RESOLVED FIXED 173515
REGRESSION(r218438): Caused imported/w3c/web-platform-tests/media-source/mediasource* tests to fail (Requested by smfr on #webkit). 
https://bugs.webkit.org/show_bug.cgi?id=173515
Summary REGRESSION(r218438): Caused imported/w3c/web-platform-tests/media-source/medi...
WebKit Commit Bot
Reported 2017-06-17 12:47:42 PDT
http://trac.webkit.org/changeset/218438 broke the build: Caused imported/w3c/web-platform-tests/media-source/mediasource* tests to fail (Requested by smfr on #webkit). This is an automatic bug report generated by webkitbot. If this bug report was created because of a flaky test, please file a bug for the flaky test (if we don't already have one on file) and dup this bug against that bug so that we can track how often these flaky tests fail.
Attachments
ROLLOUT of r218438 (2.01 KB, patch)
2017-06-17 12:47 PDT, WebKit Commit Bot 		no flags
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
WebKit Commit Bot
Comment 1 2017-06-17 12:47:46 PDT
Created attachment 313207 [details] ROLLOUT of r218438 Any committer can land this patch automatically by marking it commit-queue+. The commit-queue will build and test the patch before landing to ensure that the rollout will be successful. This process takes approximately 15 minutes. If you would like to land the rollout faster, you can use the following command: webkit-patch land-attachment ATTACHMENT_ID where ATTACHMENT_ID is the ID of this attachment.
Simon Fraser (smfr)
Comment 2 2017-06-17 12:48:37 PDT
Comment on attachment 313207 [details] ROLLOUT of r218438 Failures: https://build.webkit.org/results/Apple%20Sierra%20Release%20WK1%20(Tests)/r218438%20(2552)/results.html also affecting EWS
WebKit Commit Bot
Comment 3 2017-06-17 12:50:54 PDT
Comment on attachment 313207 [details] ROLLOUT of r218438 Clearing flags on attachment: 313207 Committed r218454: <http://trac.webkit.org/changeset/218454>
WebKit Commit Bot
Comment 4 2017-06-17 12:50:55 PDT
All reviewed patches have been landed. Closing bug.
Jer Noble
Comment 5 2017-06-17 22:58:39 PDT
I found the underlying issue behind the test failures, and it has nothing to do with this patch, except in that this patch causes it to happen much more frequently. When a client specifies a timestamp offset, the SourceBuffer code stores the current presentation time as a float (because a MediaTime + float = float). But the sample itself store it as a MediaTime. Generally speaking, we use the sample's presentation time as the key to our storage, but in one instance (the decodeQueue) we are using the local value of presentation time (the float). This leads to a mismatch later when it comes time to remove those samples from the decode queue, so the samples are left in the decode queue, which causes a decode error, which breaks this test.
Jer Noble
Comment 6 2017-06-17 22:59:32 PDT
(BTW, I'm pretty sure that this is the cause of some existing flakiness of some of these tests.)
Jer Noble
Comment 7 2017-06-17 23:00:01 PDT
Gah, I should really be commenting in the related radar. :(
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