Let the second pass phantom callbacks run in a separate task on the foreground thread.

src/global-handles.cc

Index: src/global-handles.cc
diff --git a/src/global-handles.cc b/src/global-handles.cc
index aa6542baee922f8f4e517cd6764f8b8ed71290ee..004e55b5bfcd8162fa4bb44d18d8111b35daa13a 100644
--- a/src/global-handles.cc
+++ b/src/global-handles.cc
@@ -495,6 +495,35 @@ class GlobalHandles::NodeIterator {
   DISALLOW_COPY_AND_ASSIGN(NodeIterator);
 };
 
+class GlobalHandles::PendingPhantomCallbacksSecondPassTask : public v8::Task {
+ public:
+  // Takes ownership of the contents of pending_phantom_callbacks, leaving it in
+  // the same state it would be after a call to Clear().
+  PendingPhantomCallbacksSecondPassTask(
+      List<PendingPhantomCallback>* pending_phantom_callbacks, Isolate* isolate)
+      : isolate_(isolate) {
+    pending_phantom_callbacks_.Swap(pending_phantom_callbacks);
+  }
+
+  ~PendingPhantomCallbacksSecondPassTask() override {}
+
+  void Run() override {
+    while (pending_phantom_callbacks_.length() != 0) {
+      auto callback = pending_phantom_callbacks_.RemoveLast();
+      DCHECK(callback.node() == nullptr);
+      // No second pass callback required.
+      if (callback.callback() == nullptr) continue;
+      // Fire second pass callback
+      callback.Invoke(isolate_);
+    }
+    pending_phantom_callbacks_.Clear();
+  }
+
+ private:
+  List<PendingPhantomCallback> pending_phantom_callbacks_;
+  Isolate* isolate_;
+};

[jochen (gone - plz use gerrit), 2015/07/03 12:42:27]

nit. DISALLOW_COPY_AND_ASSIGN(PendingPhantomCallbacksSecondPassTask)

[epertoso, 2015/07/03 14:38:00]

Done.

+
 
 GlobalHandles::GlobalHandles(Isolate* isolate)
     : isolate_(isolate),
@@ -804,14 +833,11 @@ int GlobalHandles::DispatchPendingPhantomCallbacks() {
       freed_nodes++;
     }
   }
-  // The second pass empties the list.
-  while (pending_phantom_callbacks_.length() != 0) {
-    auto callback = pending_phantom_callbacks_.RemoveLast();
-    DCHECK(callback.node() == nullptr);
-    // No second pass callback required.
-    if (callback.callback() == nullptr) continue;
-    // Fire second pass callback.
-    callback.Invoke(isolate());
+  if (pending_phantom_callbacks_.length() > 0) {
+    auto* task = new PendingPhantomCallbacksSecondPassTask(
+        &pending_phantom_callbacks_, isolate());
+    V8::GetCurrentPlatform()->CallOnForegroundThread(
+        reinterpret_cast<v8::Isolate*>(isolate()), task);
   }
   pending_phantom_callbacks_.Clear();
   return freed_nodes;