939789 - TSan: data race dom/base/nsJSEnvironment.cpp:2576 nsJSContext::LikelyShortLivingObjectCreated()

Status: RESOLVED FIXED

(Core :: DOM: Events, defect)

Description

[Christian Holler (:decoder)]

Attachment: Logfile with TSan trace

The attached logfile shows a thread/data race (mozilla-central revision beddd6d4bcdf) detected by TSan (ThreadSanitizer).

Typically, races reported by TSan are not false positives, but it is possible that the race is benign. Even in this case though, we should try to come up with a fix unless this would cause inacceptable performance issues. Also note that seemingly benign races can possibly be harmful (also depending on the compiler and the architecture) [1].

If the bug cannot be fixed, then this bug should be used to either make a compile-time annotation for blacklisting or add an entry to the runtime blacklist.

[1] http://software.intel.com/en-us/blogs/2013/01/06/benign-data-races-what-could-possibly-go-wrong

Comment 1

[Christian Holler (:decoder)]

Forgot to set needinfo, based on hg blame.

Comment 2

[Andrew McCreight [:mccr8]]

LikelyShortLivingObjectCreated is getting called from a worker.

Comment 3

[Olli Pettay [:smaug][[e-mail]]]

Yeah, this we should fix. Luckily not a critical issue, since the method call just gives a hint.

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

Attachment: patch

Just move the call a bit earlier in the method where we set mIsMainThreadEvent.

Comment 5

[Olli Pettay [:smaug][[e-mail]]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/f921dc945f7b

Comment 6

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

https://hg.mozilla.org/mozilla-central/rev/f921dc945f7b

Comment 7

[u279076]

De-prioritizing QA verification of this bug. Please remove the [qa-] whiteboard tag and add the verifyme keyword if you think this needs our attention before Firefox 28 is released.