Ensure that GC idle notifications either make progress or stop requesting more GCs.

src/heap/gc-idle-time-handler.h

 // Copyright 2014 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.
 
 #ifndef V8_HEAP_GC_IDLE_TIME_HANDLER_H_
 #define V8_HEAP_GC_IDLE_TIME_HANDLER_H_
 
 #include "src/globals.h"
 
 namespace v8 {
@@ skipping 120 matching lines @@
   static const size_t kInitialConservativeScavengeSpeed = 100 * KB;
 
   // If contexts are disposed at a higher rate a full gc is triggered.
   static const double kHighContextDisposalRate;
 
   // Incremental marking step time.
   static const size_t kIncrementalMarkingStepTimeInMs = 1;
 
   static const size_t kMinTimeForOverApproximatingWeakClosureInMs;
 
+  // Number of times we will return a Nothing action per Idle round despite
+  // having idle time available before we returning a Done action to ensure we
+  // don't keep scheduling idle tasks and making no progress.
+  static const int kMaxNoProgressIdleTimesPerIdleRound = 10;
+
   class HeapState {
    public:
     void Print();
 
     int contexts_disposed;
     double contexts_disposal_rate;
     size_t size_of_objects;
     bool incremental_marking_stopped;
     bool can_start_incremental_marking;
     bool sweeping_in_progress;
     bool sweeping_completed;
     size_t mark_compact_speed_in_bytes_per_ms;
     size_t incremental_marking_speed_in_bytes_per_ms;
     size_t final_incremental_mark_compact_speed_in_bytes_per_ms;
     size_t scavenge_speed_in_bytes_per_ms;
     size_t used_new_space_size;
     size_t new_space_capacity;
     size_t new_space_allocation_throughput_in_bytes_per_ms;
   };
 
   GCIdleTimeHandler()
       : mark_compacts_since_idle_round_started_(0),
-        scavenges_since_last_idle_round_(0) {}
+        scavenges_since_last_idle_round_(0),
+        idle_times_which_made_no_progress_since_last_idle_round_(0) {}
 
   GCIdleTimeAction Compute(double idle_time_in_ms, HeapState heap_state);
 
   void NotifyIdleMarkCompact() {
     if (mark_compacts_since_idle_round_started_ < kMaxMarkCompactsInIdleRound) {
       ++mark_compacts_since_idle_round_started_;
       if (mark_compacts_since_idle_round_started_ ==
           kMaxMarkCompactsInIdleRound) {
         scavenges_since_last_idle_round_ = 0;
       }
@@ skipping 23 matching lines @@
       size_t final_incremental_mark_compact_speed_in_bytes_per_ms);
 
   static bool ShouldDoOverApproximateWeakClosure(size_t idle_time_in_ms);
 
   static bool ShouldDoScavenge(
       size_t idle_time_in_ms, size_t new_space_size, size_t used_new_space_size,
       size_t scavenger_speed_in_bytes_per_ms,
       size_t new_space_allocation_throughput_in_bytes_per_ms);
 
  private:
-  void StartIdleRound() { mark_compacts_since_idle_round_started_ = 0; }
+  GCIdleTimeAction NothingOrDone();
+
+  void StartIdleRound() {
+    mark_compacts_since_idle_round_started_ = 0;
+    idle_times_which_made_no_progress_since_last_idle_round_ = 0;
+  }
   bool IsMarkCompactIdleRoundFinished() {
     return mark_compacts_since_idle_round_started_ ==
            kMaxMarkCompactsInIdleRound;
   }
   bool EnoughGarbageSinceLastIdleRound() {
     return scavenges_since_last_idle_round_ >= kIdleScavengeThreshold;
   }
 
   int mark_compacts_since_idle_round_started_;
   int scavenges_since_last_idle_round_;
+  int idle_times_which_made_no_progress_since_last_idle_round_;
 
   DISALLOW_COPY_AND_ASSIGN(GCIdleTimeHandler);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_GC_IDLE_TIME_HANDLER_H_