Bug 53100 – WK2 leaks when a page is closed

• Component: Accessibility
• Status: RESOLVED FIXED

[chris fleizach]

It looks like the remote accessibility element holds strong references to the window object. 
To remedy, WKView should release those references when the page closes.

<rdar://problem/8868239>

[chris fleizach]

Created attachment 80084 [details]
Patch

[Build Bot]

Attachment 80084 [details] did not build on win:
Build output: http://queues.webkit.org/results/7582371

[chris fleizach]

Created attachment 80088 [details]
Patch

[Early Warning System Bot]

Attachment 80084 [details] did not build on qt:
Build output: http://queues.webkit.org/results/7516293

[Sam Weinig]

Comment on attachment 80084 [details]
Patch

This needs to stub out pageClosed in the other PageClients (win/WebView.h, API/qt/qwkpage_p.h). We may also want to do this when the process crashes.

[Early Warning System Bot]

Attachment 80088 [details] did not build on qt:
Build output: http://queues.webkit.org/results/7614333

[Darin Adler]

Comment on attachment 80088 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=80088&action=review

Please don’t break the Qt build, otherwise looks good.

> Source/WebKit2/UIProcess/API/mac/WKView.mm:1405
> +    WKAXInitializeRemoteElementWithWindow(_data->_remoteAccessibilityChild.get(), nil);

The use of initialize in the name of this function makes it surprising that you can use it to clear the window. Perhaps it should be called WKAXSetWindowForRemoteElement?

> Source/WebKit2/UIProcess/win/WebView.cpp:631
> +void WebView::pageClosed()
> +{
> +}

I think you’ll need this for Qt too, in UIProcess/API/qt/qwkpage.cpp.

[chris fleizach]

> The use of initialize in the name of this function makes it surprising that you can use it to clear the window. Perhaps it should be called WKAXSetWindowForRemoteElement?
> 

file https://bugs.webkit.org/show_bug.cgi?id=53118 to handle the rename

[Anders Carlsson]

(In reply to comment #9)
> > The use of initialize in the name of this function makes it surprising that you can use it to clear the window. Perhaps it should be called WKAXSetWindowForRemoteElement?
> > 
> 
> file https://bugs.webkit.org/show_bug.cgi?id=53118 to handle the rename

Instead of doing this in close, could we do it in viewDidMoveToWindow when the new window is nil?

That way you wouldn't always leak the WKView unless you explicitly call close.

[chris fleizach]

(In reply to comment #10)
> (In reply to comment #9)
> > > The use of initialize in the name of this function makes it surprising that you can use it to clear the window. Perhaps it should be called WKAXSetWindowForRemoteElement?
> > > 
> > 
> > file https://bugs.webkit.org/show_bug.cgi?id=53118 to handle the rename
> 
> Instead of doing this in close, could we do it in viewDidMoveToWindow when the new window is nil?
> 
> That way you wouldn't always leak the WKView unless you explicitly call close.

It looks like viewDidMoveToWindow is not called when the window is closed

[chris fleizach]

Created attachment 80110 [details]
Patch

[Darin Adler]

Comment on attachment 80110 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=80110&action=review

This patch failed to apply because of a merge conflict, so we are not getting EWS results for it. You probably should merge and post a new patch so we can see if it breaks the build or not.

> Source/WebKit2/UIProcess/API/mac/WKView.mm:1412
> +    [self _setRemoteAccessibilityWindow:nil];

We may want to do this in viewDidMoveToWindow as well, as Anders suggested, even though we can’t do it only there.

[chris fleizach]

Created attachment 80126 [details]
Patch

[chris fleizach]

adding patch to see if it builds on qt

[chris fleizach]

http://trac.webkit.org/changeset/76657

[chris fleizach]

Comment on attachment 80126 [details]
Patch

already reviewed by darin