Limit rate of full garbage collections triggered by idle notification.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 483b091035fb61fc1023c3ceae383a97d071b5bc..7ca5eebcb719e11ac8b0c7324ff5847c3d4a04de 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -4597,6 +4597,7 @@ bool Heap::IdleNotification(double deadline_in_seconds) {
       static_cast<double>(base::Time::kMillisecondsPerSecond);
   HistogramTimerScope idle_notification_scope(
       isolate_->counters()->gc_idle_notification());
+  double current_time = MonotonicallyIncreasingTimeInMs();
 
   GCIdleTimeHandler::HeapState heap_state;
   heap_state.contexts_disposed = contexts_disposed_;
@@ -4623,8 +4624,11 @@ bool Heap::IdleNotification(double deadline_in_seconds) {
   heap_state.new_space_allocation_throughput_in_bytes_per_ms =
       static_cast<size_t>(
           tracer()->NewSpaceAllocationThroughputInBytesPerMillisecond());
+  heap_state.last_mark_compact_time =
+      mark_compact_collector()->last_mark_compact_time();
+  heap_state.current_time = static_cast<size_t>(current_time);

[rmcilroy, 2015/03/20 14:56:08]

I'm slightly hesitent at setting current_time as a field in heap_state, because
it might lead it to be used at a much later point in time (when it doesn't
represent the actual current time). I realize making this a separate variable
won't change too much but might make this more obvious, WDYT?

 
-  double idle_time_in_ms = deadline_in_ms - MonotonicallyIncreasingTimeInMs();
+  double idle_time_in_ms = deadline_in_ms - current_time;
   GCIdleTimeAction action =
       gc_idle_time_handler_.Compute(idle_time_in_ms, heap_state);
   isolate()->counters()->gc_idle_time_allotted_in_ms()->AddSample(
@@ -4679,7 +4683,7 @@ bool Heap::IdleNotification(double deadline_in_seconds) {
       break;
   }
 
-  double current_time = MonotonicallyIncreasingTimeInMs();
+  current_time = MonotonicallyIncreasingTimeInMs();
   last_idle_notification_time_ = current_time;
   double deadline_difference = deadline_in_ms - current_time;