[Mono-list] CPU hang after mod-mono-server shutdown

Felix Berlakovich felix at berlakovich.at
Fri Sep 23 07:49:29 UTC 2016


Hi!

Yes in Debian it seems to be mono-dbg and mono-runtime-dbg. In installed both, along with several debug symbols for libraries.

Felix

Von: Jo Shields [mailto:joshield at microsoft.com]
Gesendet: Freitag, 23. September 2016 02:03
An: Alexander Köplinger
Cc: Felix Berlakovich; mono-list at lists.dot.net
Betreff: Re: [Mono-list] CPU hang after mod-mono-server shutdown

mono-runtime-dbg iirc

Sent from my iPhone

On 23 Sep 2016, at 00:52, Alexander Köplinger <alkpli at microsoft.com<mailto:alkpli at microsoft.com>> wrote:
For the managed assemblies the symbols package for debian is called "mono-dbg" (you need to run mono with the --debug flag).

@Jo do we have something similar for the runtime as well?

- Alex

From: Mono-list <mono-list-bounces at lists.dot.net<mailto:mono-list-bounces at lists.dot.net>> on behalf of Rodrigo Kumpera <kumpera at gmail.com<mailto:kumpera at gmail.com>>
Date: Friday 23 September 2016 at 00:12
To: Felix Berlakovich <felix at berlakovich.at<mailto:felix at berlakovich.at>>
Cc: "mono-list at lists.dot.net<mailto:mono-list at lists.dot.net>" <mono-list at lists.dot.net<mailto:mono-list at lists.dot.net>>
Subject: Re: [Mono-list] CPU hang after mod-mono-server shutdown

Hey Felix,

You should install the debug symbols from your distro as there's nothing we can say from an incomplete backtrace.

--
Rodrigo

On Thu, Sep 22, 2016 at 2:18 AM, Felix Berlakovich <felix at berlakovich.at<mailto:felix at berlakovich.at>> wrote:
Hi!

I have a problem with a ASP.NET<http://ASP.NET> ServiceStack (3.9.72) application and mod-mono-server. I am running the application on Debian 8.5 with Apache 2.4.10 and mono 4.6 with Debian packages from mono-project.com<http://mono-project.com>. Everything works as expected except for a shutdown of the mod-mono-server. The shutdown occurs either on apache restart, apache stop or mod-mono-server -terminate. My application is shutdown properly (Application_End is executed), but then the mono process goes into a CPU loop. In case of apache restart a new process is spawned afterwards, but the hanging process remains. The hanging process can only be killed with kill -9.

My observations so far:

*         The hang does not occur with nginx + hyperfastcgi, so it cannot be a general problem with my application. I would strongly prefer apache though.

*         The hang does not occur with the mono ASP.NET<http://ASP.NET> example application

*         The hang occurs only after my application was loaded by mod-mono-server, i.e. at least one request to the application is needed before the shutdown

*         mod-mono-server logs a "mod-mono-server received a shutdown message" message before the hang

I have traced a shutdown of mod-mono-server and attached the tail of the log at [1]. Furthermore I attached to the hanging process with gdb and issued a thread apply all bt. The output is attached at [2]. I am completely out of ideas on how to further troubleshoot this problem.

Regards

Felix

[1] tail of a traced mod-mono-server shutdown:

[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
85      ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S: Datei oder Verzeichnis nicht gefunden.
  Id   Target Id         Frame
  10   Thread 0x7f76d6fff700 (LWP 17622) "SGen worker" pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
  9    Thread 0x7f76d4fd2700 (LWP 17623) "Finalizer" sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
  8    Thread 0x7f76cffff700 (LWP 17625) "Main" 0x00007f76d83bdaed in poll () at ../sysdeps/unix/syscall-template.S:81
  7    Thread 0x7f76cffbe700 (LWP 17626) "Main" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  6    Thread 0x7f76cff7d700 (LWP 17627) "Threadpool work" 0x00007f76d83afbb7 in sched_yield () at ../sysdeps/unix/syscall-template.S:81
  5    Thread 0x7f76cfd7c700 (LWP 17628) "Threadpool work" 0x00007f76d88ae4c9 in __libc_waitpid (pid=17645, stat_loc=0x7f76d91f411c, options=0) at ../sysdeps/unix/sysv/linux/waitpid.c:40
  4    Thread 0x7f76cfb7b700 (LWP 17629) "Threadpool work" 0x00007f76d83b9bbd in read () at ../sysdeps/unix/syscall-template.S:81
  3    Thread 0x7f76ce6fb700 (LWP 17633) "Timer-Scheduler" pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
  2    Thread 0x7f76d423f700 (LWP 17644) "Threadpool work" 0x00007f76d83afbb7 in sched_yield () at ../sysdeps/unix/syscall-template.S:81
* 1    Thread 0x7f76d93d8740 (LWP 17621) "Main" sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85

Thread 10 (Thread 0x7f76d6fff700 (LWP 17622)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x0000000000623dc7 in ?? ()
#2  0x00007f76d88a70a4 in start_thread (arg=0x7f76d6fff700) at pthread_create.c:309
#3  0x00007f76d83c662d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 9 (Thread 0x7f76d4fd2700 (LWP 17623)):
#0  sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
#1  0x00000000005bbc99 in ?? ()
#2  0x000000000059c87c in ?? ()
#3  0x0000000000653eec in ?? ()
#4  0x00007f76d88a70a4 in start_thread (arg=0x7f76d4fd2700) at pthread_create.c:309
#5  0x00007f76d83c662d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 8 (Thread 0x7f76cffff700 (LWP 17625)):
#0  0x00007f76d83bdaed in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00000000005a2d8f in ?? ()
#2  0x00000000005a3da3 in ?? ()
#3  0x000000000059c87c in ?? ()
#4  0x0000000000653eec in ?? ()
#5  0x00007f76d88a70a4 in start_thread (arg=0x7f76cffff700) at pthread_create.c:309
#6  0x00007f76d83c662d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 7 (Thread 0x7f76cffbe700 (LWP 17626)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
#1  0x0000000000652375 in ?? ()
#2  0x00000000005a12e8 in ?? ()
#3  0x000000000059c87c in ?? ()
#4  0x0000000000653eec in ?? ()
#5  0x00007f76d88a70a4 in start_thread (arg=0x7f76cffbe700) at pthread_create.c:309
#6  0x00007f76d83c662d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 6 (Thread 0x7f76cff7d700 (LWP 17627)):
#0  0x00007f76d83afbb7 in sched_yield () at ../sysdeps/unix/syscall-template.S:81
#1  0x0000000000653dd9 in ?? ()
#2  0x0000000000479f05 in ?? ()
#3  0x000000004067e4ac in ?? ()
#4  0x00007f76ce7abe98 in ?? ()
#5  0x00007f76cff7c6e8 in ?? ()
#6  0x0000000000000031 in ?? ()
#7  0x00007f76cff7c6e0 in ?? ()
#8  0x0000000000000031 in ?? ()
#9  0x00007f76cff7c6c0 in ?? ()
#10 0x0000000000000000 in ?? ()

Thread 5 (Thread 0x7f76cfd7c700 (LWP 17628)):
#0  0x00007f76d88ae4c9 in __libc_waitpid (pid=17645, stat_loc=0x7f76d91f411c, options=0) at ../sysdeps/unix/sysv/linux/waitpid.c:40
#1  0x00000000004acd59 in ?? ()
#2  0x00000000005040fe in ?? ()
#3  0x00000000004275d7 in ?? ()
#4  <signal handler called>
#5  0x000000000047a2b8 in ?? ()
#6  0x0000000040cb8984 in ?? ()
#7  0x00007f76cdce92b0 in ?? ()
#8  0x0000000002c294a0 in ?? ()
#9  0x0000000000000000 in ?? ()

Thread 4 (Thread 0x7f76cfb7b700 (LWP 17629)):
#0  0x00007f76d83b9bbd in read () at ../sysdeps/unix/syscall-template.S:81
#1  0x0000000040692807 in ?? ()
#2  0x00007f76d73246f8 in ?? ()
#3  0x00007f76b8001950 in ?? ()
#4  0x00007f76d7324688 in ?? ()
#5  0x00007f76cfb7a780 in ?? ()
#6  0x00007f76cfb7a730 in ?? ()
#7  0x00007f76d73246f8 in ?? ()
#8  0x00007f76d7324688 in ?? ()
#9  0x00007f76d7325a48 in ?? ()
#10 0x0000000000000020 in ?? ()
#11 0x00007f76d7324610 in ?? ()
#12 0x00007f76cfb7a820 in ?? ()
#13 0x000000004069259c in ?? ()
#14 0x00000000000000ff in ?? ()
#15 0xffffffffffffffff in ?? ()
#16 0xe000fa03dd00fa03 in ?? ()
#17 0x0000000000000000 in ?? ()

Thread 3 (Thread 0x7f76ce6fb700 (LWP 17633)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:238
#1  0x000000000062a1c8 in ?? ()
#2  0x000000000063fedd in ?? ()
#3  0x000000000059c5b7 in ?? ()
#4  0x000000000059d876 in ?? ()
#5  0x000000004070d1ec in ?? ()
#6  0x00007f76d70eafa8 in ?? ()
#7  0x00007f76ac001950 in ?? ()
#8  0x00007f76d70eafa8 in ?? ()
#9  0x00007f76ce6fa540 in ?? ()
#10 0x00007f76ce6fa4f0 in ?? ()
#11 0x0000000000000001 in ?? ()
#12 0x00007f76d70eafa8 in ?? ()
#13 0x00007f76d70eaf70 in ?? ()
#14 0x00000000000003e6 in ?? ()
#15 0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7f76d423f700 (LWP 17644)):
#0  0x00007f76d83afbb7 in sched_yield () at ../sysdeps/unix/syscall-template.S:81
#1  0x0000000000653dd9 in ?? ()
#2  0x0000000000479f05 in ?? ()
#3  0x000000004058ef64 in ?? ()
#4  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f76d93d8740 (LWP 17621)):
#0  sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
#1  0x0000000000650e50 in ?? ()
#2  0x0000000000599e1d in ?? ()
#3  0x000000000059ea63 in mono_thread_manage ()
#4  0x000000000047eb52 in mono_main ()
#5  0x0000000000422258 in ?? ()
#6  0x00007f76d82ffb45 in __libc_start_main (main=0x422160, argc=9, argv=0x7ffd524d96c8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffd524d96b8) at libc-start.c:287
#7  0x0000000000422651 in _start ()

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

[0x7f76cfd7c700: 9,79980 14] ENTER: (wrapper delegate-invoke) <Module>:invoke_void_object_EventArgs (object,System.EventArgs)(this:0x7f76cdce92b0[System.EventHandler a005241e],


[2] gdb thread apply all bt in the hanging mono process

Thread 5 (Thread 0x7fa95d7ff700 (LWP 17716)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x0000000000623dc7 in ?? ()
#2  0x00007fa95ecfa0a4 in start_thread (arg=0x7fa95d7ff700) at pthread_create.c:309
#3  0x00007fa95e81962d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 4 (Thread 0x7fa95b434700 (LWP 17771)):
#0  sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
#1  0x00000000005bbc99 in ?? ()
#2  0x000000000059c87c in ?? ()
#3  0x0000000000653eec in ?? ()
#4  0x00007fa95ecfa0a4 in start_thread (arg=0x7fa95b434700) at pthread_create.c:309
#5  0x00007fa95e81962d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 3 (Thread 0x7fa95a1f3700 (LWP 17783)):
#0  sem_timedwait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_timedwait.S:101
#1  0x0000000000651868 in ?? ()
#2  0x0000000000652b14 in ?? ()
#3  0x0000000000598fac in ?? ()
#4  0x000000000059b93e in ?? ()
#5  0x0000000000546146 in ?? ()
#6  0x0000000042501901 in ?? ()
#7  0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7fa931cff700 (LWP 17795)):
#0  0x00007fa95e7663e2 in do_sigsuspend (set=0x98c340) at ../sysdeps/unix/sysv/linux/sigsuspend.c:31
#1  __GI___sigsuspend (set=0x98c340) at ../sysdeps/unix/sysv/linux/sigsuspend.c:45
#2  0x00000000006543de in ?? ()
#3  <signal handler called>
#4  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#5  0x000000000062a2e1 in ?? ()
#6  0x0000000000640044 in ?? ()
#7  0x00000000005a1f3b in ?? ()
#8  0x00000000005b597f in ?? ()
#9  0x0000000000653eec in ?? ()
#10 0x00007fa95ecfa0a4 in start_thread (arg=0x7fa931cff700) at pthread_create.c:309
#11 0x00007fa95e81962d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 1 (Thread 0x7fa95f82b740 (LWP 17711)):
#0  sem_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S:85
#1  0x0000000000650e50 in ?? ()
#2  0x0000000000599e1d in ?? ()
#3  0x000000000059ea63 in mono_thread_manage ()
#4  0x000000000047eb52 in mono_main ()
#5  0x0000000000422258 in ?? ()
#6  0x00007fa95e752b45 in __libc_start_main (main=0x422160, argc=9, argv=0x7ffccf689c28, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffccf689c18) at libc-start.c:287
#7  0x0000000000422651 in _start ()

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