Fix the thresholds so that the heap does not grow uncontrollably. This fixes

src/heap.h

 // Copyright 2011 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 1191 matching lines @@
   inline bool OldGenerationPromotionLimitReached() {
     return (PromotedSpaceSize() + PromotedExternalMemorySize())
            > old_gen_promotion_limit_;
   }
 
   inline intptr_t OldGenerationSpaceAvailable() {
     return old_gen_allocation_limit_ -
            (PromotedSpaceSize() + PromotedExternalMemorySize());
   }
 
-  inline void LowerOldGenLimits(intptr_t bytes) {
-    old_gen_promotion_limit_ -= bytes;
-    old_gen_allocation_limit_ -= bytes;
+  static const intptr_t kMinimumPromotionLimit =
+      2 * (Page::kPageSize > MB ? Page::kPageSize : MB);
+  static const intptr_t kMinimumAllocationLimit =
+      8 * (Page::kPageSize > MB ? Page::kPageSize : MB);
+
+  // When we sweep lazily we initially guess that there is no garbage on the
+  // heap and set the limits for the next GC accordingly.  As we sweep we find
+  // out that some of the pages contained garbage and we have to adjust
+  // downwards the size of the heap.  This means the limits that control the
+  // timing of the next GC also need to be adjusted downwards.
+  void LowerOldGenLimits(intptr_t adjustment) {
+    size_of_old_gen_at_last_old_space_gc_ -= adjustment;
+    old_gen_promotion_limit_ =
+        OldGenPromotionLimit(size_of_old_gen_at_last_old_space_gc_);
+    old_gen_allocation_limit_ =
+        OldGenAllocationLimit(size_of_old_gen_at_last_old_space_gc_);
+  }
+
+  intptr_t OldGenPromotionLimit(intptr_t old_gen_size) {
+    intptr_t limit =
+        Max(old_gen_size + old_gen_size / 3, kMinimumPromotionLimit);
+    limit += new_space_.Capacity();

[Vyacheslav Egorov (Chromium), 2011/08/12 09:11:51]

new_space_.Capacity can change while lazy sweeping is in progress. 

So Lower... will fluctuate. Is it intentional?

[Erik Corry, 2011/08/12 09:21:48]

No, but I don't think it matters.

+    limit *= old_gen_limit_factor_;
+    return limit;
+  }
+
+  intptr_t OldGenAllocationLimit(intptr_t old_gen_size) {
+    intptr_t limit =
+        Max(old_gen_size + old_gen_size / 2, kMinimumAllocationLimit);
+    limit += new_space_.Capacity();
+    limit *= old_gen_limit_factor_;
+    return limit;
   }
 
   // Can be called when the embedding application is idle.
   bool IdleNotification();
 
   // Declare all the root indices.
   enum RootListIndex {
 #define ROOT_INDEX_DECLARATION(type, name, camel_name) k##camel_name##RootIndex,
     STRONG_ROOT_LIST(ROOT_INDEX_DECLARATION)
 #undef ROOT_INDEX_DECLARATION
@@ skipping 226 matching lines @@
   // Limit that triggers a global GC on the next (normally caused) GC.  This
   // is checked when we have already decided to do a GC to help determine
   // which collector to invoke.
   intptr_t old_gen_promotion_limit_;
 
   // Limit that triggers a global GC as soon as is reasonable.  This is
   // checked before expanding a paged space in the old generation and on
   // every allocation in large object space.
   intptr_t old_gen_allocation_limit_;
 
+  // Sometimes the heuristics dictate that those limits are increased.  This
+  // variable records that fact.
+  int old_gen_limit_factor_;
+
+  // Used to adjust the limits that control the timing of the next GC.
+  intptr_t size_of_old_gen_at_last_old_space_gc_;
+
   // Limit on the amount of externally allocated memory allowed
   // between global GCs. If reached a global GC is forced.
   intptr_t external_allocation_limit_;
 
   // The amount of external memory registered through the API kept alive
   // by global handles
   int amount_of_external_allocated_memory_;
 
   // Caches the amount of external memory registered at the last global gc.
   int amount_of_external_allocated_memory_at_last_global_gc_;
@@ skipping 916 matching lines @@
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG || LIVE_OBJECT_LIST
 
 } }  // namespace v8::internal
 
 #undef HEAP
 
 #endif  // V8_HEAP_H_