Bug 4784 – Wrong order in calls when using setInterval and setTimeout

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Thomas Fuchs]

If multiple simultaneous calls are made to setInterval/setTimeout Safari begins to execute JavaScript in a 
wrong order and starts to neclect earlier setInterval intervals.

See the provided URL for a test case. Click on "DropOut" by the black boxes for the most noticeable 
problem that is causes by this bug.

For a correctly working implementation, see the URL in Firefox 1.0.X or Firefox DP 2.

[Thomas Fuchs]

"DropOut" also works fine on the black boxes in Internet Explorer 6 on W2K.

[Mark Rowe (bdash)]

I can see the problem that you describe, but without a significantly reduced test case it's not easy to say 
whether your diagnosis is accurate.  Are you able to come up with a reduced test case that demonstrates 
the problem?  http://webkit.opendarwin.org/quality/reduction.html has more info if you need it.

I'm confirming this as our behaviour differs substantially from Firefox.

[Thomas Fuchs]

Created attachment 3709 [details]
Testcase

This is a test case showing that Safari has wildly varying timing when
setInterval is called multiple times.

If I can I'll come up with an even tighter test case.

Example:
IntervalTimer #0: 6 iterations, avg. delta: 38.666666666666664, min: 5, max: 58

IntervalTimer #1: 6 iterations, avg. delta: 152.83333333333334, min: 5, max:
735
IntervalTimer #2: 5 iterations, avg. delta: 184.8, min: 39, max: 741
(...)
IntervalTimer #13: 4 iterations, avg. delta: 40.25, min: 40, max: 41
(...)
IntervalTimer #98: 4 iterations, avg. delta: 212.25, min: 35, max: 723
IntervalTimer #99: 4 iterations, avg. delta: 213.75, min: 34, max: 730

On Firefox DP 2, results are consistent:
IntervalTimer #0: 11 iterations, avg. delta: 89.18181818181819, min: 77, max:
143
IntervalTimer #1: 11 iterations, avg. delta: 89.0909090909091, min: 77, max:
143
IntervalTimer #2: 11 iterations, avg. delta: 89.0909090909091, min: 77, max:
143
IntervalTimer #3: 11 iterations, avg. delta: 89, min: 77, max: 143
IntervalTimer #4: 11 iterations, avg. delta: 89.0909090909091, min: 77, max:
143
IntervalTimer #5: 11 iterations, avg. delta: 89.0909090909091, min: 77, max:
144
(...)
IntervalTimer #98: 11 iterations, avg. delta: 89.45454545454545, min: 77, max:
133
IntervalTimer #99: 11 iterations, avg. delta: 89.45454545454545, min: 77, max:
133

[David Kilzer (:ddkilzer)]

See also Bug 7099.

I think r12774 (fix for bug 7209) fixed this.