[Mono-dev] Shutdown hangs

Mon Jul 18 21:48:59 UTC 2016

Does Xamarin (or anyone else) offer paid support for server-side mono issues like this? The support offerings on their website only mention mobile apps.

chris

-----Original Message-----
From: Chris Swiedler 
Sent: Tuesday, July 12, 2016 9:19 AM
To: 'Chris Swiedler' <cswiedler at trionworlds.com>; mono-devel-list <mono-devel-list at lists.ximian.com>
Subject: RE: Shutdown hangs

Switching to mono 4.0.5 seems a little better, but the problem (or a similar problem) is still there, and I get segfaults and other problems with 4.0.

Does anyone have any suggestions for brute-force ways to fix this problem? E.g., can I modify ves_icall_System_Environment_Exit or similar to just call exit()? I haven't looked at the code but from the call stacks it seems like this happens in an attempt to make an orderly shutdown of threads. While that would be nice, it's much more important to me for the application to actually exit. If I have to, I'll make the process kill itself with SIGKILL, but I'd rather not since then I lose the actual exit code.

chris

-----Original Message-----
From: mono-devel-list-bounces at lists.ximian.com [mailto:mono-devel-list-bounces at lists.ximian.com] On Behalf Of Chris Swiedler
Sent: Monday, June 13, 2016 9:55 AM
To: mono-devel-list <mono-devel-list at lists.ximian.com>
Subject: [Mono-dev] Shutdown hangs

I'm getting semi-reliable shutdown hangs in a mono command-line app using mono 4.2.3 on Centos 7 64-bit. The app does different things at different times, and the shutdowns only seem to happen when it connects to our SQL server database (using the Mono database bindings, not ODBC). We've also seen an occasional segfault, also seemingly only when doing database work, though those may have gone away since upgrading to 4.2.3.

Does anyone have any thoughts? Pstack output below.

Thanks,
chris

Thread 5 (Thread 0x7f4c777ff700 (LWP 11658)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00000000005f786c in thread_func (thread_data=0x0) at sgen-thread-pool.c:118
#2  0x00007f4c77ffedf5 in start_thread (arg=0x7f4c777ff700) at pthread_create.c:308
#3  0x00007f4c77d2c1ad in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 4 (Thread 0x7f4c75560700 (LWP 11659)):
#0  sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
#1  0x000000000061aa37 in mono_sem_wait (sem=sem at entry=0x953c40 <finalizer_sem>, alertable=alertable at entry=1) at mono-semaphore.c:107
#2  0x00000000005a1736 in finalizer_thread (unused=<optimized out>) at gc.c:1096
#3  0x00000000005841e9 in start_wrapper_internal (data=<optimized out>) at threads.c:725
#4  start_wrapper (data=<optimized out>) at threads.c:772
#5  0x0000000000621026 in inner_start_thread (arg=0x7fffda0d42e0) at mono-threads-posix.c:97
#6  0x00007f4c77ffedf5 in start_thread (arg=0x7f4c75560700) at pthread_create.c:308
#7  0x00007f4c77d2c1ad in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 3 (Thread 0x7f4c74fd3700 (LWP 11660)):
#0  sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
#1  0x000000000061aa37 in mono_sem_wait (sem=sem at entry=0x7f4c68000940, alertable=alertable at entry=0) at mono-semaphore.c:107
#2  0x000000000061f5ba in mono_thread_info_wait_for_resume (info=<optimized out>) at mono-threads.c:110
#3  mono_thread_info_end_self_suspend () at mono-threads.c:692
#4  0x0000000000583d2c in self_suspend_internal (thread=0x7f4c78a74330) at threads.c:4546
#5  mono_thread_execute_interruption (thread=thread at entry=0x7f4c78a74330) at threads.c:4050
#6  0x0000000000583f50 in mono_thread_interruption_checkpoint_request (bypass_abort_protection=bypass_abort_protection at entry=1) at threads.c:4184
#7  0x0000000000584dae in mono_thread_force_interruption_checkpoint () at threads.c:4221

Thread 2 (Thread 0x7f4c746ff700 (LWP 11661)):
#0  sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
#1  0x000000000061aa37 in mono_sem_wait (sem=sem at entry=0x7f4c6c000940, alertable=alertable at entry=0) at mono-semaphore.c:107
#2  0x000000000061f5ba in mono_thread_info_wait_for_resume (info=<optimized out>) at mono-threads.c:110
#3  mono_thread_info_end_self_suspend () at mono-threads.c:692
#4  0x0000000000583d2c in self_suspend_internal (thread=0x7f4c78a74430) at threads.c:4546
#5  mono_thread_execute_interruption (thread=thread at entry=0x7f4c78a74430) at threads.c:4050
#6  0x00000000005851f9 in ves_icall_System_Threading_Thread_Sleep_internal (ms=1000) at threads.c:1206
#17 0x00007f4c756fa2e7 in System_Threading_Thread_Sleep_int (millisecondsTimeout=1000) at /home/cswiedler/mono-main/Extern/mono/source/external/referencesource/mscorlib/system/threading/thread.cs:715

Thread 1 (Thread 0x7f4c78b34780 (LWP 11657)):
#0  0x00007f4c7800599d in nanosleep () at ../sysdeps/unix/syscall-template.S:81
#1  0x0000000000632a5a in monoeg_g_usleep (microseconds=1935890) at gdate-unix.c:53
#2  0x000000000061f2bb in suspend_sync_nolock (id=id at entry=139966347736832, interrupt_kernel=interrupt_kernel at entry=1) at mono-threads.c:870
#3  0x000000000061f732 in mono_thread_info_safe_suspend_and_run (id=139966347736832, interrupt_kernel=interrupt_kernel at entry=1, callback=callback at entry=0x5813c0 <suspend_thread_critical>, user_data=user_data at entry=0x7fffda0d3a10) at mono-threads.c:891
#4  0x0000000000581d29 in suspend_thread_internal (thread=0x7f4c78a74430, interrupt=1) at threads.c:4531
#5  0x00000000005834ff in mono_thread_suspend_all_other_threads () at threads.c:3154
#6  0x0000000000538176 in ves_icall_System_Environment_Exit (result=0) at icall.c:6006
#7  0x0000000040731832 in ?? ()
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