Bug 175164 – ASSERTION FAILED: writtenAudioDuration >= readAudioDuration in com.apple.WebCore:WebCore::RealtimeOutgoingAudioSource::isReachingBufferedAudioDataHighLimit() + 222

• Component: Media
• Status: RESOLVED FIXED

[Matt Lewis]

The test webrtc/audio-peer-connection-webaudio.html has become a flaky crash on Sierra, El Capitan, and iOS simulator Debug tests according to the dashboard.

https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=webrtc%2Faudio-peer-connection-webaudio.html

https://build.webkit.org/builders/Apple%20Sierra%20Debug%20WK2%20(Tests)/builds/2330
https://build.webkit.org/results/Apple%20Sierra%20Debug%20WK2%20(Tests)/r220178%20(2330)/results.html

The change that caused the failure is most likely: https://trac.webkit.org/changeset/219377/webkit

ASSERTION FAILED: writtenAudioDuration >= readAudioDuration
/Volumes/Data/slave/sierra-debug/build/Source/WebCore/platform/mediastream/mac/RealtimeOutgoingAudioSource.cpp(124) : bool WebCore::RealtimeOutgoingAudioSource::isReachingBufferedAudioDataHighLimit()
1   0x109fd736d WTFCrash
2   0x1133be0fe WebCore::RealtimeOutgoingAudioSource::isReachingBufferedAudioDataHighLimit()
3   0x1133be47c WebCore::RealtimeOutgoingAudioSource::audioSamplesAvailable(WTF::MediaTime const&, WebCore::PlatformAudioData const&, WebCore::AudioStreamDescription const&, unsigned long)
4   0x1133bea39 WebCore::RealtimeOutgoingAudioSource::audioSamplesAvailable(WebCore::MediaStreamTrackPrivate&, WTF::MediaTime const&, WebCore::PlatformAudioData const&, WebCore::AudioStreamDescription const&, unsigned long)
5   0x1133becac non-virtual thunk to WebCore::RealtimeOutgoingAudioSource::audioSamplesAvailable(WebCore::MediaStreamTrackPrivate&, WTF::MediaTime const&, WebCore::PlatformAudioData const&, WebCore::AudioStreamDescription const&, unsigned long)
6   0x11314cebe WebCore::MediaStreamTrackPrivate::audioSamplesAvailable(WTF::MediaTime const&, WebCore::PlatformAudioData const&, WebCore::AudioStreamDescription const&, unsigned long)
7   0x1133aace7 WebCore::RealtimeMediaSource::audioSamplesAvailable(WTF::MediaTime const&, WebCore::PlatformAudioData const&, WebCore::AudioStreamDescription const&, unsigned long)
8   0x1131d7bf9 WebCore::MockRealtimeAudioSourceMac::emitSampleBuffers(unsigned int)
9   0x1131d897b WebCore::MockRealtimeAudioSourceMac::render(double)
10  0x1131d69b9 WebCore::MockRealtimeAudioSource::tick()
11  0x1131d74c5 WTF::RunLoop::Timer<WebCore::MockRealtimeAudioSource>::fired()
12  0x10a027921 WTF::RunLoop::TimerBase::timerFired(__CFRunLoopTimer*, void*)
13  0x7fffafbf4e04 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__
14  0x7fffafbf4a93 __CFRunLoopDoTimer
15  0x7fffafbf45ea __CFRunLoopDoTimers
16  0x7fffafbebfc1 __CFRunLoopRun
17  0x7fffafbeb544 CFRunLoopRunSpecific
18  0x7fffaf14bebc RunCurrentEventLoopInMode
19  0x7fffaf14bcf1 ReceiveNextEventCommon
20  0x7fffaf14bb26 _BlockUntilNextEventMatchingListInModeWithFilter
21  0x7fffad6e4a54 _DPSNextEvent
22  0x7fffade607ee -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:]
23  0x7fffad6d93db -[NSApplication run]
24  0x7fffad6a3e0e NSApplicationMain
25  0x7fffc5b7c8c7 _xpc_objc_main
26  0x7fffc5b7b2e4 xpc_main
27  0x103613105 main
28  0x7fffc5923235 start
29  0x1
LEAK: 4 WebPageProxy

[Radar WebKit Bug Importer]

<rdar://problem/33712305>

[Ryan Haddad]

Created attachment 318449 [details]
Crash log

Just saw this crash with webrtc/peer-connection-remote-audio-mute.html

https://build.webkit.org/results/Apple%20El%20Capitan%20Debug%20WK2%20(Tests)/r220876%20(2609)/results.html

[youenn fablet]

Created attachment 320909 [details]
Patch

[youenn fablet]

This is a tentative fix, I was only able to reproduce the crash once.

[Eric Carlson]

Comment on attachment 320909 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=320909&action=review

> Source/WebCore/platform/mediastream/mac/RealtimeOutgoingAudioSource.cpp:124
> +    ASSERT(writtenAudioDuration + 0.0000001 >= readAudioDuration);

The magic number isn't good, can you use WTF::areEssentiallyEqual() instead?

> Source/WebCore/platform/mediastream/mac/RealtimeOutgoingAudioSource.cpp:133
> +    ASSERT(writtenAudioDuration + 0.0000001 >= readAudioDuration);

Ditto.

[youenn fablet]

Created attachment 320939 [details]
Patch

[youenn fablet]

I was able to reproduce the patch once.
It seems that sometimes at the very beginning we are reading more than what is available. I wonder whether the sample converter is filling with zeros. 

Previous patch was not covering this case.
New patch adds a check to ensure that we do not call pullData if available pushed data is not at least 10ms.
That should fix the crash and improves a bit on efficiency probably.

[youenn fablet]

Created attachment 320940 [details]
Patch

[youenn fablet]

> pushed data is not at least 10ms.

buffered data greater or equal to 10ms.

[WebKit Commit Bot]

Comment on attachment 320940 [details]
Patch

Clearing flags on attachment: 320940

Committed r222109: <http://trac.webkit.org/changeset/222109>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.