Bug 11350 – http/tests/incremental/slow-utf8-css sometimes coalesces RenderTexts

• Status: RESOLVED
• Resolution: FIXED
• Component: Tools / Tests

[Adam Roben (:aroben)]

http/tests/incremental/slow-utf8-css is intermittently failing. The symptom is that adjacent RenderTexts are sometimes being coalesced into one RenderText. It has been theorized that this is due to variances in the speed that chunks of data are sent to DumpRenderTree by Apache.

[Geoffrey Garen]

To verify, I ran this command:
run-webkit-tests http/tests/incremental/slow-utf8-css.pl http/tests/incremental/slow-utf8-css.pl

The first test passed. The second test failed, with identical results to the buildbot. I've attached a tcpdump of the back-to-back transactions.

[Geoffrey Garen]

Created attachment 11144 [details]
tcpdump of pass then fail

[Geoffrey Garen]

The traffic is slightly different in the two transactions but, as far as I can tell, the chunks sent by the server are identical.

[Alexey Proskuryakov]

As discussed on IRC, coalesced RenderTexts mean that all data was processed in one pass, so the test isn't actually performed (it checks for a bug where Decoder only processed one chunk correctly for CSS).

If the solution with inserting a small timeout won't work, we can also try converting the test into an HTML+CSS one - then timing won't matter.

[Geoffrey Garen]

Created attachment 11151 [details]
patch-o-rama

[Geoffrey Garen]

I suspect the issue was that the test depended on a WebCore timer. Inserting a delay ensure that the timer fires consistently between the chunks of data.

[Geoffrey Garen]

r17141