1505139 - Tolerate getenv races in JPEG library initialization

Status: RESOLVED FIXED

(Core Graveyard :: Web Replay, enhancement)

Description

[Brian Hackett [Laid off!]]

Attachment: patch

JPEG library initialization can race when multiple threads compete to perform the initialization --- see the 'FIXME: This code is racy under a multi-threaded environment' comment in media/libjpeg/simd/i386/jsimd.c.  While these races are benign, when recording/replaying them we can get calls to getenv on unpredictable threads, leading to mismatches with the recording and crashes.

Since these races are benign, a proper solution here would be to tolerate getenv calls happening unpredictably during replay.  Technically that is tricky, and for now it seems better to special case this behavior.  The attached patch watches for getenv calls on the environment variables checked during JPEG initialization (which turn features on or off, for testing I guess), and forces those getenv calls to return null without accessing the recording.

Comment 1

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/218da4526e22
Tolerate getenv races in JPEG library initialization, r=lsmyth.

Comment 2

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/mozilla-central/rev/218da4526e22