AuroraMiddleware/v8
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Rehash and clear deleted entries in weak collections during GC

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Otherwise, they'll just keep growing until we run out of memory or hit the FixedArray's maximum capacity.

BUG=v8:4909
R=hpayer@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/1877233005

Cr-Commit-Position: refs/heads/master@{#35514}
This commit is contained in:
jochen 2016-04-15 03:21:07 -07:00 committed by Commit bot
parent 71453f1c0f
commit e093a04779
5 changed files with 24 additions and 3 deletions
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7
src/heap/mark-compact.cc
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@ -2572,6 +2572,13 @@ void MarkCompactCollector::ClearWeakCollections() {
table->RemoveEntry(i);
}
}
// Rehash if more than 25% of the entries are deleted entries.
// TODO(jochen): Consider to shrink the fixed array in place.
if ((table->NumberOfDeletedElements() << kJSWeakCollectionLoadFactorExp) >
table->NumberOfElements()) {
HandleScope scope(heap()->isolate());
table->Rehash(heap()->isolate()->factory()->undefined_value());
}
}
weak_collection_obj = weak_collection->next();
weak_collection->set_next(heap()->undefined_value());

4
src/heap/mark-compact.h
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@ -512,6 +512,10 @@ class MarkCompactCollector {
static const uint32_t kSingleFreeEncoding = 0;
static const uint32_t kMultiFreeEncoding = 1;
// If the number of deleted slots in a JSWeakCollection exceeds the number
// of entries / 2^(factor), we rehash the table.
static const int kJSWeakCollectionLoadFactorExp = 1;
static inline bool IsMarked(Object* obj);
static bool IsUnmarkedHeapObjectWithHeap(Heap* heap, Object** p);

10
src/objects.cc
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@ -16860,6 +16860,16 @@ void HashTable<Derived, Shape, Key>::Rehash(Key key) {
}
}
}
// Wipe deleted entries.
Heap* heap = GetHeap();
Object* the_hole = heap->the_hole_value();
Object* undefined = heap->undefined_value();
for (uint32_t current = 0; current < capacity; current++) {
if (get(EntryToIndex(current)) == the_hole) {
set(EntryToIndex(current), undefined);
}
}
SetNumberOfDeletedElements(0);
}

2
test/cctest/test-weakmaps.cc
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@ -124,7 +124,7 @@ TEST(Weakness) {
heap->CollectAllGarbage(false);
CHECK_EQ(1, NumberOfWeakCalls);
CHECK_EQ(0, ObjectHashTable::cast(weakmap->table())->NumberOfElements());
CHECK_EQ(2,
CHECK_EQ(0,
ObjectHashTable::cast(weakmap->table())->NumberOfDeletedElements());
}

4
test/cctest/test-weaksets.cc
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@ -123,8 +123,8 @@ TEST(WeakSet_Weakness) {
heap->CollectAllGarbage(false);
CHECK_EQ(1, NumberOfWeakCalls);
CHECK_EQ(0, ObjectHashTable::cast(weakset->table())->NumberOfElements());
CHECK_EQ(
1, ObjectHashTable::cast(weakset->table())->NumberOfDeletedElements());
CHECK_EQ(0,
ObjectHashTable::cast(weakset->table())->NumberOfDeletedElements());
}