Bug 56315 – SPOD with stalled media element

• Status: NEW
• Component: Media

[Joseph Pecoraro]

Created attachment 85691 [details]
[TEST] Manual Test - Not a complete hang, but should SPOD

Stalling a media element after the meta data causes hang like symptoms (spinner
of death) while the media element progress event timer frequently fires.
Attaching a test case that reproduced this for me.

* SAMPLE:

    8442 Thread_204115   DispatchQueue_1: com.apple.main-thread  (serial)
      8442 0x100009f84
        8442 NSApplicationMain
          8442 -[NSApplication run]
            8442 0x100016062
              8442 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:]
                8442 _DPSNextEvent
                  8442 BlockUntilNextEventMatchingListInMode
                    8442 ReceiveNextEventCommon
                      8442 RunCurrentEventLoopInMode
                        8442 CFRunLoopRunSpecific
                          8442 __CFRunLoopRun
                            7262 WebCore::timerFired(__CFRunLoopTimer*, void*)
                              7258 WebCore::ThreadTimers::sharedTimerFiredInternal()
                                7257 WebCore::HTMLMediaElement::progressEventTimerFired(WebCore::Timer<WebCore::HTMLMediaElement>*)
                                  7257 WebCore::MediaPlayerPrivateQTKit::bytesLoaded() const
                                    6484 WebCore::MediaPlayerPrivateQTKit::duration() const
                                      6484 -[QTMovie duration]
                                        6484 -[QTMovie_QuickTime duration]
                                          6484 timeFromServerWithSelector
                                            6484 getQTTime
                                              6484 mach_msg
                                                6484 mach_msg_trap
                                    771 WebCore::MediaPlayerPrivateQTKit::totalBytes() const
                                      771 -[QTMovie attributeForKey:]
                                        771 QTMovieAttributesGetAttribute
                                          771 -[QTMovie_QuickTime dataSize]
                                            771 dataSize
                                              771 mach_msg
                                                771 mach_msg_trap

* STEPS TO REPRODUCE:

  1. cd webkit root
  2. Place in ./LayoutTests/http/tests/media/video-play-stall-after-meta-data.html
  3. Run ./Tools/Scripts/run-webkit-httpd
  4. Open 127.0.0.1:8000/media/video-play-stall-after-meta-data.html in Safari.

* NOTES:
• I don't know if we can write a reliable test case for this that DumpRenderTree will catch.
• The window.onload event doesn't fire, I am working on a separate bug to fix that.

[Eric Carlson]

Every time QuickTime (in QTKitServer) is idled, it gives time to the video pipeline which tries to load the data for the first frame. This read is synchronous so it blocks the call we make to QTKit to get the duration.

Call graph:
    2167 Thread_1011186   DispatchQueue_1: com.apple.main-thread  (serial)
      2167 start
        2167 main
          2167 CFRunLoopRun
            2167 CFRunLoopRunSpecific
              2167 __CFRunLoopRun
                2158 __NSFireTimer
                  2158 +[QTMovie_QuickTime idleAllMovies:]
                    2158 -[QTMovie_QuickTime idle]
                      2158 QTObjectTokenExecuteCommand
                        2158 QTSendToObject
                          2158 QTObjectTokenPriv::DispatchMessage(QTMessagePriv*, void const*, __CFAllocator const*, unsigned long, unsigned long, ComponentMsgParam*, unsigned long, unsigned long)
                            2158 QTObjectTokenPriv::SendMessageToObject(QTMessagePriv*, unsigned long)
                              2158 DispatchQTMsg(void const*, unsigned long, unsigned long, unsigned long, QTOGenericObject*)
                                2158 QTOMovieObject::SendCommand(unsigned long, void const*)
                                  2158 MCIdle
                                    2158 CallComponentDispatch
                                      2158 _MCComponentDispatch
                                        2158 CallComponentFunctionCommonWithStorage(char**, ComponentParameters*, long (*)(), unsigned long)
                                          2158 _MCIdle
                                            2158 internalDoAction
                                              2158 doIdleMovie
                                                2158 TaskMovie_priv
                                                  2158 MediaMoviesTask
                                                    2158 CallComponentDispatch
                                                      2158 Video2ComponentDispatch
                                                        2158 CallComponentFunctionCommonWithStorage(char**, ComponentParameters*, long (*)(), unsigned long)
                                                          2158 callComponentStorage_44444
                                                            2158 Video2MoviesTask
                                                              2158 v2m_doWhatTheMentorTellsUs
                                                                2158 QueueAFrame
                                                                  2158 DataHFinishData
                                                                    2158 CallComponentDispatch
                                                                      2158 HTTPDataHandler_ComponentDispatch
                                                                        2158 CallComponentFunctionCommonWithStorage(char**, ComponentParameters*, long (*)(), unsigned long)
                                                                          2158 HTTPDataHandler_FinishData
                                                                            2155 HTTPDhlr_ReadSYNC


We should be caching the duration immediately and only reading it when we know the movie has been edited like we do in the new AVFoundation backend.