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

src/global-handles.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/api.h"
 #include "src/global-handles.h"
 
 #include "src/vm-state-inl.h"
@@ skipping 477 matching lines @@
     block_ = block_->next_used();
   }
 
  private:
   NodeBlock* block_;
   int index_;
 
   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),
       number_of_global_handles_(0),
       first_block_(NULL),
       first_used_block_(NULL),
       first_free_(NULL),
       post_gc_processing_count_(0),
       object_group_connections_(kObjectGroupConnectionsCapacity) {}
 
@@ skipping 289 matching lines @@
     // The initial pass callbacks must simply clear the nodes.
     for (auto i = pending_phantom_callbacks_.begin();
          i != pending_phantom_callbacks_.end(); ++i) {
       auto callback = i;
       // Skip callbacks that have already been processed once.
       if (callback->node() == nullptr) continue;
       callback->Invoke(isolate());
       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;
 }
 
 
 void GlobalHandles::PendingPhantomCallback::Invoke(Isolate* isolate) {
   Data::Callback* callback_addr = nullptr;
   if (node_ != nullptr) {
     // Initialize for first pass callback.
@@ skipping 401 matching lines @@
   blocks_[block][offset] = object;
   if (isolate->heap()->InNewSpace(object)) {
     new_space_indices_.Add(size_);
   }
   *index = size_++;
 }
 
 
 }  // namespace internal
 }  // namespace v8