[PyKDE] *very* strange thread error when calling python objects from within C

Patrick Stinson ajole-1 at gci.net
Tue Feb 10 10:36:01 GMT 2004


On Monday 09 February 2004 17:24, Patrick Stinson wrote:
> On Sunday 08 February 2004 02:26, Phil Thompson wrote:
> > On Sunday 08 February 2004 9:15 am, Patrick Stinson wrote:
> > > Actually, I'm not sure what the error really is related to, but I'll
> > > try to explain it. I have a C++ library that stores 'Module' objects
> > > internally. background thread loops forever and calls 'Produce()' and
> > > 'Consume()' in that order on the module objects. The problem is that
> > > only recently, that background thread seems to lock itself *and* the
> > > parent thread when it calls a Produce() or Consume() on an object that
> > > was created in python. Execution never enters the method in question,
> > > and the parent thread never returns from a 'time.sleep(2)' python call
> > > (which is really freaking me out, btw). Everything works fine if the
> > > module object is created from within the C++ code, or if that calling
> > > loop is executed from the main thread. I've tried starting the thread
> > > from python (using 'thread.start_new_thread()'), and from the C++
> > > library, using pthreads directly. My C++ 'Module' class declares
> > > Consume() and Produce as public and virtual void, the subclass defines
> > > them as public and void, and the respective definitions in the sip
> > > files reflect this exactly (had problems with that stuff before, very
> > > frustrating). Sorry that was so long, but I think this problem will
> > > require thourough explanation.
> >
> > I'm not clear - are you wrapping your own C++ thread creation class?
> >
> > If so, have you specified the /NewThread/ tag to the start method - see
> > qthread.sip. Ignore the /CreatesThread/ tag - that's for SIP v3.
> >
> > Phil
>
> Umm, yes, well actually no. I've wrapped access the Engine class (static
> within my C++ namespace) for simple access, but that object is really a
> global object in my C++ namespace, and the namespace has a GetEngine() for
> it.
>
> More:
> My 'Sample : Module' class was completely written in C++, but wrapped in
> python by sip. The C++ class adds itself to the C++ library code that calls
> Produce() and Consume() on that sample in another thread. If I have the C++
> library create it's own Sample object, thereby avoiding python code
> altogether, everything works fine. Also, if I run the method that contains
> the 'background thread' code from the main thread instead of a new thread
> (like thread.start_new_thread and pthread_create), everything is fine.
>
> _______________________________________________
> PyKDE mailing list    PyKDE at mats.imk.fraunhofer.de
> http://mats.imk.fraunhofer.de/mailman/listinfo/pykde


I rolled back to sip3.8 (from above version) to try out the lib, and it fixed 
the problem. Suppose this would end up being an interesting bug for the 
log...




More information about the PyQt mailing list