[Webkit-unassigned] [Bug 135331] New: Web Audio doesn't release audio resources when nodes disconnected

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=135331

           Summary: Web Audio doesn't release audio resources when nodes
                    disconnected
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Macintosh Intel
               URL: https://brionv.com/misc/audio-test.html
        OS/Version: Mac OS X 10.9
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Web Audio
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: brion at wikimedia.org
                CC: crogers at google.com


Creation of a Web Audio context and source node (for instance an oscillator or a JavaScriptNode) seems to cause Safari/WebKit to use audio resources for the duration of the page lifetime, even after the node has been disconnected and the context and node variables nulled out for possible garbage collection.

This causes a moderate CPU usage increase in coreaudiod on OS X or mediaserverd on iOS, which doesn't go away until the page is closed, reloaded, or otherwise navigated away from. For a long-running web app that uses audio only intermittently, this may cause unnecessary battery drain etc.

Steps to reproduce:
* Open Activity Monitor or other process monitor to watch for CPU usage
* Open WebKit nightly or Safari 7 to https://brionv.com/misc/audio-test.html
* Click 'Start audio' (it will be silent)
* Click 'Stop audio'

The CPU usage of coreaudiod (OS X) or mediaserverd (iOS) goes up a few percentage points at start, but doesn't go down at stop. Only when the page is unloaded are the resources being released.

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