pthread_join() problem

David Stacey
Fri Jun 7 20:07:00 GMT 2013

On 07/06/13 16:58, Christopher Faylor wrote:
> On Mon, Jun 03, 2013 at 12:01:02PM +0200, Corinna Vinschen wrote:
>> >On Jun  2 23:01, David Stacey wrote:
>>> >>I'm trying to get Poco[1] working under Cygwin, and have hit a
>>> >>problem with the way it manages its threads. A short example
>>> >>(attached) shows what's going on.
>>> >>
>>> >>Poco creates a global object that is used for managing various
>>> >>threads. In the destructor, the class calls pthread_join() to wait
>>> >>for the threads to finish. This works in Fedora (and presumably
>>> >>other Linux variants), but under Cygwin this call never returns.
>>> >>Note that the object is global, and so pthread_join() is being
>>> >>called after main() has returned and the global variables are being
>>> >>mopped up.
>>> >>
>>> >>In the attached example, the problem only exists if the
>>> >>'thread_container' object is global. When run in this way,
>>> >>pthread_join() never returns and the programme locks up. If
>>> >>'thread_container' is moved local to main() then the programme works
>>> >>correctly. Sadly, I can't make such a trivial fix to the Poco code,
>>> >>which rather relies on this object being global.
>>> >>
>>> >>The attached example (and indeed Poco) runs fine under Fedora 18
>>> >>x64, but locks up on Cygwin (32-bit; haven't tried 64-bit). Problem
>>> >>exists with a vanilla cygwin-1.7.18-1 and the most recent snapshot
>>> >>(2013-06-02).
>> >
>> >Thanks for the simple testcase!
>> >
>> >I tracked this down to a problem in the process exit handling which
>> >disallowed pthreads to exit when process exit was in progress (and
>> >running the global destructors is part of the process exit).  I fixed
>> >that in CVS.
>> >
>> >I'm just uploading a 2013-06-03 snapshot to
>> >as well as generating a 1.7.9-10 cygwin package for the 64 bit test
>> >distro.  Please give either one of them a try, especially with poco.
> I've reworked this change since Corinna's fix was to what should have
> been obsolete code.  A new snapshot should be uploaded soon.
> Could you confirm that things still work as expected?

Thank you for looking at this problem and for providing a new snapshot. 
I have tested the 2013-06-07 snapshot, and can confirm that both my 
testcase and Poco threads function correctly.

Many thanks once again,


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