[libvirt] 'make check' hangs

[Daniel P. Berrange]

On Wed, Nov 30, 2011 at 11:48:16AM +0100, Jiri Denemark wrote:
> On Wed, Nov 30, 2011 at 09:01:28 +0000, Daniel P. Berrange wrote:
> > On Wed, Nov 30, 2011 at 11:18:23AM +0800, Wen Congyang wrote:
> > > When I run 'make check', it hangs sometimes.
> > > 
> > > I use gdb to attach lt-virsh, and the following is the
> > > backtrace:
> > > (gdb) thread 1
> > > [Switching to thread 1 (Thread 0x7fc6c04d5800 (LWP 24099))]#0  0x0000003bdce0804d in pthread_join () from /lib64/libpthread.so.0
> > > (gdb) bt
> > > #0  0x0000003bdce0804d in pthread_join () from /lib64/libpthread.so.0
> > > #1  0x000000000041c0b3 in vshDeinit (ctl=0x7fff015f4570) at virsh.c:17262
> > > #2  0x00000000004248d1 in main (argc=<value optimized out>, argv=0x7fff015f4728) at virsh.c:17608
> > > (gdb) thread 2
> > > [Switching to thread 2 (Thread 0x7fc6c04d4700 (LWP 24138))]#0  0x0000003bdc2dc053 in poll () from /lib64/libc.so.6
> > > (gdb) bt
> > > #0  0x0000003bdc2dc053 in poll () from /lib64/libc.so.6
> > > #1  0x00007fc6c075359c in virEventPollRunOnce () at util/event_poll.c:619
> > > #2  0x00007fc6c07527d7 in virEventRunDefaultImpl () at util/event.c:247
> > > #3  0x000000000041bea3 in vshEventLoop (opaque=0x7fff015f4570) at virsh.c:16800
> > > #4  0x00007fc6c0764702 in virThreadHelper (data=<value optimized out>) at util/threads-pthread.c:157
> > > #5  0x0000003bdce077f1 in start_thread () from /lib64/libpthread.so.0
> > > #6  0x0000003bdc2e570d in clone () from /lib64/libc.so.6
> > > (gdb) 
> > 
> > 
> > I've seen this once, for the first time yesterday, but I can't
> > see any obvious change in either virsh, or the event code that
> > would have caused this to start happening in the past couple
> > of days.
> 
> Hmm, I suspect this may be caused by
> 
> commit fd7e85ac6af833845aa0eb2526158c319800a0ae
> Author: Jiri Denemark <jdenemar at redhat.com>
> Date:   Tue Oct 11 15:05:52 2011 +0200
> 
>     virsh: Always run event loop
> 
>     Since virsh already implements event loop, it has to also run it. So far
>     the event loop was only running during virsh console command.
> 
> However, the commit added a special hack to prevent this from happening:
> 
>     @@ -17080,6 +17101,16 @@ vshDeinit(vshControl *ctl)
>          }
>          virResetLastError();
> 
>     +    if (ctl->eventLoopStarted) {
>     +        /* HACK: Add a dummy timeout to break event loop */
>     +        int timer = virEventAddTimeout(-1, NULL, NULL, NULL);
>     +        if (timer != -1)
>     +            virEventRemoveTimeout(timer);
>     +
>     +        virThreadJoin(&ctl->eventLoop);
>     +        ctl->eventLoopStarted = false;
>     +    }
>     +
>          return true;
>      }
> 
> Perhaps it's not working as expected.

Ahhh, I had discounted that because the date was Oct 11, and I figured
we would have seen it by now. But that's just your original commit date,
the merge date was Oct 24th. So yeah, I reckon this must be the culprit


Daniel
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