Tweak compaction candidate selection to avoid keeping page with low occupancy around.

src/profile-generator.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 1544 matching lines @@
 void HeapSnapshotsCollection::RemoveSnapshot(HeapSnapshot* snapshot) {
   snapshots_.RemoveElement(snapshot);
   unsigned uid = snapshot->uid();
   snapshots_uids_.Remove(reinterpret_cast<void*>(uid),
                          static_cast<uint32_t>(uid));
 }
 
 
 Handle<HeapObject> HeapSnapshotsCollection::FindHeapObjectById(uint64_t id) {
   // First perform a full GC in order to avoid dead objects.
-  HEAP->CollectAllGarbage(Heap::kMakeHeapIterableMask);
+  HEAP->CollectAllGarbage(Heap::kMakeHeapIterableMask,
+                          "HeapSnapshotsCollection::FindHeapObjectById");
   AssertNoAllocation no_allocation;
   HeapObject* object = NULL;
   HeapIterator iterator(HeapIterator::kFilterUnreachable);
   // Make sure that object with the given id is still reachable.
   for (HeapObject* obj = iterator.next();
        obj != NULL;
        obj = iterator.next()) {
     if (ids_.FindObject(obj->address()) == id) {
       ASSERT(object == NULL);
       object = obj;
@@ skipping 1465 matching lines @@
 };
 
 
 bool HeapSnapshotGenerator::GenerateSnapshot() {
   v8_heap_explorer_.TagGlobalObjects();
 
   // TODO(1562) Profiler assumes that any object that is in the heap after
   // full GC is reachable from the root when computing dominators.
   // This is not true for weakly reachable objects.
   // As a temporary solution we call GC twice.
-  Isolate::Current()->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask);
-  Isolate::Current()->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask);
+  Isolate::Current()->heap()->CollectAllGarbage(
+      Heap::kMakeHeapIterableMask,
+      "HeapSnapshotGenerator::GenerateSnapshot");
+  Isolate::Current()->heap()->CollectAllGarbage(
+      Heap::kMakeHeapIterableMask,
+      "HeapSnapshotGenerator::GenerateSnapshot");
 
 #ifdef DEBUG
   Heap* debug_heap = Isolate::Current()->heap();
   ASSERT(!debug_heap->old_data_space()->was_swept_conservatively());
   ASSERT(!debug_heap->old_pointer_space()->was_swept_conservatively());
   ASSERT(!debug_heap->code_space()->was_swept_conservatively());
   ASSERT(!debug_heap->cell_space()->was_swept_conservatively());
   ASSERT(!debug_heap->map_space()->was_swept_conservatively());
 #endif
 
@@ skipping 596 matching lines @@
 
 
 void HeapSnapshotJSONSerializer::SortHashMap(
     HashMap* map, List<HashMap::Entry*>* sorted_entries) {
   for (HashMap::Entry* p = map->Start(); p != NULL; p = map->Next(p))
     sorted_entries->Add(p);
   sorted_entries->Sort(SortUsingEntryValue);
 }
 
 } }  // namespace v8::internal