Shut down all threads before the main thread shuts down

third_party/WebKit/Source/web/WebKit.cpp

Index: third_party/WebKit/Source/web/WebKit.cpp
diff --git a/third_party/WebKit/Source/web/WebKit.cpp b/third_party/WebKit/Source/web/WebKit.cpp
index 4a4e0acd9a6215966422c5a75f13314917489b4a..0b34d329fe1731ff74d23c781dd3704634a42e34 100644
--- a/third_party/WebKit/Source/web/WebKit.cpp
+++ b/third_party/WebKit/Source/web/WebKit.cpp
@@ -141,6 +141,12 @@ static void adjustAmountOfExternalAllocatedMemory(int size)
     v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(size);
 }
 
+static ModulesInitializer& modulesInitializer()
+{
+    DEFINE_STATIC_LOCAL(OwnPtr<ModulesInitializer>, initializer, (adoptPtr(new ModulesInitializer)));
+    return *initializer;
+}
+
 void initializeWithoutV8(Platform* platform)
 {
     ASSERT(!s_webKitInitialized);
@@ -161,8 +167,7 @@ void initializeWithoutV8(Platform* platform)
         s_gcTaskRunner = new GCTaskRunner(currentThread);
     }
 
-    DEFINE_STATIC_LOCAL(ModulesInitializer, initializer, ());
-    initializer.init();
+    modulesInitializer().init();
 
     setIndexedDBClientCreateFunction(IndexedDBClientImpl::create);
 }
@@ -194,27 +199,17 @@ void shutdown()
         // the shutdown() is called.
         delete s_endOfTaskRunner;
         s_endOfTaskRunner = nullptr;
-
-        ASSERT(s_gcTaskRunner);
-        delete s_gcTaskRunner;
-        s_gcTaskRunner = nullptr;
     }
 
     // Shutdown V8-related background threads before V8 is ramped down. Note
     // that this will wait the thread to stop its operations.
     ScriptStreamerThread::shutdown();
 
+    ThreadState::current()->unregisterTraceDOMWrappers();

[sof, 2016/03/07 07:29:28]

Why is this needed now & here? (sorry, haven't followed the patchset updates
here.)

[haraken, 2016/03/07 07:33:56]

ThreadState::detachMainThread can trigger an Oilpan's GC. The Oilpan GC should
not trace V8 wrappers because the isolate is already existed at that point. Also
the Oilpan GC should assume that no V8 wrappers are reachable at that point. So
I added unregisterTraceDOMWrapper here to let Oilpan know about it before the
isolate gets destroyed.

[sof, 2016/03/07 07:54:03]

I see, and this "detach" of v8 from Oilpan needs to be handled separately from
detachMainThread(). Can detachMainThread() assert that the v8 detach has
happened?

[haraken, 2016/03/07 08:02:34]

Done.

+
     v8::Isolate* isolate = V8PerIsolateData::mainThreadIsolate();
     V8PerIsolateData::willBeDestroyed(isolate);
 
-    CoreInitializer::terminateThreads();
-
-    ModulesInitializer::terminateThreads();
-
-    // Detach the main thread before starting the shutdown sequence
-    // so that the main thread won't get involved in a GC during the shutdown.
-    ThreadState::detachMainThread();
-
     V8PerIsolateData::destroy(isolate);
 
     shutdownWithoutV8();
@@ -222,8 +217,21 @@ void shutdown()
 
 void shutdownWithoutV8()
 {
+    ASSERT(isMainThread());
+    modulesInitializer().shutdown();
+
+    // currentThread() is null if we are running on a thread without a message loop.
+    if (Platform::current()->currentThread()) {
+        ASSERT(s_gcTaskRunner);
+        delete s_gcTaskRunner;
+        s_gcTaskRunner = nullptr;
+    }
+
+    // Detach the main thread before starting the shutdown sequence
+    // so that the main thread won't get involved in a GC during the shutdown.
+    ThreadState::detachMainThread();
+
     ASSERT(!s_endOfTaskRunner);
-    CoreInitializer::shutdown();
     Heap::shutdown();
     WTF::shutdown();
     Platform::shutdown();