Bug 71196 – [Qt] [WK2] MiniBrowser assert in QtWebProccess on startup in debug build.

• Component: New Bugs
• Status: RESOLVED FIXED

[Viatcheslav Ostapenko]

Assert in DrawingAreaImpl::exitAcceleratedCompositingMode()

ASSERT(!m_layerTreeStateIsFrozen);

Call stack:
0	WebKit::DrawingAreaImpl::exitAcceleratedCompositingMode	DrawingAreaImpl.cpp	470	0xb5fd7ad4	
1	WebKit::DrawingAreaImpl::setRootCompositingLayer	DrawingAreaImpl.cpp	298	0xb5fd7111	
2	WebKit::WebPage::exitAcceleratedCompositingMode	WebPage.cpp	468	0xb5ed1396	
3	WebKit::WebChromeClient::attachRootGraphicsLayer	WebChromeClient.cpp	684	0xb5fb8aff	
4	WebCore::RenderLayerCompositor::detachRootLayer	RenderLayerCompositor.cpp	1899	0xb66dcc37	
5	WebCore::RenderLayerCompositor::destroyRootLayer	RenderLayerCompositor.cpp	1808	0xb66dc63c	
6	WebCore::RenderLayerCompositor::enableCompositingMode	RenderLayerCompositor.cpp	129	0xb66d6eb0	
7	WebCore::RenderLayerCompositor::computeCompositingRequirements	RenderLayerCompositor.cpp	791	0xb66d9198	
8	WebCore::RenderLayerCompositor::updateCompositingLayers	RenderLayerCompositor.cpp	304	0xb66d7626	
9	WebCore::FrameView::updateCompositingLayers	FrameView.cpp	643	0xb650eac8	
10	WebCore::FrameView::layout	FrameView.cpp	1127	0xb650ffb0	
11	WebCore::FrameView::visibleContentsResized	FrameView.cpp	1802	0xb65124be	
12	WebCore::ScrollView::updateScrollbars	ScrollView.cpp	516	0xb65c6168	
13	WebCore::ScrollView::setFrameRect	ScrollView.cpp	863	0xb65c7a32	
14	WebCore::FrameView::setFrameRect	FrameView.cpp	406	0xb650df67	
15	WebCore::Widget::resize	Widget.h	143	0xb5d7d9d6	
16	WebKit::WebPage::setSize	WebPage.cpp	687	0xb5ed2917	
17	WebKit::DrawingAreaImpl::updateBackingStoreState	DrawingAreaImpl.cpp	328	0xb5fd72ac	
18	CoreIPC::callMemberFunction<WebKit::DrawingArea, void (WebKit::DrawingArea::*)(unsigned long long, bool, float, WebCore::IntSize const&, WebCore::IntSize const&), unsigned long long, bool, float, WebCore::IntSize, WebCore::IntSize>	HandleMessage.h	43	0xb5efa40e	
19	CoreIPC::handleMessage<Messages::DrawingArea::UpdateBackingStoreState, WebKit::DrawingArea, void (WebKit::DrawingArea::*)(unsigned long long, bool, float, WebCore::IntSize const&, WebCore::IntSize const&)>	HandleMessage.h	277	0xb5efa059	
20	WebKit::DrawingArea::didReceiveDrawingAreaMessage	DrawingAreaMessageReceiver.cpp	47	0xb5ef9db6	
21	WebKit::WebPage::didReceiveMessage	WebPage.cpp	2205	0xb5ed856c	
22	WebKit::WebProcess::didReceiveMessage	WebProcess.cpp	658	0xb5eea5a1	
23	CoreIPC::Connection::dispatchMessage	Connection.cpp	689	0xb5f1ed76	
24	CoreIPC::Connection::dispatchMessages	Connection.cpp	716	0xb5f1ef1f	
25	MemberFunctionWorkItem0<CoreIPC::Connection>::execute	WorkItem.h	79	0xb5f276af	
26	RunLoop::performWork	RunLoop.cpp	63	0xb5e04499	
27	RunLoop::TimerObject::performWork	RunLoopQt.cpp	49	0xb5e0549c	
28	RunLoop::TimerObject::qt_static_metacall	RunLoopQt.moc	48	0xb5e05eca	
29	QMetaCallEvent::placeMetaCall	qobject.cpp	529	0xb284d6d6	
30	QObject::event	qobject.cpp	1111	0xb284e2f7	
31	QApplicationPrivate::notify_helper	qapplication.cpp	4080	0xb35dc436	
32	QApplication::notify	qapplication.cpp	3497	0xb35d9e37	
33	QCoreApplication::notifyInternal	qcoreapplication.cpp	827	0xb282e10a	
34	QCoreApplication::sendEvent	qcoreapplication.h	205	0xb5d78a35	
35	QCoreApplicationPrivate::sendPostedEvents	qcoreapplication.cpp	1469	0xb282efef	
36	QCoreApplication::sendPostedEvents	qcoreapplication.cpp	1339	0xb282ecab	
37	QCoreApplication::sendPostedEvents	qcoreapplication.h	210	0xb2b3564a	
38	QWindowSystemInterface::sendWindowSystemEvents	qwindowsysteminterface_qpa.cpp	296	0xb2b3542a	
39	QEventDispatcherQPA::processEvents	qeventdispatcher_qpa.cpp	70	0xb09550e8	
40	QEventLoop::processEvents	qeventloop.cpp	149	0xb282bc31	
41	QEventLoop::exec	qeventloop.cpp	225	0xb282be92	
42	QCoreApplication::exec	qcoreapplication.cpp	1094	0xb282e76e	
43	RunLoop::run	RunLoopQt.cpp	65	0xb5e056c9	
44	WebKit::WebProcessMainQt	WebProcessMainQt.cpp	199	0xb5e00e6f	
45	main	MainQt.cpp	38	0x804850f

[Viatcheslav Ostapenko]

Created attachment 113004 [details]
Delay exit from AC mode if layer state is frozen during setSize/layout.

[Simon Hausmann]

Comment on attachment 113004 [details]
Delay exit from AC mode if layer state is frozen during setSize/layout.

View in context: https://bugs.webkit.org/attachment.cgi?id=113004&action=review

> Source/WebKit2/WebProcess/WebPage/DrawingAreaImpl.cpp:297
> +                if (m_inUpdateBackingStoreState && !m_layerTreeStateIsFrozen)

How is it possible to hit this code patch? It's wrapped in if (!m_alwaysUseCompositing).

[Simon Hausmann]

As a matter of fact, I can't reproduce this on trunk (r98839), because we should now always be compositing.

[Viatcheslav Ostapenko]

(In reply to comment #3)
> As a matter of fact, I can't reproduce this on trunk (r98839), because we should now always be compositing.

I have r98793 and it doesn't run in AC always mode.
I'll figure out.

[Viatcheslav Ostapenko]

(In reply to comment #3)
> As a matter of fact, I can't reproduce this on trunk (r98839), because we should now always be compositing.

It's QDesktopWebView.Seems QDesktopWebView doesn't have AC because QtDesktopWebPageProxy disables AC in constructor:

[Noam Rosenthal]

Maybe a better solution would be to expose forceCompositing to WebPreferencesPrivate, and to enable force-compositing for touch only.

[Simon Hausmann]

Ohh, I see.

On that note: Alexis is currently working on changing the DesktopWebView from a painted item to using AC together with layered scrollbars.

[Viatcheslav Ostapenko]

(In reply to comment #6)
> Maybe a better solution would be to expose forceCompositing to WebPreferencesPrivate, and to enable force-compositing for touch only.

forceCompositing is not enabled for desktop view. The problem, that it tries to switch AC on and off. IMHO, another solution would be to disable AC for DV now.

[Viatcheslav Ostapenko]

(In reply to comment #6)
> Maybe a better solution would be to expose forceCompositing to WebPreferencesPrivate, and to enable force-compositing for touch only.

BTW, is any other port still using switchable AC (not always on)?
In this case they would need patch because webprocess would assert/crash if window get resized during load (when m_layerTreeStateIsFrozen is set).
In Qt Minibrowser on startup 1st comes load, then setSize from window getting visible.

[Noam Rosenthal]

(In reply to comment #9)
> (In reply to comment #6)
> > Maybe a better solution would be to expose forceCompositing to WebPreferencesPrivate, and to enable force-compositing for touch only.
> 
> BTW, is any other port still using switchable AC (not always on)?
> In this case they would need patch because webprocess would assert/crash if window get resized during load (when m_layerTreeStateIsFrozen is set).
> In Qt Minibrowser on startup 1st comes load, then setSize from window getting visible.

Yes, Apple uses switchable AC I believe. but we have AC always on for touch and always off for desktop (at least that's how it should be).

[Simon Hausmann]

(In reply to comment #10)
> (In reply to comment #9)
> > (In reply to comment #6)
> > > Maybe a better solution would be to expose forceCompositing to WebPreferencesPrivate, and to enable force-compositing for touch only.
> > 
> > BTW, is any other port still using switchable AC (not always on)?
> > In this case they would need patch because webprocess would assert/crash if window get resized during load (when m_layerTreeStateIsFrozen is set).
> > In Qt Minibrowser on startup 1st comes load, then setSize from window getting visible.
> 
> Yes, Apple uses switchable AC I believe. but we have AC always on for touch and always off for desktop (at least that's how it should be).

And it turns out that this is where the bug is, AC is not actually properly turned off for the desktop view. I'm fixing this as we speak :)

[Simon Hausmann]

Created attachment 113449 [details]
[Qt] [WK2] MiniBrowser assert in QtWebProccess on startup in debug build.

[Simon Hausmann]

Comment on attachment 113449 [details]
[Qt] [WK2] MiniBrowser assert in QtWebProccess on startup in debug build.

Clearing flags on attachment: 113449

Committed r99165: <http://trac.webkit.org/changeset/99165>

[Simon Hausmann]

All reviewed patches have been landed.  Closing bug.