Limit rate of full garbage collections triggered by idle notification.

src/heap/heap.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/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 4579 matching lines @@
 }
 
 
 bool Heap::IdleNotification(double deadline_in_seconds) {
   CHECK(HasBeenSetUp());  // http://crbug.com/425035
   double deadline_in_ms =
       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_;
   heap_state.contexts_disposal_rate =
       tracer()->ContextDisposalRateInMilliseconds();
   heap_state.size_of_objects = static_cast<size_t>(SizeOfObjects());
   heap_state.incremental_marking_stopped = incremental_marking()->IsStopped();
   // TODO(ulan): Start incremental marking only for large heaps.
   heap_state.can_start_incremental_marking =
       incremental_marking()->ShouldActivate() && FLAG_incremental_marking;
   heap_state.sweeping_in_progress =
       mark_compact_collector()->sweeping_in_progress();
   heap_state.mark_compact_speed_in_bytes_per_ms =
       static_cast<size_t>(tracer()->MarkCompactSpeedInBytesPerMillisecond());
   heap_state.incremental_marking_speed_in_bytes_per_ms = static_cast<size_t>(
       tracer()->IncrementalMarkingSpeedInBytesPerMillisecond());
   heap_state.final_incremental_mark_compact_speed_in_bytes_per_ms =
       static_cast<size_t>(
           tracer()->FinalIncrementalMarkCompactSpeedInBytesPerMillisecond());
   heap_state.scavenge_speed_in_bytes_per_ms =
       static_cast<size_t>(tracer()->ScavengeSpeedInBytesPerMillisecond());
   heap_state.used_new_space_size = new_space_.Size();
   heap_state.new_space_capacity = new_space_.Capacity();
   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(
       static_cast<int>(idle_time_in_ms));
 
   bool result = false;
   switch (action.type) {
     case DONE:
       result = true;
       break;
@@ skipping 34 matching lines @@
     case DO_SCAVENGE:
       CollectGarbage(NEW_SPACE, "idle notification: scavenge");
       break;
     case DO_FINALIZE_SWEEPING:
       mark_compact_collector()->EnsureSweepingCompleted();
       break;
     case DO_NOTHING:
       break;
   }
 
-  double current_time = MonotonicallyIncreasingTimeInMs();
+  current_time = MonotonicallyIncreasingTimeInMs();
   last_idle_notification_time_ = current_time;
   double deadline_difference = deadline_in_ms - current_time;
 
   if (deadline_difference >= 0) {
     if (action.type != DONE && action.type != DO_NOTHING) {
       isolate()->counters()->gc_idle_time_limit_undershot()->AddSample(
           static_cast<int>(deadline_difference));
     }
   } else {
     isolate()->counters()->gc_idle_time_limit_overshot()->AddSample(
@@ skipping 1692 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 }
 }  // namespace v8::internal