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 122820: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 .  http://software.intel.com/en-us/blogs/2013/01/06/benign-data-races-what-could-possibly-go-wrong
Ccing bhackett and billm for some help here :)
JSRuntime::gcNumArenasFreeCommitted can be updated by the background thread and read by the foreground thread. It's used to check whether to trigger a shrinking GC or not in MaybeGC. This is not deterministic anyway so I don't think it's a problem.
Same as for bug 844755 (comment 6), will put these on ignore when bug 847350 is through.
Assignee: nobody → choller
Depends on: 847350
Attachment #823257 - Flags: review?(wmccloskey)
Attachment #823257 - Flags: review?(wmccloskey) → review+
Assignee: choller → jcoppeard
Status: NEW → RESOLVED
Closed: 6 years ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla28
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.
Whiteboard: [tsan][tsan-test-blocker] → [tsan][tsan-test-blocker][qa-]
Whiteboard: [tsan][tsan-test-blocker][qa-] → [tsan][tsan-test-blocker][qa-][adv-main28-]
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