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..04d32eabddb249f8835a9c271f9a5950c5a80f48 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();
+
     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();
@@ -222,8 +217,20 @@ void shutdown()
 
 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();