Oilpan: We need to collect all garbage before shutting down the worker thread

Source/heap/ThreadState.cpp

Index: Source/heap/ThreadState.cpp
diff --git a/Source/heap/ThreadState.cpp b/Source/heap/ThreadState.cpp
index 233a979afe7ea6e39a9d325529717307e42d90a9..763d22cf16f5af91a1a6713920456ddb2dc5710b 100644
--- a/Source/heap/ThreadState.cpp
+++ b/Source/heap/ThreadState.cpp
@@ -296,13 +296,7 @@ void ThreadState::cleanup()
     // After this GC we expect heap to be empty because
     // preCleanup tasks should have cleared all persistent
     // handles that were externally owned.
-    // FIXME: oilpan: we should perform a single GC and everything
-    // should die. Unfortunately it is not the case for all objects
-    // because the hierarchy was not completely moved to the heap and
-    // some heap allocated objects own objects that contain persistents
-    // pointing to other heap allocated objects.
-    Heap::collectGarbage(ThreadState::NoHeapPointersOnStack);
-    Heap::collectGarbage(ThreadState::NoHeapPointersOnStack);
+    Heap::collectAllGarbage(ThreadState::NoHeapPointersOnStack);
 
     // Verify that all heaps are empty now.
     for (int i = 0; i < NumberOfHeaps; i++)
@@ -317,6 +311,16 @@ void ThreadState::cleanup()
 void ThreadState::detach()
 {
     ThreadState* state = current();
+
+    // When ThreadState is detaching from non-main thread its

[Mads Ager (chromium), 2014/03/05 07:40:34]

Ah, you moved it here. Have the comment on what cleanup does in the header file
with the other comments?

[haraken, 2014/03/05 08:50:26]

Done.

+    // heap is expected to be empty (because it is going away).
+    // Perform registered cleanup tasks and garbage collection
+    // to sweep away any objects that are left on this heap.
+    // We assert that nothing must remain after this cleanup.
+    // If assertion does not hold we crash as we are potentially
+    // in the dangling pointer situation.
+    state->cleanup();
+
     // Enter safe point before trying to acquire threadAttachMutex
     // to avoid dead lock if another thread is preparing for GC, has acquired
     // threadAttachMutex and waiting for other threads to pause or reach a