Check if there is still time before finalizing an incremental collection.

src/heap/incremental-marking.cc

Index: src/heap/incremental-marking.cc
diff --git a/src/heap/incremental-marking.cc b/src/heap/incremental-marking.cc
index d72423a60aa81619516404c2995ebc26df4e60a2..c3f60f4bc66950f6ffbdc533b2a6b56bd5a953c6 100644
--- a/src/heap/incremental-marking.cc
+++ b/src/heap/incremental-marking.cc
@@ -27,6 +27,7 @@ IncrementalMarking::IncrementalMarking(Heap* heap)
       should_hurry_(false),
       marking_speed_(0),
       allocated_(0),
+      idle_marking_delay_counter_(0),
       no_marking_scope_depth_(0),
       unscanned_bytes_of_large_object_(0) {}
 
@@ -893,7 +894,7 @@ void IncrementalMarking::SpeedUp() {
 
 
 void IncrementalMarking::Step(intptr_t allocated_bytes, CompletionAction action,
-                              bool force_marking) {
+                              bool force_marking, bool force_completion) {
   if (heap_->gc_state() != Heap::NOT_IN_GC || !FLAG_incremental_marking ||
       !FLAG_incremental_marking_steps ||
       (state_ != SWEEPING && state_ != MARKING)) {
@@ -943,7 +944,11 @@ void IncrementalMarking::Step(intptr_t allocated_bytes, CompletionAction action,
       }
     } else if (state_ == MARKING) {
       bytes_processed = ProcessMarkingDeque(bytes_to_process);
-      if (marking_deque_.IsEmpty()) MarkingComplete(action);
+      IncrementIdleMarkingDelayCounter();

[Erik Corry Chromium.org, 2014/10/06 14:56:47]

If we increment this every time we do a step, then I think it will always be
above 3 when we check it.  What am I missing?

[Hannes Payer (out of office), 2014/10/07 13:41:11]

Uff, good catch. We should just increment the counter when we finish marking but
do not complete. Done.

+      if (marking_deque_.IsEmpty() &&
+          (force_completion || IsIdleMarkingDelayCounterLimitReached())) {
+        MarkingComplete(action);
+      }
     }
 
     steps_count_++;
@@ -978,5 +983,20 @@ void IncrementalMarking::ResetStepCounters() {
 int64_t IncrementalMarking::SpaceLeftInOldSpace() {
   return heap_->MaxOldGenerationSize() - heap_->PromotedSpaceSizeOfObjects();
 }
+
+
+bool IncrementalMarking::IsIdleMarkingDelayCounterLimitReached() {
+  return idle_marking_delay_counter_ >= kMaxIdleMarkingDelayCounter;
+}
+
+
+void IncrementalMarking::IncrementIdleMarkingDelayCounter() {
+  idle_marking_delay_counter_++;
+}
+
+
+void IncrementalMarking::ClearIdleMarkingDelayCounter() {
+  idle_marking_delay_counter_ = 0;
+}
 }
 }  // namespace v8::internal