1332274 - callback-timeout-with-raf.html test is unstable

Status: REOPENED

(Testing :: web-platform-tests, defect)

Description

[James Graham [:jgraham]]

The html/webappapis/idle-callbacks/callback-timeout-with-raf.html test seems to be unstable so I'm disabling it as part of the import. I haven't looked at the test to decide if this is a test issue or an implementation issue.

Comment 1

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/cf7aaeb55da0
Disable unstable requestIdleCallback test, a=testonly

Comment 2

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/cf7aaeb55da0

Comment 3

[Andreas Farre [:farre]]

I think that this is an implementation issue.

Comment 4

[Andreas Farre [:farre]]

I've been debugging this a bit and I've found some interesting things. There are two reasons for these tests failing.

The first is from the second test only and that is when setting a rIC with a timeout, and then saturating every frame with execution from a rAF, the timeout for the rIC should still trigger and get interleaved with the rAF callbacks. This seems to boil down to the UA being to busy, and if we crank up the number of iterations this works better. If we change the rIC to a regular setTimeout it behaves the same way, i.e. failing the test due to the rAF loop finishing even though the timeout should've happened somewhere in the middle of the loop. This is probably not a bug.

The second is that it seems that sometimes we manage to squeeze in an idle callback even though the rAF callbacks take all the frame to execute. Every case I've seen always happens on the second rAF. If I removed the step_func wrapper for the first rAF call, the failure stopped happening. I had a look at the implementation of step_func, and nothing seems to explain this, but it makes me think that it really is test instability, not an error in the implementation of rIC.