x/mobile: App crashed on startup.

[C-ollins]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go version go1.10.3 linux/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

linux amd64

What did you do?

Crashes on second run of the app, doesn't crash at first. It crashes at launch every 2 intervals.

If possible, provide a recipe for reproducing the error.
All you need is to run the app.
Source Code

What did you expect to see?

A successful launch

What did you see instead?

Crashed app
Log output:

06-22 09:57:41.166 19102-0/com.dcrandroid E/Go: runtime: writebarrierptr *0x93a31398 = 0x6ce
    fatal error: bad pointer in write barrier
06-22 09:57:41.174 19102-0/com.dcrandroid E/Go: runtime stack:
    runtime.throw(0x934411d5, 0x1c)
    	/usr/local/go/src/runtime/panic.go:616 +0x64
06-22 09:57:41.175 19102-0/com.dcrandroid E/Go: runtime.writebarrierptr.func1()
    	/usr/local/go/src/runtime/mbarrier.go:215 +0x94
    runtime.systemstack(0xbeca810c)
    	/usr/local/go/src/runtime/asm_arm.s:349 +0x8c
    runtime.mstart()
    	/usr/local/go/src/runtime/proc.go:1175
    goroutine 17 [running, locked to thread]:
    runtime.systemstack_switch()
    	/usr/local/go/src/runtime/asm_arm.s:294 +0x4 fp=0x4f94af38 sp=0x4f94af34 pc=0x930fb5e4
    runtime.writebarrierptr(0x93a31398, 0x6ce)
    	/usr/local/go/src/runtime/mbarrier.go:213 +0x84 fp=0x4f94af50 sp=0x4f94af38 pc=0x930b3930
    golang.org/x/mobile/internal/mobileinit.SetCurrentContext(...)
    	/home/collins/go/src/golang.org/x/mobile/internal/mobileinit/ctx_android.go:83
    golang.org/x/mobile/bind/java.setContext(...)
    	/home/collins/go/src/golang.org/x/mobile/bind/java/context_android.go:20
    golang.org/x/mobile/bind/java._cgoexpwrap_720489891265_setContext(0xaccf6000, 0x6ce)
06-22 09:57:41.176 19102-0/com.dcrandroid E/Go: 	_cgo_gotypes.go:66 +0x78 fp=0x4f94af60 sp=0x4f94af50 pc=0x93416260
    runtime.call16(0x0, 0xbeca8130, 0xbeca81c4, 0x8, 0x0)
    	/usr/local/go/src/runtime/asm_arm.s:518 +0x4c fp=0x4f94af74 sp=0x4f94af60 pc=0x930fba48
    runtime.cgocallbackg1(0x0)
    	/usr/local/go/src/runtime/cgocall.go:316 +0x150 fp=0x4f94afb4 sp=0x4f94af74 pc=0x930a3c0c
    runtime.cgocallbackg(0x0)
    	/usr/local/go/src/runtime/cgocall.go:194 +0xa4 fp=0x4f94afe4 sp=0x4f94afb4 pc=0x930a3a40
    runtime.cgocallback_gofunc(0x0, 0x0, 0x0, 0x4f94c000)
    	/usr/local/go/src/runtime/asm_arm.s:720 +0x7c fp=0x4f94aff0 sp=0x4f94afe4 pc=0x930fd368
    runtime.goexit()
    	/usr/local/go/src/runtime/asm_arm.s:1015 +0x4 fp=0x4f94aff0 sp=0x4f94aff0 pc=0x930fd664
    goroutine 5 [runnable]:
    syscall.Syscall(0x3, 0x27, 0x4f9aa000, 0x400, 0x57, 0x0, 0x0)
    	/usr/local/go/src/syscall/asm_linux_arm.s:17 +0x8
    syscall.read(0x27, 0x4f9aa000, 0x400, 0x400, 0xffffff01, 0x0, 0x0)
    	/usr/local/go/src/syscall/zsyscall_linux_arm.go:749 +0x44
    syscall.Read(0x27, 0x4f9aa000, 0x400, 0x400, 0xffffffff, 0x93835b40, 0x939eca14)
    	/usr/local/go/src/syscall/syscall_unix.go:162 +0x34
06-22 09:57:41.177 19102-0/com.dcrandroid E/Go: internal/poll.(*FD).Read(0x4f96a100, 0x4f9aa000, 0x400, 0x400, 0x0, 0x0, 0x0)
    	/usr/local/go/src/internal/poll/fd_unix.go:153 +0xf0
    os.(*File).read(0x4f92a170, 0x4f9aa000, 0x400, 0x400, 0x0, 0x930b22c8, 0x930b2bf8)
    	/usr/local/go/src/os/file_unix.go:226 +0x3c
    os.(*File).Read(0x4f92a170, 0x4f9aa000, 0x400, 0x400, 0x1, 0x0, 0x0)
    	/usr/local/go/src/os/file.go:107 +0x4c
    bufio.(*Reader).fill(0x4f939fb8)
    	/usr/local/go/src/bufio/bufio.go:100 +0x104
    bufio.(*Reader).ReadSlice(0x4f939fb8, 0x92ea960a, 0x0, 0x0, 0x0, 0x0, 0x0)
    	/usr/local/go/src/bufio/bufio.go:341 +0x1c
    bufio.(*Reader).ReadLine(0x4f939fb8, 0x400, 0x400, 0x4f9aa000, 0x400, 0x400, 0x0)
    	/usr/local/go/src/bufio/bufio.go:370 +0x24
    golang.org/x/mobile/internal/mobileinit.lineLog(0x4f92a170, 0x6)
    	/home/collins/go/src/golang.org/x/mobile/internal/mobileinit/mobileinit_android.go:55 +0x98
    created by golang.org/x/mobile/internal/mobileinit.init.0
    	/home/collins/go/src/golang.org/x/mobile/internal/mobileinit/mobileinit_android.go:82 +0x10c
    goroutine 6 [IO wait]:
06-22 09:57:41.178 19102-0/com.dcrandroid E/Go: internal/poll.runtime_pollWait(0x92972e80, 0x72, 0x4f9aa400)
    	/usr/local/go/src/runtime/netpoll.go:173 +0x44
    internal/poll.(*pollDesc).wait(0x4f96a194, 0x72, 0xffffff01, 0x93835b40, 0x939eca14)
    	/usr/local/go/src/internal/poll/fd_poll_runtime.go:85 +0xa0
    internal/poll.(*pollDesc).waitRead(0x4f96a194, 0x4f9aa401, 0x400, 0x400)
    	/usr/local/go/src/internal/poll/fd_poll_runtime.go:90 +0x2c
    internal/poll.(*FD).Read(0x4f96a180, 0x4f9aa400, 0x400, 0x400, 0x0, 0x0, 0x0)
    	/usr/local/go/src/internal/poll/fd_unix.go:157 +0x150
    os.(*File).read(0x4f92a180, 0x4f9aa400, 0x400, 0x400, 0x0, 0x0, 0x0)
    	/usr/local/go/src/os/file_unix.go:226 +0x3c
    os.(*File).Read(0x4f92a180, 0x4f9aa400, 0x400, 0x400, 0x0, 0x0, 0x0)
    	/usr/local/go/src/os/file.go:107 +0x4c
    bufio.(*Reader).fill(0x4f93a7b8)
    	/usr/local/go/src/bufio/bufio.go:100 +0x104
    bufio.(*Reader).ReadSlice(0x4f93a7b8, 0x92ea960a, 0x0, 0x0, 0x0, 0x0, 0x0)
    	/usr/local/go/src/bufio/bufio.go:341 +0x1c
06-22 09:57:41.179 19102-0/com.dcrandroid E/Go: bufio.(*Reader).ReadLine(0x4f93a7b8, 0x400, 0x400, 0x4f9aa400, 0x400, 0x400, 0x0)
    	/usr/local/go/src/bufio/bufio.go:370 +0x24
    golang.org/x/mobile/internal/mobileinit.lineLog(0x4f92a180, 0x4)
    	/home/collins/go/src/golang.org/x/mobile/internal/mobileinit/mobileinit_android.go:55 +0x98
    created by golang.org/x/mobile/internal/mobileinit.init.0
    	/home/collins/go/src/golang.org/x/mobile/internal/mobileinit/mobileinit_android.go:92 +0x1c8
    goroutine 22 [syscall]:
    os/signal.signal_recv(0x0)
    	/usr/local/go/src/runtime/sigqueue.go:139 +0x14c
    os/signal.loop()
    	/usr/local/go/src/os/signal/signal_unix.go:22 +0x14
    created by os/signal.init.0
    	/usr/local/go/src/os/signal/signal_unix.go:28 +0x34
    goroutine 23 [select, locked to thread]:
    runtime.gopark(0x93833b64, 0x0, 0x934359f8, 0x6, 0x18, 0x1)
    	/usr/local/go/src/runtime/proc.go:291 +0x10c
06-22 09:57:41.180 19102-0/com.dcrandroid E/Go: runtime.selectgo(0x4f9367a0, 0x4fda2100)
    	/usr/local/go/src/runtime/select.go:392 +0xee4
    runtime.ensureSigM.func1()
    	/usr/local/go/src/runtime/signal_unix.go:549 +0x1e0
    runtime.goexit()
    	/usr/local/go/src/runtime/asm_arm.s:1015 +0x4
    
    --------- beginning of crash
06-22 09:57:41.183 19102-19102/com.dcrandroid A/libc: Fatal signal 6 (SIGABRT), code -6 in tid 19102 (com.dcrandroid)

[ianlancetaylor]

This kind of error normally means that you have a non-pointer value that you have converted to a pointer type, probably when making a call out of Go. In Go, variables of pointer type must always hold pointer values.

[C-ollins]

Everything shown in the stacktrace is not from my code. Everything is from gomobile. I don't have any null pointer in my code and nothing passes null, the worst from is an empty string, never null.

[agnivade]

@steeve @hyangah

@C-ollins - Could you also try with 1.13beta1 and the latest from the gomobile repo just so we ensure that this is not something already fixed ? Thanks.

[steeve]

This was fixed in Go 1.12. It was due to Android's jvalue being declared as void* but not being pointers. Go now detects it and there is a test.

Internally we have the same test should it break again somehow.

[C-ollins]

@agnivade I’ve worked on the project for a while now and the error doesn’t occur anymore

[agnivade]

Thanks, I will close it then. Please try with the latest released version if it happens again in the future.