Hello
I believe I came across an issue that causes a soft deadlock between
pjsua_get_call_info and ios_stream_stop when hanging up a video call
and grabbing the call information in the on_call_state callback. At
least on my machines this is very reproducible as it happens 9 times
out of 10.
PJSIP is compiled with FFMPEG and x264. When ending a call, the code
in pjsua_call.c pjsua_call_on_state_changed() triggers which at one
point calls the on_call_state callback.
Afterwards, in the same file, it PJSUA_LOCK()s the mutex and calls
pjsua_media_channel_deinit(). A couple of levels deep this finally
gets to the ios_stream_stop() function which attempts to switch to the
main thread so it can end the AVCaptureSession:
if ([NSThread isMainThread]) {
[stream->cap_session stopRunning];
} else {
dispatch_sync(dispatch_get_main_queue(), ^{ [stream->cap_session
stopRunning]; }); }
Now, if the callback code passes that message on using a dispatch_* or
another method and executes moments later and attempts to get the call
information, pjsua_call_get_info() will attempt to PJSUA_LOCK() as
well, which will fail and start waiting for the mutex to unlock. At
the same time, the ios_stream_stop() dispatch_sync tries to execute,
but because of the pending pjsua_call_get_info() mutex it never
actually gets a chance to and therefore the mutex initially locked by
pjsua_media_channel_deinit() is never unlocked.
To make matters worse, I also have a periodical pjsua_call_get_info()
call that triggers every second on the main thread, so that probably
helps with making the issue more reproducible.
I'm trying to find a solution for this that doesn't involve moving the
pjsua_call_get_info() to a whole new thread, but so far I've come
short. Can anyone offer me a suggestion?
Thanks
