Created attachment 328644 [details] Crash Log The test webaudio/silent-audio-interrupted-in-background.html has crashed with an assertion several times on Sierra Debug WK1: https://build.webkit.org/results/Apple%20Sierra%20Debug%20WK1%20(Tests)/r225592%20(5152)/results.html https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=webaudio%2Fsilent-audio-interrupted-in-background.html stderr: ASSERTION FAILED: m_sourceSampleRate == sampleRate() /Volumes/Data/slave/sierra-debug/build/Source/WebCore/Modules/webaudio/MediaElementAudioSourceNode.cpp(128) : virtual void WebCore::MediaElementAudioSourceNode::process(size_t) 1 0x10c2bd66d WTFCrash 2 0x115dc6ba8 WebCore::MediaElementAudioSourceNode::process(unsigned long) 3 0x115dacb3a WebCore::AudioNode::processIfNecessary(unsigned long) 4 0x115daf2b9 WebCore::AudioNodeOutput::pull(WebCore::AudioBus*, unsigned long) 5 0x115dad133 WebCore::AudioNodeInput::pull(WebCore::AudioBus*, unsigned long) 6 0x115dad062 WebCore::AudioNode::pullInputs(unsigned long) 7 0x115daca8c WebCore::AudioNode::processIfNecessary(unsigned long) 8 0x115daf2b9 WebCore::AudioNodeOutput::pull(WebCore::AudioBus*, unsigned long) 9 0x115daf0bb WebCore::AudioNodeInput::sumAllConnections(WebCore::AudioBus*, unsigned long) 10 0x115dad185 WebCore::AudioNodeInput::pull(WebCore::AudioBus*, unsigned long) 11 0x115d95b7a WebCore::AudioDestinationNode::render(WebCore::AudioBus*, WebCore::AudioBus*, unsigned long) 12 0x115d95d5f non-virtual thunk to WebCore::AudioDestinationNode::render(WebCore::AudioBus*, WebCore::AudioBus*, unsigned long) 13 0x116eb18ca WebCore::AudioDestinationMac::render(unsigned int, AudioBufferList*) 14 0x116eb1717 WebCore::AudioDestinationMac::inputProc(void*, unsigned int*, AudioTimeStamp const*, unsigned int, unsigned int, AudioBufferList*) 15 0x138a0cef5 AUInputElement::PullInput(unsigned int&, AudioTimeStamp const&, unsigned int, unsigned int) 16 0x1389038a8 AUInputFormatConverter2::InputProc(OpaqueAudioConverter*, unsigned int*, AudioBufferList*, AudioStreamPacketDescription**, void*) 17 0x7fffa44d343b AudioConverterChain::CallInputProc(unsigned int) 18 0x7fffa44d3198 AudioConverterChain::FillBufferFromInputProc(unsigned int*, CABufferList*) 19 0x7fffa44d30fc BufferedAudioConverter::GetInputBytes(unsigned int, unsigned int&, CABufferList const*&) 20 0x7fffa44d2fc0 CBRConverter::RenderOutput(CABufferList*, unsigned int, unsigned int&, AudioStreamPacketDescription*) 21 0x7fffa44c65fd BufferedAudioConverter::FillBuffer(unsigned int&, AudioBufferList&, AudioStreamPacketDescription*) 22 0x7fffa44c68c1 AudioConverterChain::RenderOutput(CABufferList*, unsigned int, unsigned int&, AudioStreamPacketDescription*) 23 0x7fffa44c65fd BufferedAudioConverter::FillBuffer(unsigned int&, AudioBufferList&, AudioStreamPacketDescription*) 24 0x7fffa44c60ce AudioConverterFillComplexBuffer 25 0x13890335f AUInputFormatConverter2::PullAndConvertInput(AudioTimeStamp const&, unsigned int&, AudioBufferList&, AudioStreamPacketDescription*, bool&) 26 0x1389031a8 AUConverterBase::RenderBus(unsigned int&, AudioTimeStamp const&, unsigned int, unsigned int) 27 0x138a10084 AUBase::DoRenderBus(unsigned int&, AudioTimeStamp const&, unsigned int, AUOutputElement*, unsigned int, AudioBufferList&) 28 0x138a0fd84 AUBase::DoRender(unsigned int&, AudioTimeStamp const&, unsigned int, unsigned int, AudioBufferList&) 29 0x1389062de AUHAL::AUIOProc(unsigned int, AudioTimeStamp const*, AudioBufferList const*, AudioTimeStamp const*, AudioBufferList*, AudioTimeStamp const*, void*) 30 0x7fffa52338ce HALC_ProxyIOContext::IOWorkLoop() 31 0x7fffa5232264 HALC_ProxyIOContext::IOThreadEntry(void*) The first crash happened with this build: https://build.webkit.org/builders/Apple%20Sierra%20Debug%20WK1%20(Tests)/builds/4780