On Tue, Jul 8, 2008 at 6:11 AM, Turnaev Eugeny <turnaev at t72.ru> wrote: > > Hi. > > I have found why my program was deadlocking. > > in py_pjsua.c > > in function > static PyObject *py_pjsua_handle_events(PyObject *pSelf, > PyObject *pArgs) > > I have commented > lines Py_BEGIN_ALLOW_THREADS > and Py_END_ALLOW_THREADS > > those are python macro witch allow other python threads to run > while current thread is in some long running IO aperations for > example. > > Thanks for the info. Frankly I've forgotten why those macros are there, but reading the code comments there I'm not too sure if removing it is a good idea. According to the comments, and if I recall correctly, without those macros the readline() call (used by pjsua_app.py to operate console menu) will block forever. So are you sure that's a good idea? If so then probably we can also remove PyGILState_Ensure()/PyGILState_Release() call in ENTER_PYTHON()/LEAVE_PYTHON() macros. One thing for sure, I was unsure about which threading model works best when I created py_pjsua.c, and I experimented with several threading models. So it could be that some of these are artifacts from that experimentations. > Also i get rid of worker_thread to poll with handle_events() .. now > i am > polling from the thread where all other calls to py_pjsua lib is > located. > > That would be the best way indeed. But now that you invoke pjsua from one thread, the original handle_events() (with Py_BEGIN_ALLOW_THREADS) should work, shouldn't it? > Maybe the deadlocking situation was like this: > > a worker thread called hanle_events > inside handle events .. some pjsua internal > functions > is called to get events.. mutexes acquired. > > now a context switches.. ( because we have other python > threads and Py_BEGIN_ALLOW_THREADS was called) > > context switched to other python thread calling another > py_pjsua func.. > so another pjsua internal function is entered.. > > This must not be a problem as long as mutexes acuried in the > same order.. > and in FAQ it is stated that in pjsip acquires mutexes in > one order.. > Yep, normally that shouldn't be a problem, assuming that application doesn't have it's own mutex. Of course in this case the application, i.e. Python, does have a mutex, so this what might have caused the problem (probably because Py_BEGIN_ALLOW_THREADS releases Python mutex?). > > I dont know i think i saw 2 different macro.. in pjsua .. a > try_to_get_mutex > and get_mutex.. maybe problem in this. > > That's just for deadlock detection, shouldn't be a problem. > > > Ok. i am not stating pjsua have a deadlock bug, maybe this was my > bad > application design or i messed up somewhere else. > But my app design a little bit mimics design of app in example > > http://svn.pjsip.org/repos/pjproject/trunk/pjsip-apps/src/py_pjsua/pjsua_app.py > 1 worker thread.. and also calls from other thread.. > So i assume that example also have a deadlock problem.. > it is just a metter of load.. achitecture gived in example worked > for me > if i had 1 simul call.. and when i started with 16 simul calls it is > deadlocked > in about 1-5 minutes.. (and as i can see from debug it is deadlocked > in a call to py_pjsua) > Yeah, could be. I'm now also working on the wrapper again so I'll look into that. > > Btw in example - another thread (main in example and not main in my > app) is not registered > with py_pjsua.thread_register() .. so what threads examply must be > registed > i am not getting it. > Sorry I don't get you. But the main thread doesn't need to be register, since calling pj_init() will implicitly registers the thread. > > Now i have no worker thread... i am polling right from the thread > where all other > calls to pj_pjsua located and also removed Py_BEGIN_ALLOW_THREADS > from handle_events > to disallow interleave of threads while i am in handle_events(). > > Try putting sleep() in the other thread (the one that doesn't call pjsua), and see if that thread block forever. ;-) > > So anyone working from python with pjsua can do the same if having > unexpected problems with deadlocks :) > > Best wishes for developers of pjsua, nice work :) > > Thanks. I'm now working on object oriented Python wrapper on top of the C Python module, hopefully that will make it easier to use. Stay tuned! :) Cheers Benny -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20080708/fb6e3dff/attachment-0001.html
