Perform context disposal garbage collections only if contexts disposals happen at a high rate.

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 847 matching lines @@
 }
 
 
 int Heap::NotifyContextDisposed() {
   if (isolate()->concurrent_recompilation_enabled()) {
     // Flush the queued recompilation tasks.
     isolate()->optimizing_compiler_thread()->Flush();
   }
   flush_monomorphic_ics_ = true;
   AgeInlineCaches();
+  tracer()->AddContextDisposalTime(base::OS::TimeCurrentMillis());
   return ++contexts_disposed_;
 }
 
 
 void Heap::MoveElements(FixedArray* array, int dst_index, int src_index,
                         int len) {
   if (len == 0) return;
 
   DCHECK(array->map() != fixed_cow_array_map());
   Object** dst_objects = array->data_start() + dst_index;
@@ skipping 3478 matching lines @@
   if (!FLAG_incremental_marking) return true;
   base::ElapsedTimer timer;
   timer.Start();
   isolate()->counters()->gc_idle_time_allotted_in_ms()->AddSample(
       idle_time_in_ms);
   HistogramTimerScope idle_notification_scope(
       isolate_->counters()->gc_idle_notification());
 
   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();
   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>(
@@ skipping 1886 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