Bug 188357 – REGRESSION (r234330): 3 legacy-animation-engine/compositing tests are flaky failures

• Component: New Bugs
• Status: RESOLVED FIXED

[Ryan Haddad]

From https://bugs.webkit.org/show_bug.cgi?id=187866

Truitt Savell 2018-07-30 10:27:14 PDT
It looks like there are three tests on High Sierra WK1 that are continuing to fail consistently after https://trac.webkit.org/changeset/234330/webkit. The tests are flakey on other WK1 release platforms.

Tests:
legacy-animation-engine/compositing/backing/transform-transition-from-outside-view.html 
legacy-animation-engine/compositing/geometry/limit-layer-bounds-opacity-transition.html 
legacy-animation-engine/compositing/layer-creation/animation-overlap-with-children.html

Test History
https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=legacy-animation-engine%2Fcompositing%2Fbacking%2Ftransform-transition-from-outside-view.html%20legacy-animation-engine%2Fcompositing%2Fgeometry%2Flimit-layer-bounds-opacity-transition.html%20legacy-animation-engine%2Fcompositing%2Flayer-creation%2Fanimation-overlap-with-children.html

Text Diffs:
https://build.webkit.org/results/Apple%20High%20Sierra%20Release%20WK1%20(Tests)/r234363%20(7001)/legacy-animation-engine/compositing/backing/transform-transition-from-outside-view-diff.txt

https://build.webkit.org/results/Apple%20High%20Sierra%20Release%20WK1%20(Tests)/r234363%20(7001)/legacy-animation-engine/compositing/geometry/limit-layer-bounds-opacity-transition-diff.txt

https://build.webkit.org/results/Apple%20High%20Sierra%20Release%20WK1%20(Tests)/r234363%20(7001)/legacy-animation-engine/compositing/layer-creation/animation-overlap-with-children-diff.txt

[Simon Fraser (smfr)]

I reproduces two flakes and am fixing in bug 188356, but I could not reproduce all of these.

[Radar WebKit Bug Importer]

<rdar://problem/42986633>

[Simon Fraser (smfr)]

I can only reproduce flakiness with:
legacy-animation-engine/animations/needs-layout.html failed unexpectedly (reference mismatch)                 
legacy-animation-engine/animations/trigger-container-scroll-empty.html failed unexpectedly (text diff)

[Truitt Savell]

Created attachment 346717 [details]
Repro Test List

Here is a reliable repro of the Three tests that are failing. A state is being set and this list order reliably reproduces the failure. I ran this list of tests using:

run-webkit-tests --test-list DIRECTORY_OF_TEST_LIST_FILE --child-processes 1 -1

I am going to try and bisect the list and see if I can get a better idea of what's causing this.

[Truitt Savell]

These tests are causing the failures:

js/slow-stress/Int32Array-alloc-large-long-lived.html
js/slow-stress/Int32Array-alloc-huge.html
js/slow-stress/Int32Array-alloc-huge-long-lived.html
 
legacy-animation-engine/compositing/backing/transform-transition-from-outside-view.html
legacy-animation-engine/compositing/geometry/limit-layer-bounds-opacity-transition.html
legacy-animation-engine/compositing/layer-creation/animation-overlap-with-children.html

Running these tests together causes the legacy-animation tests to fail. The js/ tests can be ran in any order but all three of them together cause the state that is making the three legacy tests fail.

[Simon Fraser (smfr)]

It looks like the legacy-animation-engine/compositing test are responding to memory pressure, but DRT is supposed to override the compositing policy option. That must be broken somehow.

[Simon Fraser (smfr)]

The bug here is that the Internals code to reset state between tests clears the compositing policy override, allowing a test to fall into low memory mode. In WTR, we explicitly set the override to "Normal", but there is no such code in DRT.

[Truitt Savell]

Marking these three tests flakey in https://trac.webkit.org/changeset/234742/webkit

doing this to clear noise on the tree while a solution is found.

[Simon Fraser (smfr)]

Created attachment 368284 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 368284 [details]
Patch

Clearing flags on attachment: 368284

Committed r244675: <https://trac.webkit.org/changeset/244675>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Alexey Proskuryakov]

*** Bug 188421 has been marked as a duplicate of this bug. ***

[Alexey Proskuryakov]

*** Bug 188910 has been marked as a duplicate of this bug. ***

[Alexey Proskuryakov]

This patch fixed two of these tests, and it also fixed other tests that I just duped here.

legacy-animation-engine/compositing/backing/transform-transition-from-outside-view.html remains super flaky. Turns out that we already have a separate bug for it, bug 184611, but failures are not as before.

Updated test results in http://trac.webkit.org/r245211