844794 - TSan: Thread data race in nsFactoryEntry::GetFactory() vs nsCOMPtr<nsIFactory>::get()

Status: RESOLVED DUPLICATE of bug 684887

(Core :: XPCOM, defect)

Description

[Christoph Diehl [:posidron]]

Attachment: trace

During Firefox start-up with ThreadSanitizer (LLVM version), we get a data race reported as described in the attached log. Trace was created on mozilla-central with changeset c233837cce08.

According to the TSan devs, most of the reported traces should be real data races, even though they can be "benign". We need to determine if the race can/should be fixed, or put on the ignore list. Even for benign races, TSan devs suggest to fix them (second priority), as they can also cause problems [1].

[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 could be a bug in networking stuff, given that 

    #6 nsStreamTransportService::Init() netwerk/base/src/nsStreamTransportService.cpp:441 (libxul.so+0x0000008b85ce)

is on the stack, using xpcom. Ccing some people for networking.

Comment 2

[Josh Matthews [:jdm]]

This looks like the same race reported in bug 833349.

Comment 3

[Christian Holler (:decoder)]

Very cool, thanks :) We'll wait for the patch in bug 684887 to land then.