Bug 208780

Summary:	No need to schedule/unschedule style recalcs and layouts inside of a rendering update
Product:	WebKit	Reporter:	Simon Fraser (smfr) <simon.fraser>
Component:	Layout and Rendering	Assignee:	Rob Buis <rbuis>
Status:	NEW ---
Severity:	Normal	CC:	bfulgham, koivisto, rniwa, simon.fraser, zalan
Priority:	P2
Version:	Safari Technology Preview
Hardware:	Unspecified
OS:	Unspecified
See Also:	https://bugs.webkit.org/show_bug.cgi?id=201018 https://bugs.webkit.org/show_bug.cgi?id=201019

Description Simon Fraser (smfr) 2020-03-07 18:15:40 PST

We waste time updating timers during a rendering update:

Style recalc timer:

CFRunLoopTimerSetNextFireDate
WebCore::MainThreadSharedTimer::setFireInterval(WTF::Seconds)
WebCore::ThreadTimers::updateSharedTimer()
WebCore::TimerBase::setNextFireTime(WTF::MonotonicTime)
WebCore::TimerBase::start(WTF::Seconds, WTF::Seconds)
WebCore::TimerBase::startOneShot(WTF::Seconds)
WebCore::Document::scheduleStyleRecalc()
WebCore::Node::updateAncestorsForStyleRecalc()
WebCore::Node::invalidateStyle(WebCore::Style::Validity, WebCore::Style::InvalidationMode)
WebCore::Element::invalidateStyle()
WebCore::StyledElement::invalidateStyleAttribute()
WebCore::InlineCSSStyleDeclaration::didMutate(WebCore::PropertySetCSSStyleDeclaration::MutationType)
WebCore::PropertySetCSSStyleDeclaration::setPropertyInternal(WebCore::CSSPropertyID, WTF::String const&, bool)
WebCore::CSSStyleDeclaration::setNamedItem(WTF::AtomString const&, WTF::String, bool&)
WebCore::JSCSSStyleDeclaration::put(JSC::JSCell*, JSC::JSGlobalObject*, JSC::PropertyName, JSC::JSValue, JSC::PutPropertySlot&)
JSC::JSCell::putInline(JSC::JSGlobalObject*, JSC::PropertyName, JSC::JSValue, JSC::PutPropertySlot&)
JSC::JSValue::putInline(JSC::JSGlobalObject*, JSC::PropertyName, JSC::JSValue, JSC::PutPropertySlot&)
operationPutByIdNonStrict
0x4ed07c0002cd
vmEntryToJavaScript
JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*)
JSC::Interpreter::executeCall(JSC::JSGlobalObject*, JSC::JSObject*, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&)
JSC::call(JSC::JSGlobalObject*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&)
JSC::call(JSC::JSGlobalObject*, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&, WTF::NakedPtr<JSC::Exception>&)
JSC::profiledCall(JSC::JSGlobalObject*, JSC::ProfilingReason, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&, WTF::NakedPtr<JSC::Exception>&)
WebCore::JSExecState::profiledCall(JSC::JSGlobalObject*, JSC::ProfilingReason, JSC::JSValue, JSC::CallType, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&, WTF::NakedPtr<JSC::Exception>&)
WebCore::JSEventListener::handleEvent(WebCore::ScriptExecutionContext&, WebCore::Event&)
WebCore::EventTarget::innerInvokeEventListeners(WebCore::Event&, WTF::Vector<WTF::RefPtr<WebCore::RegisteredEventListener, WTF::DumbPtrTraits<WebCore::RegisteredEventListener> >, 1ul, WTF::CrashOnOverflow, 16ul, WTF::FastMalloc>, WebCore::EventTarget::EventInvokePhase)
WebCore::EventTarget::fireEventListeners(WebCore::Event&, WebCore::EventTarget::EventInvokePhase)
WebCore::WindowEventContext::handleLocalEvents(WebCore::Event&, WebCore::EventTarget::EventInvokePhase) const
WebCore::dispatchEventInDOM(WebCore::Event&, WebCore::EventPath const&)
WebCore::EventDispatcher::dispatchEvent(WebCore::Node&, WebCore::Event&)
WebCore::Node::dispatchEvent(WebCore::Event&)
WebCore::Document::runScrollSteps()
WebCore::Page::updateRendering()::$_13::operator()(WebCore::Document&) const

CFRunLoopTimerSetNextFireDate
WebCore::MainThreadSharedTimer::setFireInterval(WTF::Seconds)
WebCore::ThreadTimers::updateSharedTimer()
WebCore::TimerBase::setNextFireTime(WTF::MonotonicTime)
WebCore::TimerBase::stop()
WebCore::Document::unscheduleStyleRecalc()
WebCore::Document::resolveStyle(WebCore::Document::ResolveStyleType)
WebCore::Document::updateStyleIfNeeded()
WebCore::FrameView::updateLayoutAndStyleIfNeededRecursive()
WebCore::Page::layoutIfNeeded()
WebCore::Page::updateRendering()
WebKit::WebPage::updateRendering()


Layout timer:

WebCore::MainThreadSharedTimer::setFireInterval(WTF::Seconds)
WebCore::ThreadTimers::updateSharedTimer()
WebCore::TimerBase::setNextFireTime(WTF::MonotonicTime)
WebCore::TimerBase::start(WTF::Seconds, WTF::Seconds)
WebCore::TimerBase::startOneShot(WTF::Seconds)
WebCore::FrameViewLayoutContext::scheduleLayout()
WebCore::scheduleRelayoutForSubtree(WebCore::RenderElement&)
WebCore::RenderObject::markContainingBlocksForLayout(WebCore::ScheduleRelayout, WebCore::RenderElement*)
WebCore::RenderElement::setNeedsPositionedMovementLayout(WebCore::RenderStyle const*)
WebCore::RenderElement::styleDidChange(WebCore::StyleDifference, WebCore::RenderStyle const*)
WebCore::RenderLayerModelObject::styleDidChange(WebCore::StyleDifference, WebCore::RenderStyle const*)
WebCore::RenderBox::styleDidChange(WebCore::StyleDifference, WebCore::RenderStyle const*)
WebCore::RenderBlock::styleDidChange(WebCore::StyleDifference, WebCore::RenderStyle const*)
WebCore::RenderBlockFlow::styleDidChange(WebCore::StyleDifference, WebCore::RenderStyle const*)
WebCore::RenderElement::setStyle(WebCore::RenderStyle&&, WebCore::StyleDifference)
WebCore::RenderTreeUpdater::updateRendererStyle(WebCore::RenderElement&, WebCore::RenderStyle&&, WebCore::StyleDifference)

WebCore::TimerBase::stop()
WebCore::FrameViewLayoutContext::layout()
WebCore::FrameView::updateLayoutAndStyleIfNeededRecursive()
WebCore::Page::layoutIfNeeded()
WebCore::Page::updateRendering()
WebKit::WebPage::updateRendering()


Scrolling tree commit timer:
WebCore::TimerBase::start(WTF::Seconds, WTF::Seconds)
WebCore::TimerBase::startOneShot(WTF::Seconds)
WebCore::ScrollingCoordinatorMac::scheduleTreeStateCommit()
WebCore::AsyncScrollingCoordinator::scrollingStateTreePropertiesChanged()
WebCore::ScrollingStateTree::setHasChangedProperties(bool)
WebCore::ScrollingStateNode::setPropertyChanged(unsigned int)
WebCore::ScrollingStateScrollingNode::setScrollPosition(WebCore::FloatPoint const&)
WebCore::AsyncScrollingCoordinator::setScrollingNodeScrollableAreaGeometry(unsigned long long, WebCore::ScrollableArea&)
WebCore::RenderLayerCompositor::updateScrollingNodeForScrollingRole(WebCore::RenderLayer&, WebCore::ScrollingTreeState&, WTF::OptionSet<WebCore::RenderLayerCompositor::ScrollingNodeChangeFlags>)
WebCore::RenderLayerCompositor::updateScrollCoordinationForLayer(WebCore::RenderLayer&, WebCore::RenderLayer const*, WebCore::ScrollingTreeState&, WTF::OptionSet<WebCore::RenderLayerCompositor::ScrollingNodeChangeFlags>)
WebCore::RenderLayerCompositor::updateBackingAndHierarchy(WebCore::RenderLayer&, WTF::Vector<WTF::Ref<WebCore::GraphicsLayer, WTF::DumbPtrTraits<WebCore::GraphicsLayer> >, 0ul, WTF::CrashOnOverflow, 16ul, WTF::FastMalloc>&, WebCore::RenderLayerCompositor::UpdateBackingTraversalState&, WebCore::ScrollingTreeState&, WTF::OptionSet<WebCore::RenderLayerCompositor::UpdateLevel>)
WebCore::RenderLayerCompositor::updateCompositingLayers(WebCore::CompositingUpdateType, WebCore::RenderLayer*)
WebCore::FrameView::updateCompositingLayersAfterLayout()
WebCore::FrameView::didLayout(WTF::WeakPtr<WebCore::RenderElement>)
WebCore::FrameViewLayoutContext::layout()
WebCore::FrameView::updateLayoutAndStyleIfNeededRecursive()
WebCore::Page::layoutIfNeeded()
WebCore::Page::updateRendering()
WebKit::WebPage::updateRendering()

None of these are necessary.

Comment 1 Ryosuke Niwa 2020-03-10 23:01:04 PDT

Should we add some flag on Document to indicate that we're in the middle of rendering update?

Comment 2 Ryosuke Niwa 2020-03-10 23:01:58 PDT

Also, in theory, we should never have to schedule style recalc / layout anymore directly.

Comment 3 Rob Buis 2023-07-29 11:20:36 PDT

Pull request: https://github.com/WebKit/WebKit/pull/16213

Comment 4 Rob Buis 2023-07-31 08:48:14 PDT

I think the scheduleLayout case is not happening anymore, at least I could not reproduce it.