1132212 - TSan: data race netwerk/protocol/nsHttpTransaction.cpp:605 Caps

Status: RESOLVED FIXED

(Core :: Networking: HTTP, defect)

Description

[Nathan Froyd [:froydnj]]

Attachment: http-race.txt

[cribbing from decoder's script, hopefully he won't mind]

The attached logfile shows a thread/data race 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 unacceptable 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

[Patrick McManus [:mcmanus]]

Thanks Nathan. I think I can figure this out - but if you have a cset for that build it would be helpful.. some line numbers have changed a bit I think.

Comment 2

[Patrick McManus [:mcmanus]]

never mind about the cset - its obvious what the cause is.. and its intentional (which makes it easy to identify at least!). Though based on this I'll look at changing it.

Comment 3

[Patrick McManus [:mcmanus]]

Attachment: nshttptransction.cpp dont play with data race fire

Comment 4

[Patrick McManus [:mcmanus]]

steve, can you help with this review? Its changing code I'm pretty sure we cooked up together.

you'd have a try run if try wasn't CLOSED TREE :(

Comment 5

[Steve Workman [:sworkman] (INACTIVE)]

Comment on attachment 8563574 [details] [diff] [review]
nshttptransction.cpp dont play with data race fire

Review of attachment 8563574 [details] [diff] [review]:
-----------------------------------------------------------------

Ah, yes. Looks sane to me. r=me pending try :)

Comment 6

[Patrick McManus [:mcmanus]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=7383619a2671

Comment 7

[Patrick McManus [:mcmanus]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/216e9a560a66

Comment 8

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/216e9a560a66