Add support for dumping GC heap snapshots of Workers

https://bugs.webkit.org/show_bug.cgi?id=269853
rdar://123390121

Reviewed by Simon Fraser.

This will help us understand memory usuage for Workers.

* Source/WebCore/bindings/js/GCController.cpp:
(WebCore::GCController::dumpHeapForVM):
(WebCore::GCController::dumpHeap):
* Source/WebCore/bindings/js/GCController.h:
* Source/WebCore/workers/WorkerGlobalScope.cpp:
(WebCore::WorkerGlobalScope::dumpGCHeapForWorkers):
* Source/WebCore/workers/WorkerGlobalScope.h:

Canonical link: https://commits.webkit.org/275242@main

Source/WebCore/bindings/js/GCController.cpp

@@ -29,6 +29,7 @@
 #include "CommonVM.h"
 #include "JSHTMLDocument.h"
 #include "Location.h"
+#include "WorkerGlobalScope.h"
 #include <JavaScriptCore/Heap.h>
 #include <JavaScriptCore/HeapSnapshotBuilder.h>
 #include <JavaScriptCore/JSLock.h>
@@ -138,7 +139,7 @@ void GCController::deleteAllLinkedCode(DeleteAllCodeEffort effort)
     commonVM().deleteAllLinkedCode(effort);
 }
 
-void GCController::dumpHeap()
+void GCController::dumpHeapForVM(VM& vm)
 {
     FileSystem::PlatformFileHandle fileHandle;
     String tempFilePath = FileSystem::openTemporaryFile("GCHeap"_s, fileHandle);
@@ -147,9 +148,7 @@ void GCController::dumpHeap()
         return;
     }
 
-    VM& vm = commonVM();
     JSLockHolder lock(vm);
-
     sanitizeStackForVM(vm);
 
     String jsonData;
@@ -166,8 +165,13 @@ void GCController::dumpHeap()
 
     FileSystem::writeToFile(fileHandle, utf8String.data(), utf8String.length());
     FileSystem::closeFile(fileHandle);
-
-    WTFLogAlways("Dumped GC heap to %s", tempFilePath.utf8().data());
+    WTFLogAlways("Dumped GC heap to %s%s", tempFilePath.utf8().data(), isMainThread() ? ""_s : " for Worker");
+}
+
+void GCController::dumpHeap()
+{
+    dumpHeapForVM(commonVM());
+    WorkerGlobalScope::dumpGCHeapForWorkers();
 }
 
 } // namespace WebCore

Source/WebCore/bindings/js/GCController.h

@@ -38,6 +38,7 @@ class GCController {
     friend class WTF::NeverDestroyed<GCController>;
 public:
     WEBCORE_EXPORT static GCController& singleton();
+    WEBCORE_EXPORT static void dumpHeapForVM(JSC::VM&);
 
     WEBCORE_EXPORT void garbageCollectSoon();
     WEBCORE_EXPORT void garbageCollectNow(); // It's better to call garbageCollectSoon, unless you have a specific reason not to.

Source/WebCore/workers/WorkerGlobalScope.cpp

@@ -37,6 +37,7 @@
 #include "DocumentInlines.h"
 #include "FontCustomPlatformData.h"
 #include "FontFaceSet.h"
+#include "GCController.h"
 #include "IDBConnectionProxy.h"
 #include "ImageBitmapOptions.h"
 #include "InspectorInstrumentation.h"
@@ -633,6 +634,16 @@ void WorkerGlobalScope::releaseMemoryInWorkers(Synchronous synchronous)
     }
 }
 
+void WorkerGlobalScope::dumpGCHeapForWorkers()
+{
+    Locker locker { allWorkerGlobalScopeIdentifiersLock };
+    for (auto& globalScopeIdentifier : allWorkerGlobalScopeIdentifiers()) {
+        postTaskTo(globalScopeIdentifier, [](auto& context) {
+            GCController::dumpHeapForVM(downcast<WorkerGlobalScope>(context).vm());
+        });
+    }
+}
+
 void WorkerGlobalScope::setMainScriptSourceProvider(ScriptBufferSourceProvider& provider)
 {
     ASSERT(!m_mainScriptSourceProvider);

Source/WebCore/workers/WorkerGlobalScope.h

@@ -163,6 +163,7 @@ class WorkerGlobalScope : public Supplementable<WorkerGlobalScope>, public Base6
 
     void releaseMemory(Synchronous);
     static void releaseMemoryInWorkers(Synchronous);
+    static void dumpGCHeapForWorkers();
 
     void setMainScriptSourceProvider(ScriptBufferSourceProvider&);
     void addImportedScriptSourceProvider(const URL&, ScriptBufferSourceProvider&);