Bug 221129 – Flaky JSC test: stress/shared-array-buffer-sort-while-different-thread-is-modifying.js.default

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

[Michael Catanzaro]

JSC stress test is flaky on Red Hat's internal CI (which runs with JIT disabled and cloop enabled). The first known failure was Dec 13. I didn't report it until now because until earlier this week, all the failures occurred on ppc64le, so I incorrectly assumed the issue was specific to that architecture. But the test has since failed on both s390x and x86_64 as well, so it's a more general problem.

Unfortunately, the error message is pretty generic:

Running stress/shared-array-buffer-sort-while-different-thread-is-modifying.js.default
stress/shared-array-buffer-sort-while-different-thread-is-modifying.js.default: Exception: JavaScript execution terminated.
stress/shared-array-buffer-sort-while-different-thread-is-modifying.js.default: ERROR: Unexpected exit code: 1
FAIL: stress/shared-array-buffer-sort-while-different-thread-is-modifying.js.default

I don't know what to make of "JavaScript execution terminated," but it's this same error on all architectures.

Based on the failure history, it might be due to some change that landed in trunk during early December:

Dec 13: failed on ppc64le
Jan 5: failed on ppc64le
Jan 8: failed on ppc64le
Jan 19: failed on ppc64le
Jan 26: failed on s390x
Jan 29: failed on s390x and x86_64

[Radar WebKit Bug Importer]

<rdar://problem/74023276>

[Michael Catanzaro]

Created attachment 419715 [details]
Patch

[Michael Catanzaro]

(In reply to Michael Catanzaro from comment #0)
> Based on the failure history, it might be due to some change that landed in
> trunk during early December:
> 
> Dec 13: failed on ppc64le
> Jan 5: failed on ppc64le
> Jan 8: failed on ppc64le
> Jan 19: failed on ppc64le
> Jan 26: failed on s390x
> Jan 29: failed on s390x and x86_64

Feb 2: failed on s390x
Feb 6: failed on x86_64

[Michael Catanzaro]

Sadly this is going to be very difficult to track down. I am currently running this test in a continuous loop on (a) my desktop, and (b) the s390x server that we use for our internal CI (since it seems to fail more often on this server than it does for x86_64). Sadly the test passes every time. Since it is a timing issue, I bet it only fails when the tests are run all at once instead of one at a time. I was hoping to bisect it, but it doesn't fail often enough for it to be practical to bisect in this way.

[Michael Catanzaro]

This test is still flaky on all architectures:

Feb 13: failed on ppc64le
Feb 14: failed on s390x
Feb 15: failed on s390x
Feb 19: failed on ppc64le
Feb 20: failed on aarch64
March 1: failed on ppc64le

[Michael Catanzaro]

Comment on attachment 419715 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=419715&action=review

> JSTests/stress/shared-array-buffer-sort-while-different-thread-is-modifying.js:3
> +//@ skip
>  //@ runDefault("--watchdog=1000", "--watchdog-exception-ok")
> +// FIXME: unskip this test when https://bugs.webkit.org/show_bug.cgi?id=221129 is fixed.

Can we land this...?

[Yusuke Suzuki]

@Michael Thanks. Could you paste the crash trace of the failure?

[Michael Catanzaro]

Unfortunately I don't think it's crashing because the process exit status is 1. If there was a crash, the exit status would be (128 + signal value). So we don't have much to go on other than the stdout/stderr in comment #0.

[Yusuke Suzuki]

OK, "JavaScript execution terminated" this sounds like this is not a real bug. Possibly, the thread is terminated, and we are not properly handling that case in jsc shell...?

[Yusuke Suzuki]

Created attachment 422016 [details]
Patch

[Yusuke Suzuki]

Created attachment 422019 [details]
Patch

[Michael Catanzaro]

Comment on attachment 422019 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=422019&action=review

Thanks Yusuke!

> Source/JavaScriptCore/jsc.cpp:416
> +    CommandLine(CommandLineForWorkersTag);

This could use: explicit

[Yusuke Suzuki]

Comment on attachment 422019 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=422019&action=review

Thanks!

>> Source/JavaScriptCore/jsc.cpp:416
>> +    CommandLine(CommandLineForWorkersTag);
> 
> This could use: explicit

Fixed.

[Yusuke Suzuki]

Committed r273779 (234776@main): <https://commits.webkit.org/234776@main>