Check whether the marking deque overflowed in ProcessEphemeralMarking

src/heap/mark-compact.cc

 // Copyright 2012 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/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
@@ skipping 2073 matching lines @@
     EmptyMarkingDeque();
   }
 }
 
 
 // Mark all objects reachable (transitively) from objects on the marking
 // stack including references only considered in the atomic marking pause.
 void MarkCompactCollector::ProcessEphemeralMarking(
     ObjectVisitor* visitor, bool only_process_harmony_weak_collections) {
   bool work_to_do = true;
   DCHECK(marking_deque_.IsEmpty());

[Erik Corry, 2014/12/03 13:09:12]

Thinking about it some more, we should just empty the deque here (including
overflows).  This method should not assume stuff about the situation coming in,
there's no reason for that.

And then there's no need to check for overflow in the loop, since you can't have
an empty deque and an overflow unless you somehow processed the deque, and if
you did that you broke things anyway because this function relies on being able
to see whether anything was pushed on the deque.

   while (work_to_do) {
     if (!only_process_harmony_weak_collections) {
       isolate()->global_handles()->IterateObjectGroups(
           visitor, &IsUnmarkedHeapObjectWithHeap);
       MarkImplicitRefGroups();
     }
     ProcessWeakCollections();
-    work_to_do = !marking_deque_.IsEmpty();
+    work_to_do = !marking_deque_.IsEmpty() || marking_deque_.overflowed();

[Erik Corry, 2014/12/03 12:46:21]

It would be better to improve MarkCompactCollector::IsMarkingStackEmpty() to
include both these conditions and then use it here and in the DCHECK above. 
There are also about 5 places in incremental-marking.cc that check for an empty
stack, and at least some of them should use this check instead.

I see Hannes just moved that function, so maybe it should be changed in its new
location (incremental-marking.somthing)

[Hannes Payer (out of office), 2014/12/03 13:18:24]

Let's do that.

     ProcessMarkingDeque();
   }
 }
 
 
 void MarkCompactCollector::ProcessTopOptimizedFrame(ObjectVisitor* visitor) {
   for (StackFrameIterator it(isolate(), isolate()->thread_local_top());
        !it.done(); it.Advance()) {
     if (it.frame()->type() == StackFrame::JAVA_SCRIPT) {
       return;
@@ skipping 2326 matching lines @@
   SlotsBuffer* buffer = *buffer_address;
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 }
 }  // namespace v8::internal