1124411 - Deadlock in cubeb_wasapi backend

Status: RESOLVED FIXED

(Core :: Audio/Video, defect)

Description

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

Attachment: Stacks

See the attachment for stacks.  The audio backend appears to have deadlocked itself during shutdown (see the two wasapi threads) and one of them was holding the decoder monitor so that eventually deadlocks the main thread.

Comment 1

[JW Wang [:jwwang] [:jw_wang]]

Which wasapi thread was holding the decoder monitor? I can't see it from the stack.

Comment 2

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

The one calling wasapi_stream_stop.  http://hg.mozilla.org/mozilla-central/annotate/34e2d2bd7ec4/dom/media/AudioSink.cpp#l200

Comment 3

[JW Wang [:jwwang] [:jw_wang]]

wasapi_stream_render_loop() stuck in WaitForMultipleObjects while wasapi_stream_stop() stuck in |WaitForSingleObject(stm->thread, INFINITE);| which happened after |SetEvent(stm->shutdown_event);| which should notify wasapi_stream_render_loop()... this is weird.

Comment 4

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

Yeah, I didn't really understand why the render_loop didn't quit.

Comment 5

[Chris Pearce [:cpearce (Not reading bugmail)]]

Paul/Matthew: Any ideas?

Comment 6

[Paul Adenot (:padenot)]

I've been re-reading this code, but it looks correct.

We could add a (rather high, like 1000ms) timeout to the WaitForMultipleObject (which is guaranteed to unblock at least every 30ms, and is on a very high priority thread), to see what happens. And maybe adding a assert somewhere where we could get the state of the stream in crash stats or something.

Comment 7

[Matthew Gregan [:kinetik]]

Paul's idea sounds good to me.

Comment 8

[Paul Adenot (:padenot)]

Attachment: Add timeout when calling WaitForMultipleObjects to wallpaper over a deadlock. r=

Comment 9

[Matthew Gregan [:kinetik]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=07fa6a27780a

Comment 10

[Matthew Gregan [:kinetik]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/c841c87a7791

Comment 11

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/c841c87a7791