[gst-devel] Threads in 0.8.10

[MDK]

Uh. I've got serious problems understanding how threading works in
0.8.10... I've got the following pipeline:


+Thread_1-------------+     +Thread_2---------------------+
|                     |     |                             |
|                     |     | +Queue------+ +AlsaSink--+  |
|                [asrc] --- | [sink]  [src]-[sink]     |  |
|                     |     | +-----------+ +----------+  |
|                     |     +-----------------------------+
| (Avi file bin with  |
|  a loopfunc that    |     +Thread_3---------------------+
|  pushes on asrc &   |     |                             |
|  vsrc)              |     | +Queue------+ +XvImagesink+ |
|                [vsrc] --- | [sink]  [src]-[sink]      | |
|                     |     | +-----------+ +-----------+ |
+---------------------+     +-----------------------------+

Now, I already smoked 2 packs of ciggarettes today trying to figure out
what's the right way to stop/start this pipeline. 

When I "play", I change the state of Thread_1 to PLAYING and wait till
on of the queues fills up (overrun). Than I start playing Thread_2 and
Thread_3. That works pretty smoothly. 

The problem is with pausing. I think I tried every possible combination 
here...

---

01:	gst_set_element_state (Thread_3, GST_STATE_PAUSED)
02:	gst_set_element_state (Thread_2, GST_STATE_PAUSED)
03:	gst_set_element_state (Thread_1, GST_STATE_PAUSED)

I lock on 03 as Thread_1 is locked in a push on the queue that's already
full. I tried pausing Thread_1 from the Overrun func, but It seems it
doesn't work (not suprising)

---

01:	gst_set_element_state (Thread_1, GST_STATE_PAUSED)
02:	gst_set_element_state (Thread_2, GST_STATE_PAUSED)
03:	gst_set_element_state (Thread_3, GST_STATE_PAUSED)

That works 90% of times. But in the remaining 10% it locks on 02 (or 03)
supposingly because of underrun (?). 

...
gstelement.c(2825):gst_element_set_state_func:<thread2> setting state
from PLAYING to PAUSED 
(LOCK)
...

I tried messing up with queue params (may-deadlock, block-timeout) but
it doesn't help :

ERROR (0x82cf468 - 311246:07:25.740349000)  queue_dataflow(11011)
gstqueue.c(821):gst_queue_get:<queue2> deadlock found, shutting down
sink pad elements
INFO  (0x82cf468 - 311246:07:25.740381000) GST_ERROR_SYSTEM(11011)
gstelement.c(2606):gst_element_error_full: signaling error in queue2:
Internal GStreamer error: thread problem.  File a bug.
INFO  (0x82cf468 - 311246:07:25.740438000) GST_ERROR_SYSTEM(11011)
gstelement.c(2634):gst_element_error_full: signalled error in queue2:
Internal GStreamer error: thread problem.  File a bug.

I also tried inserting my own mutexes and doing other nasty things. I'm
lost. 

Should the threads call the state_change functions from within
themselves or is it okay to call them from the outside world? (Thread_4
in this example, the "GUI" thread)


-- 
Michał Dominik K.
mdk at mdk.org.pl
www.mdk.org.pl