Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 9d9aae7cdf45509e1db82e3ae563cbd650508fee
https://github.com/WebKit/WebKit/commit/9d9aae7cdf45509e1db82e3ae563cbd650508fee
Author: Yusuke Suzuki <[email protected]>
Date: 2026-02-20 (Fri, 20 Feb 2026)
Changed paths:
M Source/JavaScriptCore/CMakeLists.txt
M Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj
M Source/JavaScriptCore/Sources.txt
M Source/JavaScriptCore/heap/Heap.cpp
M Source/JavaScriptCore/heap/Heap.h
M Source/JavaScriptCore/runtime/JSGlobalObject.cpp
M Source/JavaScriptCore/runtime/JSGlobalObject.h
A Source/JavaScriptCore/runtime/JSMicrotaskDispatcher.cpp
A Source/JavaScriptCore/runtime/JSMicrotaskDispatcher.h
M Source/JavaScriptCore/runtime/JSType.cpp
M Source/JavaScriptCore/runtime/JSType.h
M Source/JavaScriptCore/runtime/Microtask.h
M Source/JavaScriptCore/runtime/MicrotaskQueue.cpp
M Source/JavaScriptCore/runtime/MicrotaskQueue.h
M Source/JavaScriptCore/runtime/MicrotaskQueueInlines.h
M Source/JavaScriptCore/runtime/VM.cpp
M Source/JavaScriptCore/runtime/VM.h
M Source/WebCore/bindings/js/JSDOMWindowBase.cpp
M Source/WebCore/bindings/js/JSWorkerGlobalScopeBase.cpp
M Source/WebCore/bindings/js/ScriptController.cpp
M Source/WebCore/dom/Document.cpp
M Source/WebCore/dom/Document.h
M Source/WebCore/dom/EventLoop.cpp
M Source/WebCore/dom/EventLoop.h
M Source/WebCore/dom/Microtasks.cpp
M Source/WebCore/dom/Microtasks.h
M Source/WebCore/dom/ScriptExecutionContext.cpp
M Source/WebCore/dom/ScriptExecutionContext.h
M Source/WebCore/workers/WorkerOrWorkletGlobalScope.cpp
M Source/WebCore/workers/WorkerOrWorkletGlobalScope.h
M Source/WebCore/workers/WorkerOrWorkletScriptController.cpp
Log Message:
-----------
MicrotaskDispatcher should be JSCell
https://bugs.webkit.org/show_bug.cgi?id=308264
rdar://170765991
Reviewed by Yijia Huang.
Under incredible amount of QueuedTasks, even ref / deref is costly. And
accessing EventLoopTaskGroup's WeakPtr (and involving indirections) is
also costly too.
1. We introduce JSMicrotaskDispatcher JSCell. And use it in QueuedTask
instead of Ref<MicrotaskDispatcher>. This removes ref / deref since
it is no GC managed. MicrotaskQueue visits them correctly (along with
the other JSValues as well).
2. JSMicrotaskDispatcher has inlined fields for the current associated
dispatcher's state (runnability). And EventLoopTaskGroup will update
this proactively instead of pulling information from them. This is
much more efficient: we peek this information for each microtask, but
EventLoopTaskGroup does not update this state so frequently.
3. Since EventLoop is associated with ScriptExecutionContext, and it is
tied to JSGlobalObject, we now store runnability information to
JSGlobalObject, and store JSGlobalObject to dispatcher field for
common cases. Thus we can unify JSMicrotaskDispatcher and
JSGlobalObject field in QueuedTask, which shrinks sizeof(QueuedTask).
This is critical for performance. Note that this patch is 100% aware
that EventLoopTaskGroup v.s. JSGlobalObject is N:1 relationship. We
store this runnability information of the *default*
EventLoopTaskGroup for the JSGlobalObject.
4. We make sure that QueuedTask is now trivially destrucible because we
no longer have Ref<>. Also we ensure that this is now POD and can be
initialized with memset, and even copied with memcpy etc.
5. Also move JSGlobalObject::m_debugger field to the first fields to
make it hit in the cache. m_debugger is frequently accessed to ensure
m_debugger is *not* instantiated.
* Source/JavaScriptCore/CMakeLists.txt:
* Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj:
* Source/JavaScriptCore/Sources.txt:
* Source/JavaScriptCore/heap/Heap.cpp:
* Source/JavaScriptCore/heap/Heap.h:
* Source/JavaScriptCore/runtime/JSGlobalObject.cpp:
(JSC::JSGlobalObject::queueMicrotaskToEventLoop):
* Source/JavaScriptCore/runtime/JSGlobalObject.h:
(JSC::JSGlobalObject::microtaskRunnability const):
(JSC::JSGlobalObject::setMicrotaskRunnability):
* Source/JavaScriptCore/runtime/JSMicrotaskDispatcher.cpp: Added.
(JSC::JSMicrotaskDispatcher::createStructure):
(JSC::JSMicrotaskDispatcher::create):
(JSC::JSMicrotaskDispatcher::JSMicrotaskDispatcher):
(JSC::JSMicrotaskDispatcher::visitChildrenImpl):
(JSC::JSMicrotaskDispatcher::destroy):
* Source/JavaScriptCore/runtime/JSMicrotaskDispatcher.h: Added.
* Source/JavaScriptCore/runtime/JSType.cpp:
(WTF::printInternal):
* Source/JavaScriptCore/runtime/JSType.h:
* Source/JavaScriptCore/runtime/Microtask.h:
* Source/JavaScriptCore/runtime/MicrotaskQueue.cpp:
(JSC::QueuedTask::isRunnable const):
(JSC::MarkedMicrotaskDeque::visitAggregateImpl):
* Source/JavaScriptCore/runtime/MicrotaskQueue.h:
(JSC::QueuedTask::QueuedTask):
(JSC::QueuedTask::setDispatcher):
(JSC::QueuedTask::dispatcher const): Deleted.
(JSC::QueuedTask::identifier const):
(JSC::QueuedTask::globalObject const): Deleted.
* Source/JavaScriptCore/runtime/MicrotaskQueueInlines.h:
(JSC::QueuedTask::dispatcher const):
(JSC::QueuedTask::globalObject const):
(JSC::QueuedTask::jsMicrotaskDispatcher const):
(JSC::QueuedTask::identifier const):
* Source/JavaScriptCore/runtime/VM.cpp:
(JSC::VM::VM):
(JSC::VM::drainMicrotasks):
(JSC::VM::visitAggregateImpl):
* Source/JavaScriptCore/runtime/VM.h:
* Source/WebCore/bindings/js/JSDOMWindowBase.cpp:
(WebCore::JSDOMWindowBase::queueMicrotaskToEventLoop):
* Source/WebCore/bindings/js/JSWorkerGlobalScopeBase.cpp:
(WebCore::JSWorkerGlobalScopeBase::queueMicrotaskToEventLoop):
* Source/WebCore/bindings/js/ScriptController.cpp:
(WebCore::ScriptController::initScriptForWindowProxy):
* Source/WebCore/dom/Document.cpp:
(WebCore::Document::commonTeardown):
(WebCore::Document::isEventLoopGroupStoppedPermanently const):
(WebCore::Document::eventLoop):
* Source/WebCore/dom/Document.h:
* Source/WebCore/dom/EventLoop.cpp:
(WebCore::EventLoopTaskGroup::EventLoopTaskGroup):
(WebCore::EventLoopTaskGroup::jsMicrotaskDispatcherForDebugger):
(WebCore::EventLoopTaskGroup::setScriptExecutionContext):
(WebCore::EventLoopTaskGroup::stopAndDiscardAllTasks):
(WebCore::EventLoopTaskGroup::queueMicrotask):
(WebCore::EventLoopTaskGroup::jsMicrotaskDispatcher):
* Source/WebCore/dom/EventLoop.h:
* Source/WebCore/dom/Microtasks.cpp:
(WebCore::MicrotaskQueue::performMicrotaskCheckpoint):
* Source/WebCore/dom/Microtasks.h:
* Source/WebCore/dom/ScriptExecutionContext.cpp:
(WebCore::ScriptExecutionContext::setMicrotaskGlobalObject):
(WebCore::ScriptExecutionContext::microtaskGlobalObject const):
(WebCore::ScriptExecutionContext::clearMicrotaskGlobalObject):
(WebCore::ScriptExecutionContext::suspendActiveDOMObjects):
(WebCore::ScriptExecutionContext::resumeActiveDOMObjects):
* Source/WebCore/dom/ScriptExecutionContext.h:
(WebCore::ScriptExecutionContext::isEventLoopGroupStoppedPermanently const):
* Source/WebCore/workers/WorkerOrWorkletGlobalScope.cpp:
(WebCore::WorkerOrWorkletGlobalScope::prepareForDestruction):
(WebCore::WorkerOrWorkletGlobalScope::eventLoop):
(WebCore::WorkerOrWorkletGlobalScope::isEventLoopGroupStoppedPermanently const):
* Source/WebCore/workers/WorkerOrWorkletGlobalScope.h:
* Source/WebCore/workers/WorkerOrWorkletScriptController.cpp:
(WebCore::WorkerOrWorkletScriptController::initScriptWithSubclass):
Canonical link: https://commits.webkit.org/307966@main
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