Shrink the new space and uncommit marking deque on low memory notification.

src/heap.cc

 // 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 429 matching lines @@
   // cause a full GC.
   // Major GC would invoke weak handle callbacks on weakly reachable
   // handles, but won't collect weakly reachable objects until next
   // major GC.  Therefore if we collect aggressively and weak handle callback
   // has been invoked, we rerun major GC to release objects which become
   // garbage.
   // Note: as weak callbacks can execute arbitrary code, we cannot
   // hope that eventually there will be no weak callbacks invocations.
   // Therefore stop recollecting after several attempts.
   mark_compact_collector()->SetFlags(kMakeHeapIterableMask);
+  isolate_->compilation_cache()->Clear();
   const int kMaxNumberOfAttempts = 7;
   for (int attempt = 0; attempt < kMaxNumberOfAttempts; attempt++) {
     if (!CollectGarbage(OLD_POINTER_SPACE, MARK_COMPACTOR)) {
       break;
     }
   }
   mark_compact_collector()->SetFlags(kNoGCFlags);
+  new_space_.Shrink();
+  incremental_marking()->UncommitMarkingDeque();
 }
 
 
 bool Heap::CollectGarbage(AllocationSpace space, GarbageCollector collector) {
   // The VM is in the GC state until exiting this function.
   VMState state(isolate_, GC);
 
 #ifdef DEBUG
   // Reset the allocation timeout to the GC interval, but make sure to
   // allow at least a few allocations after a collection. The reason
@@ skipping 5943 matching lines @@
   isolate_->heap()->store_buffer()->Compact();
   isolate_->heap()->store_buffer()->Filter(MemoryChunk::ABOUT_TO_BE_FREED);
   for (chunk = chunks_queued_for_free_; chunk != NULL; chunk = next) {
     next = chunk->next_chunk();
     isolate_->memory_allocator()->Free(chunk);
   }
   chunks_queued_for_free_ = NULL;
 }
 
 } }  // namespace v8::internal