981126 - prevent glxtest child process from executing the normal shutdown sequence

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Viktor Stanchev [:vikstrous]]

Right now the child process spawned by the glx test on Linux is making firefox shut down normally, which causes the profiler (given the MOZ_PROFLIER_SHUTDOWN environment variable) to try to write out its profile to disk. This leads to a deadlock on some operating systems. I was able to reproduce it on Ubuntu with kernel 3.2.0-45 and not on Arch Linux with 3.13.5-1-ARCH. The deadlock was happening on Talos, which was our original problem.

We can't shut down the profiler either because that involves acquiring a lock. The only sane way to fix this appears to be to not execute the usual shut down sequence in the child process.

Comment 1

[Viktor Stanchev [:vikstrous]]

Attachment: glxtest

Comment 2

[Viktor Stanchev [:vikstrous]]

https://tbpl.mozilla.org/?tree=Try&rev=25e31e85b370

Comment 3

[Benoit Girard (:BenWa)]

Comment on attachment 8387861 [details] [diff] [review]
glxtest

Review of attachment 8387861 [details] [diff] [review]:
-----------------------------------------------------------------

::: toolkit/xre/glxtest.cpp
@@ +260,4 @@
>        close(pfd[1]);
>        return false;
>    }
> +  // the child exits early to avoid running to full shutdown sequence

// to avoid conflicting with threads we have already spanned (like the profiler).

Comment 4

[Jeff Muizelaar [:jrmuizel]]

Comment on attachment 8387861 [details] [diff] [review]
glxtest

Review of attachment 8387861 [details] [diff] [review]:
-----------------------------------------------------------------

This is what I would've expected in the first place

Comment 5

[Viktor Stanchev [:vikstrous]]

Attachment: glxtest

Updated comment. Does anyone else need to review this?

Comment 6

[Benoit Girard (:BenWa)]

No, adding to my landing queue. Waiting on inbound.

Comment 7

[Benoit Girard (:BenWa)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/d736ff28e9dc

Comment 8

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/d736ff28e9dc