916387 - ScriptProcessorNode stops calling onaudioprocess when a connected input is GCed.

Status: RESOLVED FIXED

(Core :: Web Audio, defect, P2)

Description

[Karl Tomlinson (:karlt)]

Attachment: script-processor-2.html

Load testcase, then click "Minimize memory usage" in about:memory.

http://lists.w3.org/Archives/Public/public-audio/2013JulSep/1824.html
"
> If an AudioNode connected to the ScriptProcessorNode is deleted
> because it has no references, then the ScriptProcessNode will stop
> firing onaudioprocess at the time when the connected node is deleted.

I don't think so. In this case, the observable behavior that must be
preserved is that the AudioNode is connected and the ScriptProcessorNode
keeps dispatching onaudioprocess. Automatic removal of the AudioNode can
only be done insofar as we preserve that observable behavior. In other
words, the onaudioprocess event must keep firing."

http://lists.w3.org/Archives/Public/public-audio/2013JulSep/1835.html
"
> I don't really see how you can fix it in this case other than by making an
> AudioNode + ScriptProcessorNode pair an uncollectable cycle that leaks
> forever if you release it.

That's what we do."

We can collect the AudioNode, but we'd have to tell the ScriptProcessorNode that it has an input that will never be removed (because there are no references to the input).

Comment 1

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Yes.

Comment 2

[Karl Tomlinson (:karlt)]

Attachment: add a notification of garbage collected input node

The effects of garbage collection must not be observable.  We can collect an
AudioNode if it is not going to cause any further changes, but we must keep
any current effects.

Comment 3

[Karl Tomlinson (:karlt)]

Attachment: keep ScriptProcessorNode alive after input is GCed

Comment 4

[Karl Tomlinson (:karlt)]

Attachment: remove workarounds in tests

Zero output channels are used on ScriptProcessorNodes to improve efficiency in
tests when output is not required.

Comment 5

[Karl Tomlinson (:karlt)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=9807ec6525ef
https://treeherder.mozilla.org/#/jobs?repo=try&revision=d73baba7b76f

Comment 6

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/b2852b6ae7db
https://hg.mozilla.org/integration/mozilla-inbound/rev/4dd0bec5365b
https://hg.mozilla.org/integration/mozilla-inbound/rev/ef89d3dfb137

Comment 7

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/b2852b6ae7db
https://hg.mozilla.org/mozilla-central/rev/4dd0bec5365b
https://hg.mozilla.org/mozilla-central/rev/ef89d3dfb137