967935 - TSan: data race js/src/../../js/src/jsfun.h:109 operator->

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect)

Description

[Christian Holler (:decoder)]

Attachment: Logfile with TSan trace

The attached logfile shows a thread/data race (mozilla-central revision 44ba69cacd7e) 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)]

This seems to be a CodeGenerator vs. Parser race and I've seen threadsafe crashes with the parser during fuzzing. Needinfo from Jason on this.

Comment 2

[Nathan Froyd [:froydnj]]

Haven't seen this one recently; please file a new bug if it turns up again.