecurityPolicy::strictSecurityPolicyInEffectForURL(__CFURL const*, __CFDictionary const*) ()
#8  0x00007fffc9892446 in HTTPProtocol::loadConformsToStrictSecurityPolicy() ()
#9  0x00007fffc96a60d4 in HTTPProtocol::_protocolInterface_startLoad(_CFCachedURLResponse const*) ()
#10 0x00007fffc969ea4a in ___ZN19URLConnectionLoader27_private_ScheduleOriginLoadEPK12NSURLRequestPK20_CFCachedURLResponse_block_invoke_2 ()
#11 0x00007fffc969e9d9 in ___ZNK19URLConnectionLoader25withExistingProtocolAsyncEU13block_pointerFvP11URLProtocolE_block_invoke ()
#12 0x0000000100823fcc in _dispatch_client_callout ()
#13 0x0000000100839b04 in _dispatch_block_invoke_direct ()
#14 0x00007fffc969d8d0 in RunloopBlockContext::_invoke_block(void const*, void*) ()
#15 0x00007fffca468bf4 in CFArrayApplyFunction ()
#16 0x00007fffc969d7c9 in RunloopBlockContext::perform() ()
#17 0x00007fffc969d660 in MultiplexerSource::perform() ()
#18 0x00007fffc969d482 in MultiplexerSource::_perform(void*) ()
#19 0x00007fffca4c4581 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ ()
#20 0x00007fffca4a598c in __CFRunLoopDoSources0 ()
#21 0x00007fffca4a4e76 in __CFRunLoopRun ()
#22 0x00007fffca4a4874 in CFRunLoopRunSpecific ()
#23 0x00007fffc9679144 in +[NSURLConnection(Loader) _resourceLoadLoop:] ()
#24 0x00007fffcbed130d in __NSThread__start__ ()
#25 0x000000010089bc60 in _pthread_body ()
#26 0x000000010089bbac in _pthread_start ()
#27 0x000000010089b3bd in thread_start ()

[kkaefer]

Just triggered this again.

[kkaefer]

Got it again. I should add that in all cases, Xcode crashed shortly after reporting this error.

[1ec5]

Did you encounter this crash on iOS or macOS?

[kkaefer]

macOS

[1ec5]

What specific version of macOS are you running? Is this macosapp or a test application (and is it sandboxed)? Do you know what URL we were trying to fetch when the crash occurred?

[kkaefer]

Got another one on master:

Queue : com.apple.main-thread (serial)
#0  0x0000000101c2ee49 in __gcd_queue_item_enqueue_hook_block_invoke ()
#1  0x0000000101c2e477 in gcd_queue_item_enqueue_hook ()
#2  0x0000000101c684e4 in _dispatch_introspection_queue_item_enqueue_hook ()
#3  0x0000000101c52699 in _dispatch_queue_push ()
#4  0x00007fffcea88972 in -[__NSCFURLSessionTask resume] ()
#5  0x00000001004eeccc in mbgl::HTTPFileSource::request(mbgl::Resource const&, std::__1::function<void (mbgl::Response)>) at platform/darwin/src/http_file_source.mm:331
#6  0x0000000100575964 in mbgl::OnlineFileSource::Impl::activateRequest(mbgl::OnlineFileRequest*) at platform/default/online_file_source.cpp:103
#7  0x00000001005733b0 in mbgl::OnlineFileSource::Impl::activatePendingRequest() at platform/default/online_file_source.cpp:122
#8  0x0000000100577f07 in mbgl::OnlineFileSource::Impl::activateRequest(mbgl::OnlineFileRequest*)::'lambda'(mbgl::Response)::operator()(mbgl::Response) const at platform/default/online_file_source.cpp:105
#9  0x0000000100577e5b in decltype(std::__1::forward<mbgl::OnlineFileSource::Impl::activateRequest(mbgl::OnlineFileRequest*)::'lambda'(mbgl::Response)&>(fp)(std::__1::forward<mbgl::Response>(fp0))) std::__1::__invoke<mbgl::OnlineFileSource::Impl::activateRequest(mbgl::OnlineFileRequest*)::'lambda'(mbgl::Response)&, mbgl::Response>(mbgl::OnlineFileSource::Impl::activateRequest(mbgl::OnlineFileRequest*)::'lambda'(mbgl::Response)&&&, mbgl::Response&&) [inlined] at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/__functional_base:416
#10 0x0000000100577e0a in void std::__1::__invoke_void_return_wrapper<void>::__call<mbgl::OnlineFileSource::Impl::activateRequest(mbgl::OnlineFileRequest*)::'lambda'(mbgl::Response)&, mbgl::Response>(mbgl::OnlineFileSource::Impl::activateRequest(mbgl::OnlineFileRequest*)::'lambda'(mbgl::Response)&&&, mbgl::Response&&) at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/__functional_base:468
#11 0x0000000100577d19 in std::__1::__function::__func<mbgl::OnlineFileSource::Impl::activateRequest(mbgl::OnlineFileRequest*)::'lambda'(mbgl::Response), std::__1::allocator<mbgl::OnlineFileSource::Impl::activateRequest(mbgl::OnlineFileRequest*)::'lambda'(mbgl::Response)>, void (mbgl::Response)>::operator()(mbgl::Response&&) at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/functional:1437
#12 0x00000001000dbec1 in std::__1::function<void (mbgl::Response)>::operator()(mbgl::Response) const at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/functional:1817
#13 0x00000001004f7c3f in _ZNK4mbgl11HTTPRequest5asyncMUlvE_clEv at platform/darwin/src/http_file_source.mm:77
#14 0x00000001004f7b9d in _ZNSt3__18__invokeIRN4mbgl11HTTPRequest5asyncMUlvE_EJEEEDTclclsr3std3__1E7forwardIT_Efp_Espclsr3std3__1E7forwardIT0_Efp0_EEEOS5_DpOS6_ [inlined] at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/__functional_base:416
#15 0x00000001004f7b8c in _ZNSt3__128__invoke_void_return_wrapperIvE6__callIJRN4mbgl11HTTPRequest5asyncMUlvE_EEEEvDpOT_ at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/__functional_base:468
#16 0x00000001004f7ab9 in _ZNSt3__110__function6__funcIN4mbgl11HTTPRequest5asyncMUlvE_ENS_9allocatorIS4_EEFvvEEclEv at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/functional:1437
#17 0x0000000100123fae in std::__1::function<void ()>::operator()() const at /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/functional:1817
#18 0x0000000100b18a3e in mbgl::util::AsyncTask::Impl::runTask() at platform/darwin/src/async_task.cpp:45
#19 0x0000000100b189a5 in mbgl::util::AsyncTask::Impl::perform(void*) at platform/darwin/src/async_task.cpp:50
#20 0x00007fffcf8cc581 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ ()
#21 0x00007fffcf8ad98c in __CFRunLoopDoSources0 ()
#22 0x00007fffcf8ace76 in __CFRunLoopRun ()
#23 0x00007fffcf8ac874 in CFRunLoopRunSpecific ()
#24 0x00007fffcf8ebdc1 in CFRunLoopRun ()
#25 0x0000000100b1a0c1 in mbgl::util::RunLoop::run() at platform/darwin/src/run_loop.cpp:39
#26 0x000000010026be52 in OnlineFileSource_Load_Test::TestBody() at test/storage/online_file_source.test.cpp:258
#27 0x0000000100b100f3 in void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) ()
#28 0x0000000100afb027 in void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) ()
#29 0x0000000100acac95 in testing::Test::Run() ()
#30 0x0000000100acc1db in testing::TestInfo::Run() ()
#31 0x0000000100acce77 in testing::TestCase::Run() ()
#32 0x0000000100adb653 in testing::internal::UnitTestImpl::RunAllTests() ()
#33 0x0000000100b13fb3 in bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) ()
#34 0x0000000100afd707 in bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) ()
#35 0x0000000100adb250 in testing::UnitTest::Run() ()
#36 0x0000000100166b21 in RUN_ALL_TESTS() at mason_packages/osx-x86_64/gtest/1.7.0/include/gtest/gtest.h:20058
#37 0x0000000100166906 in mbgl::runTests(int, char**) at test/src/mbgl/test/test.cpp:14
#38 0x00000001001576af in main at test/src/main.cpp:19
#39 0x00007fffe497e255 in start ()

[mheins57]

I've been getting these occasionally on iOS 10.0.2 (14A456), so it's not unique to OS X:

#0  0x000000010139ae8c in __gcd_queue_item_enqueue_hook_block_invoke ()
#1  0x000000010139a41c in gcd_queue_item_enqueue_hook ()
#2  0x00000001019d9ee8 in _dispatch_introspection_queue_item_enqueue_hook ()
#3  0x00000001019b8ba4 in _dispatch_queue_push ()
#4  0x000000018a07dac0 in URLConnectionInstanceData::withWorkQueueAsync(void () block_pointer) const ()
#5  0x000000018a08eb9c in URLConnectionLoader_Classic::protocolDidLoadData(__CFData const*, long long) ()
#6  0x000000018a0487f0 in HTTPProtocol::tryToSendDispatchDataToDelegate(dispatch_data_s*) ()
#7  0x000000018a04252c in HTTPProtocol::bytesAvailable(dispatch_data_s*) ()
#8  0x000000018a041b5c in HTTPProtocol::handleStreamEvent(__CFHTTPMessage*, dispatch_data_s*, CFStreamError const*) ()
#9  0x000000018a120d48 in ___ZN15HTTPTransaction22_onqueue_invokeHandlerEv_block_invoke.64 ()
#10 0x00000001019ad21c in _dispatch_client_callout ()
#11 0x00000001019b7c9c in _dispatch_block_invoke_direct ()
#12 0x000000018a13ae98 in RunloopBlockContext::_invoke_block(void const*, void*) ()
#13 0x00000001897f99a8 in CFArrayApplyFunction ()
#14 0x000000018a13ad7c in RunloopBlockContext::perform() ()
#15 0x000000018a13c0a4 in MultiplexerSource::perform() ()
#16 0x000000018a13be10 in MultiplexerSource::_perform(void*) ()
#17 0x00000001898ce278 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ ()
#18 0x00000001898cdbc0 in __CFRunLoopDoSources0 ()
#19 0x00000001898cb7c0 in __CFRunLoopRun ()
#20 0x00000001897fa048 in CFRunLoopRunSpecific ()
#21 0x0000000189fe7cec in +[NSURLConnection(Loader) _resourceLoadLoop:] ()
#22 0x000000018a40650c in __NSThread__start__ ()
#23 0x00000001889b3860 in _pthread_body ()
#24 0x00000001889b3770 in _pthread_start ()
#25 0x00000001889b0dbc in thread_start ()

[wibge]

I get this consistently on the ios 10.1 simulator when downloading a multi-thousand tile region.

* thread #27: tid = 0x24bbd06, 0x0000000107623eac libBacktraceRecording.dylib`__gcd_queue_item_enqueue_hook_block_invoke + 4, queue = 'com.apple.NSURLSession-work', stop reason = EXC_BAD_ACCESS (code=1, address=0x36)
  * frame #0: 0x0000000107623eac libBacktraceRecording.dylib`__gcd_queue_item_enqueue_hook_block_invoke + 4
    frame #1: 0x000000010762351d libBacktraceRecording.dylib`gcd_queue_item_enqueue_hook + 241
    frame #2: 0x000000010edace47 libdispatch.dylib`_dispatch_introspection_queue_item_enqueue_hook + 46
    frame #3: 0x000000010ed866a0 libdispatch.dylib`_dispatch_queue_push + 313
    frame #4: 0x0000000107a864ff CFNetwork`-[__NSCFURLSessionConnection withWorkQueueAsync:] + 79
    frame #5: 0x0000000107a9153d CFNetwork`SessionConnectionLoadable::withLoaderClientAsync(void (LoaderClientInterface*) block_pointer) + 99
    frame #6: 0x0000000107aa0d02 CFNetwork`URLConnectionLoader::protocolDidFinishLoading() + 608
    frame #7: 0x0000000107a8b45d CFNetwork`___ZNK25URLConnectionInstanceData18withWorkQueueAsyncEU13block_pointerFvvE_block_invoke + 16
    frame #8: 0x000000010ed81980 libdispatch.dylib`_dispatch_call_block_and_release + 12
    frame #9: 0x000000010edab0cd libdispatch.dylib`_dispatch_client_callout + 8
    frame #10: 0x000000010ed88e6b libdispatch.dylib`_dispatch_queue_serial_drain + 236
    frame #11: 0x000000010ed89b9f libdispatch.dylib`_dispatch_queue_invoke + 1073
    frame #12: 0x000000010ed8c3b7 libdispatch.dylib`_dispatch_root_queue_drain + 720
    frame #13: 0x000000010ed8c08b libdispatch.dylib`_dispatch_worker_thread3 + 123
    frame #14: 0x000000010f1544de libsystem_pthread.dylib`_pthread_wqthread + 1129
    frame #15: 0x000000010f152341 libsystem_pthread.dylib`start_wqthread + 13

[jfirebaugh]

http://stackoverflow.com/a/40536997/52207

After speaking with Apple Technical Support we confirmed that it's a bug within the libBacktraceRecording.dylib library, which is used for debugging within Xcode. I have filed a bug report and have been told that it won't crash on a users device since this is a debug error that occurs within a library not present on most users' devices.