Possible thread sync error in proton/qpid-cpp

[Chris Richardson <cr...@fourc.eu>]

Hi,

As per the subject I'm experiencing a crash which I am _reeaasonably_ sure
I've pinpointed to a problem with one of the C/C++ Qpid client libraries.
Of course I could also be doing something goofy in which case I apologise
profusely!

The problem manifests in a number of different ways including a double-free
and stack trace, an error message (when built in debug) reading
proton-c/src/object/object.c:236: pn_object_decref: Assertion
`head->refcount > 0' failed.
and a simple segfault with no further info. I've examined some core dumps
which give some further hints about the problem but I won't include results
here - instead I've tried to distil the problem down to the attached
source. Two things seem to be key - using AMQP1.0 (0-10 is fine) and
creating and closing sessions very fast while sending some message over the
link. I realise this may not be typical usage but it does happen in my
integration testing and causes my tests to crash!

The versions I've tested with are:
qpid-proton-0.9.1-rc1 / qpid-cpp-0-34
qpid-proton-0.14.0 / qpid-cpp-1.35

Compiler: gcc (Ubuntu 5.4.0-6ubuntu1~16.04.2) 5.4.0 20160609

I've been testing against c++ broker 0.34 and 1.35 fairly indiscriminately
on the assumption it's not really relevant to the crash.

Sample code - build with eg:
g++ -g -std=c++11 -o qpid-test main.cxx  /usr/local/lib/libqpidmessaging.so
/usr/local/lib/libqpidtypes.so

Regards

-- 

*Chris Richardson*, System Architect
cr@fourc.eu


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Re: Possible thread sync error in proton/qpid-cpp

[Gordon Sim <gs...@redhat.com>]

On 02/11/16 19:38, Chris Richardson wrote:
> As per the subject I'm experiencing a crash which I am _reeaasonably_
> sure I've pinpointed to a problem with one of the C/C++ Qpid client
> libraries.

I've checked in a couple of fixes that address the issues:

https://issues.apache.org/jira/browse/QPID-7500
https://issues.apache.org/jira/browse/QPID-7501

Thanks again for reporting the issue and for the reproducer!

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Re: Possible thread sync error in proton/qpid-cpp

[Gordon Sim <gs...@redhat.com>]

On 02/11/16 19:38, Chris Richardson wrote:
> Hi,
>
> As per the subject I'm experiencing a crash which I am _reeaasonably_
> sure I've pinpointed to a problem with one of the C/C++ Qpid client
> libraries. Of course I could also be doing something goofy in which case
> I apologise profusely!

No, it is indeed a bug, thanks for the reproducer! I'll have a think 
about how best to fix it.



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