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Bug 707611 - rtspsrc state change always blocks when source is offline (waiting for connect timeout)
rtspsrc state change always blocks when source is offline (waiting for connec...
Status: RESOLVED FIXED
Product: GStreamer
Classification: Platform
Component: gst-plugins-base
git master
Other All
: Normal blocker
: 1.1.90
Assigned To: GStreamer Maintainers
GStreamer Maintainers
Depends on:
Blocks:
 
 
Reported: 2013-09-06 08:32 UTC by Dmitry Shatrov
Modified: 2013-09-18 16:51 UTC
See Also:
GNOME target: ---
GNOME version: ---


Description Dmitry Shatrov 2013-09-06 08:32:27 UTC 
gst_element_set_state (playbin, GST_STATE_PLAYING) always blocks for a pipeline with rtspsrc when source IP is not responding, i.e. it appears to wait synchronously for connect() to complete.

The problem appears to be because of the following lines in gstrtspsrc.c:

    case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
      /* unblock the tcp tasks and make the loop waiting */
      gst_rtspsrc_loop_send_cmd (rtspsrc, CMD_WAIT, CMD_LOOP);
      /* make sure it is waiting before we send PAUSE or PLAY below */
// BUG: BLOCKS HERE
      GST_RTSP_STREAM_LOCK (rtspsrc);
      GST_RTSP_STREAM_UNLOCK (rtspsrc);

Lock/unlock pair wasn't there in older versions, and gst_element_set_state() did not block (there was proper async state change).

Here are backtraces from my app for two threads. The first one is the application thread which should not block, but it blocks because of this bug. The second one is gstreamer's rtspsrc thread. Line numbers are for gstreamer-1.0.9 release.

Application thread:

+ Trace 232454

  • #0 __lll_lock_wait
    at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S line 135
  • #1 _L_lock_928
    from /opt/moment/lib/libpthread.so.0
  • #2 __GI___pthread_mutex_lock
    at pthread_mutex_lock.c line 85
  • #3 gst_rtspsrc_change_state
    at gstrtspsrc.c line 6725
  • #4 gst_element_change_state
    at gstelement.c line 2594
  • #5 gst_element_set_state_func
    at gstelement.c line 2550
  • #6 gst_bin_element_set_state
    at gstbin.c line 2292
  • #7 gst_bin_change_state_func
    at gstbin.c line 2594
  • #8 gst_uri_decode_bin_change_state
    at gsturidecodebin.c line 2580
  • #9 gst_element_change_state
    at gstelement.c line 2594
  • #10 gst_element_set_state_func
    at gstelement.c line 2550
  • #11 gst_bin_element_set_state
    at gstbin.c line 2292
  • #12 gst_bin_change_state_func
    at gstbin.c line 2594
  • #13 gst_pipeline_change_state
    at gstpipeline.c line 471
  • #14 gst_element_change_state
    at gstelement.c line 2594
  • #15 gst_element_set_state_func
    at gstelement.c line 2550
  • #0 poll
    at ../sysdeps/unix/syscall-template.S line 81
  • #1 g_socket_condition_timed_wait
    at gsocket.c line 3562
  • #2 do_connect
    at gstrtspconnection.c line 457
  • #3 gst_rtsp_connection_connect
    at gstrtspconnection.c line 725
  • #4 gst_rtsp_conninfo_connect
    at gstrtspsrc.c line 3371
  • #5 gst_rtspsrc_retrieve_sdp
    at gstrtspsrc.c line 5642
  • #6 gst_rtspsrc_open
    at gstrtspsrc.c line 5809
  • #7 gst_rtspsrc_thread
    at gstrtspsrc.c line 6602
  • #8 gst_task_func
    at gsttask.c line 316
  • #9 g_thread_pool_thread_proxy
    at gthreadpool.c line 309
  • #10 g_thread_proxy
    at gthread.c line 798
  • #11 start_thread
    at pthread_create.c line 308
  • #12 clone
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S line 114 






Comment 1


Dmitry Shatrov





          2013-09-06 08:34:06 UTC
        



Backtraces have been automatically screwed up by bugzilla. Repeating:

Application thread:




+
Trace
    232455






    

  • 
#0
__lll_lock_wait

    
                at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S
                  line
                  135

    

    • 

  • 
#1
_L_lock_928

    
                from
                /opt/moment/lib/libpthread.so.0

    

    • 

  • 
#2
__GI___pthread_mutex_lock

    
                at pthread_mutex_lock.c
                  line
                  85

    

    • 

  • 
#3
gst_rtspsrc_change_state

    
                at gstrtspsrc.c
                  line
                  6725

    

    • 

  • 
#4
gst_element_change_state

    
                at gstelement.c
                  line
                  2594

    

    • 

  • 
#5
gst_element_set_state_func

    
                at gstelement.c
                  line
                  2550

    

    • 

  • 
#6
gst_bin_element_set_state

    
                at gstbin.c
                  line
                  2292

    

    • 

  • 
#7
gst_bin_change_state_func

    
                at gstbin.c
                  line
                  2594

    

    • 

  • 
#8
gst_uri_decode_bin_change_state

    
                at gsturidecodebin.c
                  line
                  2580

    

    • 

  • 
#9
gst_element_change_state

    
                at gstelement.c
                  line
                  2594

    

    • 

  • 
#10
gst_element_set_state_func

    
                at gstelement.c
                  line
                  2550

    

    • 

  • 
#11
gst_bin_element_set_state

    
                at gstbin.c
                  line
                  2292

    

    • 

  • 
#12
gst_bin_change_state_func

    
                at gstbin.c
                  line
                  2594

    

    • 

  • 
#13
gst_pipeline_change_state

    
                at gstpipeline.c
                  line
                  471

    

    • 

  • 
#14
gst_element_change_state

    
                at gstelement.c
                  line
                  2594

    

    • 

  • 
#15
gst_element_set_state_func

    
                at gstelement.c
                  line
                  2550

    

    • 













Comment 2


Dmitry Shatrov





          2013-09-06 08:34:18 UTC
        



GStreamer rtspsrc thread:




+
Trace
    232456






    

  • 
#0
poll

    
                at ../sysdeps/unix/syscall-template.S
                  line
                  81

    

    • 

  • 
#1
g_socket_condition_timed_wait

    
                at gsocket.c
                  line
                  3562

    

    • 

  • 
#2
do_connect

    
                at gstrtspconnection.c
                  line
                  457

    

    • 

  • 
#3
gst_rtsp_connection_connect

    
                at gstrtspconnection.c
                  line
                  725

    

    • 

  • 
#4
gst_rtsp_conninfo_connect

    
                at gstrtspsrc.c
                  line
                  3371

    

    • 

  • 
#5
gst_rtspsrc_retrieve_sdp

    
                at gstrtspsrc.c
                  line
                  5642

    

    • 

  • 
#6
gst_rtspsrc_open

    
                at gstrtspsrc.c
                  line
                  5809

    

    • 

  • 
#7
gst_rtspsrc_thread

    
                at gstrtspsrc.c
                  line
                  6602

    

    • 

  • 
#8
gst_task_func

    
                at gsttask.c
                  line
                  316

    

    • 

  • 
#9
g_thread_pool_thread_proxy

    
                at gthreadpool.c
                  line
                  309

    

    • 

  • 
#10
g_thread_proxy

    
                at gthread.c
                  line
                  798

    

    • 

  • 
#11
start_thread

    
                at pthread_create.c
                  line
                  308

    

    • 

  • 
#12
clone

    
                at ../sysdeps/unix/sysv/linux/x86_64/clone.S
                  line
                  114

    

    • 













Comment 3


Dmitry Shatrov





          2013-09-06 08:49:32 UTC
        



Reverting gst-plugins-base commit b96d931bf4ce5c3c8c5be4fa76f5c75bca85d0c4 fixes the problem.






Comment 4


Sebastian Dröge (slomo)





          2013-09-09 11:52:57 UTC
        



In gst-plugins-good though:

commit b96d931bf4ce5c3c8c5be4fa76f5c75bca85d0c4
Author: Wim Taymans <wim.taymans@collabora.co.uk>
Date:   Thu Jun 20 14:43:47 2013 +0200

    rtspsrc: fix race in state change to paused
    
    When we go to paused, we first flush the connection and then send the pause
    command. As a result of the flushing, the scheduled paused command can get
    lost. Wait until the connection is completely flushed and the rtsp task is
    waiting before issuing the paused or playing request.
    
    Fixes https://bugzilla.gnome.org/show_bug.cgi?id=702705



Also a blocker for 1.0.11!






Comment 5


Wim Taymans





          2013-09-09 13:18:36 UTC
        



Please try this an reopen if still a problem:

commit 9f9bcbc40578847821412e6949984cdc96ebf77a
Author: Wim Taymans <wim.taymans@collabora.co.uk>
Date:   Mon Sep 9 15:11:51 2013 +0200

    rtspsrc: only wait if we flushed
    
    Only wait for the STREAM_LOCK when we flushed something when sending
    a command for PAUSED or PLAYING.
    
    Fixes https://bugzilla.gnome.org/show_bug.cgi?id=707611