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[heap] Adjust condition for AdjustLiveBytes to avoid concurrent access w/ sweeper

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A concurrent sweeper thread can access the same markbit cell as the main thread
during right trimming a fixed array, resulting in a data race on a markbit cell.
Previously we checked whether we were currently marking incrementally, filtering
out this case.

The current check has the benefit of keeping live_bytes accurate (modulo other
bugs) until the sweeper starts.

BUG=chromium:576193
LOG=N

Review URL: https://codereview.chromium.org/1576853002

Cr-Commit-Position: refs/heads/master@{#33203}
This commit is contained in:
mlippautz 2016-01-11 04:58:03 -08:00 committed by Commit bot
parent 3ae141c121
commit 779aa924f6
2 changed files with 2 additions and 1 deletions
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1
src/heap/heap.cc
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@ -3109,6 +3109,7 @@ void Heap::AdjustLiveBytes(HeapObject* object, int by, InvocationMode mode) {
// update while using HeapIterator because the iterator is temporarily // update while using HeapIterator because the iterator is temporarily
// marking the whole object graph, without updating live bytes. // marking the whole object graph, without updating live bytes.
if (!in_heap_iterator() && if (!in_heap_iterator() &&
!mark_compact_collector()->sweeping_in_progress() &&
Marking::IsBlack(Marking::MarkBitFrom(object->address()))) { Marking::IsBlack(Marking::MarkBitFrom(object->address()))) {
if (mode == SEQUENTIAL_TO_SWEEPER) { if (mode == SEQUENTIAL_TO_SWEEPER) {
MemoryChunk::IncrementLiveBytesFromGC(object, by); MemoryChunk::IncrementLiveBytesFromGC(object, by);

2
src/heap/mark-compact.cc
View File

@ -3982,6 +3982,7 @@ void MarkCompactCollector::SweepSpaces() {
MoveEvacuationCandidatesToEndOfPagesList(); MoveEvacuationCandidatesToEndOfPagesList();
{ {
sweeping_in_progress_ = true;
{ {
GCTracer::Scope sweep_scope(heap()->tracer(), GCTracer::Scope sweep_scope(heap()->tracer(),
GCTracer::Scope::MC_SWEEP_OLD); GCTracer::Scope::MC_SWEEP_OLD);
@ -3997,7 +3998,6 @@ void MarkCompactCollector::SweepSpaces() {
GCTracer::Scope::MC_SWEEP_MAP); GCTracer::Scope::MC_SWEEP_MAP);
StartSweepSpace(heap()->map_space()); StartSweepSpace(heap()->map_space());
} }
sweeping_in_progress_ = true;
if (FLAG_concurrent_sweeping) { if (FLAG_concurrent_sweeping) {
StartSweeperThreads(); StartSweeperThreads();
} }