Bug 76602 – [chromium] worker-read-blob-async is flaky.

• Status: RESOLVED
• Resolution: FIXED
• Component: DOM

[David Levin]

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#showExpectations=true&tests=fast%2Ffiles%2Fworkers%2Fworker-read-blob-async.html

I did http://trac.webkit.org/changeset/105238 to help us figure this out, so now we know which assert is firing but it is unclear why the test is failing and how the assert/failure are related.

We should probably roll out r105238 when we figure this out. (Even better if we improve asserts so this type of hack wouldn't be needed.)

[David Levin]

More data, I think the line that it the exception is about is here:

http://code.google.com/codesearch#OAMlx_jo-ck/src/third_party/WebKit/LayoutTests/fast/files/workers/resources/worker-apply-blob-url-to-xhr.js&l=32


This line seems clearly incorrect (now) as it calls revokeObjectURL directly instead of doing webkitURL.revokeObjectURL. There are two questions that come from this:
1. Why doesn't this exception happen everytime?
2. Why does the assert fire when this exception gets hit?

[David Levin]

More notes: This is carry over from the previous test and this issue seems to be the reason why fast/files/workers/worker-apply-blob-url-to-xhr.html is always failing.

So the console message is random depending on timing.

It could be that the assert always occurs when a url hasn't been revoked and the worker context is cleaned up but we only happen to hit this during the next test occaisionally.

[David Levin]

Another note:
It looks like DOMURL *leaks* object url's if the destructor is called and DOMURL::contextDestroyed isn't.


 (I would guess that this would be the common case because the WorkerContext should have the last ref to DOMURL and that ref should go away in ~WorkerContext which is before contextDestroyed should be called from ScriptExecutionContext.)

[David Levin]

This no longer repros but I have addressed at least two issues I found (see dependent bugs).

Also the leak is fixed but bug 74386 that fixed it has issues as noted in that bug.

So I'm resolving this one.