Bug 149761 – Event queue for WebView on El Capitan with WebKit 601.1.56 breaks with GPU rendering

• Status: NEW
• Component: WebKit API

[Omar Kilani]

Hey WebKit team,

We're seeing a weird issue (seems related to El Capitan?) where if we force GPU rendering of a layer with '-webkit-transform: translateZ(0)' anywhere on a page, the page stops all events (no hover events, no timer events, etc) until we move the mouse or after a couple of second delay.

Safari 9 is unaffected, but WebView embedded into our own wrapper app breaks.

If we remove the '-webkit-transform' everything works as expected, but the bugs we're working around using '-webkit-transform' come back (weird issues with Apple's WebKit + requestAnimationFrame and our web app).

WebView under Yosemite wasn't affected. I don't know if there's some BOOL that needs to be set to make this work, or if I've missed some power saving thing in El Capitan that stops delivering events to our app.

I'm not sure how to repro this except by providing the app itself, so please let me know if that would be helpful (it's just a wrapper around a web app using MacGap2).

Thanks!

Omar

[Alexey Proskuryakov]

Yes, please do provide a reproducible test case.

[Simon Fraser (smfr)]

If you want to provide the app in a private forum, please file a bug at bugreport.apple.com and attach it.

[Omar Kilani]

I've filed a radar:

rdar://22961195

With the source code and a screencast attached.

Hope that helps...

Please let me know if you need anything else.

[Omar Kilani]

FWIW, we were able to work around this by using WKWebView instead of WebView on 10.11.

[Simon Fraser (smfr)]

I took a look, and the title is a bit misleading. It's actually just failing to repaint a layer after content changes, specifically the background color transitions on the rows. I'm not sure why that happens yet.

[Omar Kilani]

(In reply to comment #5)
> I took a look, and the title is a bit misleading. It's actually just failing
> to repaint a layer after content changes, specifically the background color
> transitions on the rows. I'm not sure why that happens yet.

Hi Simon,

That's not what I'm seeing...

I don't know if you have access to the .mov I uploaded to Radar, but the entire JS engine freezes until I move the mouse (clicking the nav items on the left nav doesn't update the list on the right until I move the mouse [or a background XHR completes?]).

WKWebView seems to be using the multi process renderer, but no idea why that makes a difference in this case.

There's a lot of code in the uploaded sample, but you can just stick a WebView into a view controller and the same thing happens (and we've had users complaining that Fluid.app "hangs" after upgrading to El Capitan, etc, etc).

WKWebView works for us as a work around since it seems faster anyway, but I don't understand the reason for what's happening, and thought it might be worth investigating/fixing.