846082 - Hang at shutdown after using mozGetUserMedia()

Status: RESOLVED DUPLICATE of bug 845842

(Core :: WebRTC: Audio/Video, defect)

Description

[Randell Jesup [:jesup] (needinfo me)]

Attachment: gdb log from one session

hg bisect says the first bad patch has to be in the range 122579:b831500ca4be (122578 was good) to 122582:6c126d076b0d (bad) (which was a backout of 122579). The other two patches bisect shows were 122580:437c955ff06d (bug 796114 - Inline with type-checked arguments. r=h4writer), and a GPS patch to a bunch of metrics jsm stuff (Bug 841074 - Statically declare fields on FHR measurements; r=rnewman 122581:5054f997ef77)

STR: (Fedora 17 x64)

hg update -r 6c126d076b0d
build
start up
got to http://mozilla.github.com/webrtc-landing/gum_test.html
Click on Video
Tell it you allow capture
Click Stop
Click close-window

Comment 1

[Randell Jesup [:jesup] (needinfo me)]

Amazingly, this hang on shutdown is due to bug 841074.   Backing it out removes the hang (verified on the first broken build, and on current inbound head).  When I use an all:5 logging, the last non-idle logging I see is the MediaStreamGraph finishing shutting down successfully.

Perhaps there's some oddball interaction with the metrics data in my profile?

CC-ing some people who might have ideas or be peripherally involved (MediaStreamGraph, GC/CC, general XPCOM shutdown).

(To clarify the initial report: Shutdown hangs for me 100% consistently on builds on or after 122581:5054f997ef77, IF (and only if, it appears) I started a getUserMedia stream (and stopped it).  See the STR above.

Comment 2

[Randell Jesup [:jesup] (needinfo me)]

Attachment: backout rev 5054f997ef77 (bug 841074) for hanging shutdown after mozGetUserMedia()

Comment 3

[Gregory Szorc [:gps]]

The hang was reported in bug 845842. The technical discussion about the underlying problem is there. A treatment of the symptoms (read: no more hang) landed in bug 845966. Unfortunately, it appears nobody performed an inbound to m-c uplift this morning, so I guess it didn't make today's Nightly. Pity.

Please let me know if the patch in bug 845966 does not fix the issue.

Comment 4

[Randell Jesup [:jesup] (needinfo me)]

Verified dup.

Thanks for solving it.  I was afraid it had something to do with MediaStreams, though I had no freaking idea how....  Still weird that creating (and destroying) a mediaStream caused it to hang 100% of the time on shutdown, but only if I did that (apparently).

Comment 5

[Gregory Szorc [:gps]]

(In reply to Randell Jesup [:jesup] from comment #4)
> Verified dup.
> 
> Thanks for solving it.  I was afraid it had something to do with
> MediaStreams, though I had no freaking idea how....  Still weird that
> creating (and destroying) a mediaStream caused it to hang 100% of the time
> on shutdown, but only if I did that (apparently).

To be clear, FHR got in a bad state on startup and this caused FHR to hang on shutdown since it was waiting for an event that would never finish.

Your use of MediaStreams is probably just a coincidence or was the tipping point for pushing the stack over the limit.