Shut down all threads before the main thread shuts down

third_party/WebKit/Source/web/WebKit.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 78 matching lines @@
 static GCTaskRunner* s_gcTaskRunner = nullptr;
 
 // Make sure we are not re-initialized in the same address space.
 // Doing so may cause hard to reproduce crashes.
 static bool s_webKitInitialized = false;
 
 void initialize(Platform* platform)
 {
     initializeWithoutV8(platform);
 
     V8Initializer::initializeMainThreadIfNeeded();

[haraken, 2016/03/03 12:08:46]

This should be renamed to V8Initializer::initializeMainThread. I'll do that in a
follow up.

 
     OwnPtr<V8IsolateInterruptor> interruptor = adoptPtr(new V8IsolateInterruptor(V8PerIsolateData::mainThreadIsolate()));
     ThreadState::current()->addInterruptor(interruptor.release());
     ThreadState::current()->registerTraceDOMWrappers(V8PerIsolateData::mainThreadIsolate(), V8GCController::traceDOMWrappers);
 
     // currentThread is null if we are running on a thread without a message loop.
     if (WebThread* currentThread = platform->currentThread()) {
         ASSERT(!s_endOfTaskRunner);
         s_endOfTaskRunner = new EndOfTaskRunner;
         currentThread->addTaskObserver(s_endOfTaskRunner);
@@ skipping 24 matching lines @@
 static void callOnMainThreadFunction(WTF::MainThreadFunction function, void* context)
 {
     Platform::current()->mainThread()->getWebTaskRunner()->postTask(BLINK_FROM_HERE, threadSafeBind(function, AllowCrossThreadAccess(context)));
 }
 
 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);
     s_webKitInitialized = true;
 
     WTF::Partitions::initialize(maxObservedSizeFunction);
     ASSERT(platform);
     Platform::initialize(platform);
 
     WTF::initialize(adjustAmountOfExternalAllocatedMemory);
     WTF::initializeMainThread(callOnMainThreadFunction);
     Heap::init();
 
     ThreadState::attachMainThread();
     // currentThread() is null if we are running on a thread without a message loop.
     if (WebThread* currentThread = platform->currentThread()) {
         ASSERT(!s_gcTaskRunner);
         s_gcTaskRunner = new GCTaskRunner(currentThread);
     }
 
-    DEFINE_STATIC_LOCAL(ModulesInitializer, initializer, ());
-    initializer.init();
+    modulesInitializer().init();
 
     setIndexedDBClientCreateFunction(IndexedDBClientImpl::create);
 }
 
 void shutdown()
 {
 #if defined(LEAK_SANITIZER)
     // If LSan is about to perform leak detection, release all the registered
     // static Persistent<> root references to global caches that Blink keeps,
     // followed by GCs to clear out all they referred to. A full v8 GC cycle
@@ skipping 11 matching lines @@
     // currentThread() is null if we are running on a thread without a message loop.
     if (Platform::current()->currentThread()) {
         Platform::current()->unregisterMemoryDumpProvider(WebCacheMemoryDumpProvider::instance());
         Platform::current()->unregisterMemoryDumpProvider(FontCacheMemoryDumpProvider::instance());
 
         // We don't need to (cannot) remove s_endOfTaskRunner from the current
         // message loop, because the message loop is already destructed before
         // 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();
+
     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);

[haraken, 2016/03/03 12:08:46]

Line 210 - 213 should be moved to V8Initializer::shutdownMainThread. I'll do
that in a follow up.

 
     shutdownWithoutV8();
 }
 
 void shutdownWithoutV8()

[yhirano, 2016/03/03 18:03:11]

I would like to guarantee that all non-main thread is dead before this function
is called. Is it possible to decouple terminateThreads() from
ModuleInitializer::shutdown() and call the former in blink::shutdown()?

[haraken, 2016/03/03 23:47:37]

No, that is the key part of this CL. For example, modulesInitializer().init() in
initializeWithoutV8 creates a parser thread. So shutdownWithoutV8 must join the
parser thread. If we move it to shutdown, we end up with leaking the parser
thread in chromium tests that use a pair of
initializeWithoutV8/shutdownWithoutV8.

[yhirano, 2016/03/03 23:58:17]

modulesInitializer().init() creates a HTMLParserThread instance, but it will not
create a platform thread until HTMLParserThread::postTask is called. Is the
function called when initialize() is not called?

 {
+    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();
     WebPrerenderingSupport::shutdown();
     WTF::Partitions::shutdown();
 }
 
 // TODO(tkent): The following functions to wrap LayoutTestSupport should be
 // moved to public/platform/.
 
@@ skipping 46 matching lines @@
     ASSERT(!reloadPages);
     Page::refreshPlugins();
 }
 
 void decommitFreeableMemory()
 {
     WTF::Partitions::decommitFreeableMemory();
 }
 
 } // namespace blink