Bug 234328 – Twitter scroll stutter: ensure that CA backing store is always deallocated on the main thread

• Component: Scrolling
• Status: RESOLVED FIXED

[Simon Fraser (smfr)]

Twitter scroll stutter: ensure that CA backing store is always deallocated on the main thread

[Simon Fraser (smfr)]

Created attachment 447186 [details]
Patch

[Simon Fraser (smfr)]

<rdar://problem/85892959>

[Tim Horton]

Comment on attachment 447186 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=447186&action=review

Not the least frightening patch I've ever seen.

> Source/WebCore/WebCore.xcodeproj/project.pbxproj:-33104
> -				7B582DD82716F55B004B92D0 /* (null) in Headers */,

This seems bad

> Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.mm:82
> +            RunLoop::main().dispatch([] {

Isn't it the scrolling thread runloop you're racing here (freeing the transaction), not the main thread?

[Simon Fraser (smfr)]

Comment on attachment 447186 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=447186&action=review

>> Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerContentsDelayedReleaser.mm:82
>> +            RunLoop::main().dispatch([] {
> 
> Isn't it the scrolling thread runloop you're racing here (freeing the transaction), not the main thread?

Probably, but we know we've exited the scrolling thread transaction (tho it may still be in the teardown phase), and we have a dispatch here so it should almost always win. I never saw us lose the race in practice. If we do, it's not the end of the world.

[Simon Fraser (smfr)]

Created attachment 447201 [details]
Patch

[EWS]

Committed r287079 (?): <https://commits.webkit.org/r287079>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 447201 [details].