Experimental change to idle notifications: Try to limit the...

src/heap.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3058 matching lines @@
 }
 
 
 bool Heap::IdleNotification() {
   static const int kIdlesBeforeScavenge = 4;
   static const int kIdlesBeforeMarkSweep = 7;
   static const int kIdlesBeforeMarkCompact = 8;
   static int number_idle_notifications = 0;
   static int last_gc_count = gc_count_;
 
-  if (!FLAG_expose_gc && (contexts_disposed_ > 0)) {
-    HistogramTimerScope scope(&Counters::gc_context);
-    CollectAllGarbage(false);
-    ASSERT(contexts_disposed_ == 0);
-    last_gc_count = gc_count_;
-    return false;
-  }
-
+  bool uncommit = true;
   bool finished = false;
 
   if (last_gc_count == gc_count_) {
     number_idle_notifications++;
   } else {
     number_idle_notifications = 0;
     last_gc_count = gc_count_;
   }
 
   if (number_idle_notifications == kIdlesBeforeScavenge) {
-    CollectGarbage(0, NEW_SPACE);
+    if (contexts_disposed_ > 0) {
+      HistogramTimerScope scope(&Counters::gc_context);
+      CollectAllGarbage(false);
+    } else {
+      CollectGarbage(0, NEW_SPACE);
+    }
     new_space_.Shrink();
     last_gc_count = gc_count_;
 
   } else if (number_idle_notifications == kIdlesBeforeMarkSweep) {
     // Before doing the mark-sweep collections we clear the
     // compilation cache to avoid hanging on to source code and
     // generated code for cached functions.
     CompilationCache::Clear();
 
     CollectAllGarbage(false);
     new_space_.Shrink();
     last_gc_count = gc_count_;
 
   } else if (number_idle_notifications == kIdlesBeforeMarkCompact) {
     CollectAllGarbage(true);
     new_space_.Shrink();
     last_gc_count = gc_count_;
     number_idle_notifications = 0;
     finished = true;
+
+  } else if (contexts_disposed_ > 0) {
+    if (FLAG_expose_gc) {
+      contexts_disposed_ = 0;
+    } else {
+      HistogramTimerScope scope(&Counters::gc_context);
+      CollectAllGarbage(false);
+      last_gc_count = gc_count_;
+    }
+    // If this is the first idle notification, we reset the
+    // notification count to avoid letting idle notifications for
+    // context disposal garbage collections start a potentially too
+    // aggressive idle GC cycle.
+    if (number_idle_notifications <= 1) {
+      number_idle_notifications = 0;
+      uncommit = false;
+    }
   }
 
-  // Uncommit unused memory in new space.
-  Heap::UncommitFromSpace();
+  // Make sure that we have no pending context disposals and
+  // conditionally uncommit from space.
+  ASSERT(contexts_disposed_ == 0);
+  if (uncommit) Heap::UncommitFromSpace();
   return finished;
 }
 
 
 #ifdef DEBUG
 
 void Heap::Print() {
   if (!HasBeenSetup()) return;
   Top::PrintStack();
   AllSpaces spaces;
@@ skipping 1103 matching lines @@
 void ExternalStringTable::TearDown() {
   new_space_strings_.Free();
   old_space_strings_.Free();
 }
 
 
 List<Object*> ExternalStringTable::new_space_strings_;
 List<Object*> ExternalStringTable::old_space_strings_;
 
 } }  // namespace v8::internal