Bug 222371 – [ macOS Wk2 ] imported/w3c/web-platform-tests/media-source/mediasource-activesourcebuffers.html is a flakey text failure

• Component: New Bugs
• Status: REOPENED

[Robert Jenner]

imported/w3c/web-platform-tests/media-source/mediasource-activesourcebuffers.html

is a flakey text failure in macOS in release and debug on Wk2. It Is also occurring on EWS, and slowing it down.  

HISTORY URL:
https://results.webkit.org/?suite=layout-tests&test=imported%2Fw3c%2Fweb-platform-tests%2Fmedia-source%2Fmediasource-activesourcebuffers.html&platform=mac

DIFF URL:
https://build.webkit.org/results/Apple-BigSur-Release-WK2-Tests/r273378%20(471)/imported/w3c/web-platform-tests/media-source/mediasource-activesourcebuffers-pretty-diff.html

DIFF TEXT:
--- /Volumes/Data/slave/bigsur-release-tests-wk2/build/layout-test-results/imported/w3c/web-platform-tests/media-source/mediasource-activesourcebuffers-expected.txt
+++ /Volumes/Data/slave/bigsur-release-tests-wk2/build/layout-test-results/imported/w3c/web-platform-tests/media-source/mediasource-activesourcebuffers-actual.txt
@@ -5,6 +5,6 @@
 PASS Active SourceBuffers must appear in the same order as they appear in the sourceBuffers attribute: audio is first sourceBuffer, video media appended first
 PASS Active SourceBuffers must appear in the same order as they appear in the sourceBuffers attribute: video is first sourceBuffer, audio media appended first
 PASS Active SourceBuffers must appear in the same order as they appear in the sourceBuffers attribute: video is first sourceBuffer, video media appended first
-PASS Active SourceBuffers list reflects changes to selected audio/video tracks associated with separate SourceBuffers.
+FAIL Active SourceBuffers list reflects changes to selected audio/video tracks associated with separate SourceBuffers. assert_equals: audio source buffer no longer in the activeSourceBuffers list expected 1 but got 2
 PASS Active SourceBuffers list ignores changes to selected audio/video tracks that do not affect the activation of the SourceBuffer.

[Radar WebKit Bug Importer]

<rdar://problem/74704447>

[Robert Jenner]

Created attachment 421438 [details]
Patch

[Robert Jenner]

Was able to reproduce failure at tip of tree using the following test:

run-webkit-test imported/w3c/web-platform-tests/media-source/mediasource-activesourcebuffers.html  --iterations 1000 -f

Same failure occurred:
+FAIL Active SourceBuffers list reflects changes to selected audio/video tracks associated with separate SourceBuffers. assert_equals: audio source buffer no longer in the activeSourceBuffers list expected 1 but got 2

Have not tracked to an obvious regress point yet. The test has been flakey for a while, but there is a point where it started to fail more frequently. Currently investigating.

[EWS]

Committed r273433: <https://commits.webkit.org/r273433>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 421438 [details].

[Truitt Savell]

reopen

[Robert Jenner]

After investigating I have bisected to a regression point of r272842. 

Running the following test:
run-webkit-test imported/w3c/web-platform-tests/media-source/mediasource-activesourcebuffers.html  --iterations 1000 -f

The same failure was reproduced. When running on r272841, the failure was not reproduced. The test was flakey failing before. However, it failed more frequently after r272842.

[Robert Jenner]

I have added Crash to the test expectations for this test because it has been sporadically crashing.

https://trac.webkit.org/changeset/276101/webkit