Thanks Rafael - finally got this raised with source code attached - see 
https://issues.apache.org/jira/browse/PROTON-346


-----Original Message-----
From: Rafael Schloming [mailto:r...@alum.mit.edu]
Sent: Monday, June 24, 2013 9:43 AM
To: proton@qpid.apache.org
Cc: Damian Maguire; Glenn McClements
Subject: Re: Deadlock in pn_messenger_stop? (C Qpid Library)

Go ahead and raise a ticket for it and attach the reproducer. I'm currently
banging my head against another bug, but I'll take a look as soon as my
head or the other bug gives way. ;-)

--Rafael


On Sat, Jun 22, 2013 at 7:09 AM, Frank Quinn <fqu...@nyx.com> wrote:

> Hi folks,
>
> Can you confirm that this is an issue? Should I raise a ticket for this?
>
> Cheers,
> Frank
>
> ----- Original Message -----
> From: Frank Quinn
> Sent: Friday, June 14, 2013 06:03 PM
> To: 'proton@qpid.apache.org' <proton@qpid.apache.org>
> Cc: Damian Maguire; Glenn McClements
> Subject: RE: Deadlock in pn_messenger_stop? (C Qpid Library)
>
> Hmm - perhaps I spoke too soon...
>
> This looked like it worked in that little test application but when I
> plugged it into my actual application, it seemed to work some of the times
> and not others. I then took your advice and introduced a join in the test
> application and as soon as I do so, stopping the subscriber on the
> subscriber thread stopped working (perhaps it never did work properly and
> this just flagged it).
>
> I have attached the latest source for it with the subscriber living
> entirely on its own thread, and with a join now introduced in main(). It
> deadlocks with the same backtrace as originally reported when trying to run
> pn_messenger_stop.
>
> Cheers,
> Frank
>
> -----Original Message-----
> From: Frank Quinn
> Sent: 14 June 2013 13:49
> To: proton@qpid.apache.org
> Subject: RE: Deadlock in pn_messenger_stop? (C Qpid Library)
>
> Thanks Ted,
>
> I did try inserting a sleep of 1s between the send and the stop (I
> suspected the same thing you did), but the behaviour persisted so I don't
> think the problem was the time for the message to land.
>
> However, your suggestion to stop it in the subscriber thread did seem to
> work (still unsure why, but I'll not question it for now), thanks!
>
> Cheers,
> Frank
>
> -----Original Message-----
> From: Ted Ross [mailto:tr...@redhat.com]
> Sent: 14 June 2013 13:09
> To: proton@qpid.apache.org
> Subject: Re: Deadlock in pn_messenger_stop? (C Qpid Library)
>
> I would suggest that you not stop the subscriber messenger in the main
> thread.  Rather, stop it in the subscriber thread right before it exits.
>  Alternatively (preferably), you should pthread_join the thread in main
> before stopping the messengers.
>
> It looks to me that you've got a race condition where main is stopping
> mSub at the same time the thread is processing messages on mSub.
>
> Keep in mind that pn_messenger_send is only going to block until the
> message has been pushed to the socket.  It will not wait for the message to
> be received and processed by the other thread.
>
> -Ted
>
>
> On 06/14/2013 07:10 AM, Frank Quinn wrote:
> > Hi Folks,
> >
> > See attached code: I'm encountering a deadlock when I try to stop
> > messengers. The general workflow is:
> >
> > 1. Create pub and sub Messengers
> > 2. Start the Messengers
> > 3. Thread sub off onto its own thread as recv is a blocking call 4.
> > Publish round trip from the pub messenger to the sub messenger with a
> > destroy subject (recv is uninteruptable at the moment so this is our
> > only to interrupt it) 5. Stop the messengers
> >
> > When I try and stop the messengers, the application deadlocks with the
> > following backtrace (there is only one thread running at this point as
> > the subscribe thread has since exited):
> >
> > Thread 1 (Thread 0x7f38181a4840 (LWP 6688)):
> > #0  0x0000003518ce99ad in poll () at
> > ../sysdeps/unix/syscall-template.S:81
> > #1  0x000000309c226a1c in poll (__timeout=<optimized out>,
> > __nfds=<optimized out>, __fds=<optimized out>)
> >     at /usr/include/bits/poll2.h:46
> > #2  pn_driver_wait_2 (d=d@entry=0x1a81140, timeout=<optimized out>,
> > timeout@entry=-1)
> >     at /usr/src/debug/qpid-proton-0.4/proton-c/src/posix/driver.c:752
> > #3  0x000000309c226c42 in pn_driver_wait (d=0x1a81140,
> > timeout=timeout@entry=-1)
> >     at /usr/src/debug/qpid-proton-0.4/proton-c/src/posix/driver.c:807
> > #4  0x000000309c2242d3 in pn_messenger_tsync (messenger=0x1a81050,
> >     predicate=0x309c222d80 <pn_messenger_stopped>, timeout=<optimized
> > out>)
> >     at /usr/src/debug/qpid-proton-0.4/proton-c/src/messenger.c:623
> > #5  0x0000000000400ffb in main () at qpid_deadlock_repro.c:123
> >
> > Is this the correct workflow for this or am I missing a flush or
> > unlock step somewhere along the way?
> >
> > Cheers,
> > Frank
> >
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