Release evacuation candidates after parallel sweeper threads completed.

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index 5f22565fb9268a21bb5e548c9a74c8ed77067d82..bdbeaeaa152515e7d54b7464f1ee722baad3e2a0 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -535,7 +535,7 @@ void MarkCompactCollector::StartSweeperThreads() {
 }
 
 
-void MarkCompactCollector::WaitUntilSweepingCompleted() {
+bool MarkCompactCollector::WaitUntilSweepingCompleted() {

[Michael Starzinger, 2013/02/21 12:22:09]

Why do you return a boolean here? IMHO this makes the call sites too complex, I
would just rely on FinalizeSweeping() to be a no-op in those cases. I'll leave
that up to you.

[Hannes Payer (out of office), 2013/02/21 12:52:31]

Done.

   if (sweeping_pending_) {
     for (int i = 0; i < FLAG_sweeper_threads; i++) {
       heap()->isolate()->sweeper_threads()[i]->WaitForSweeperThread();
@@ -543,8 +543,9 @@ void MarkCompactCollector::WaitUntilSweepingCompleted() {
     sweeping_pending_ = false;
     StealMemoryFromSweeperThreads(heap()->paged_space(OLD_DATA_SPACE));
     StealMemoryFromSweeperThreads(heap()->paged_space(OLD_POINTER_SPACE));
-    heap()->FreeQueuedChunks();
+    return true;
   }
+  return false;
 }
 
 
@@ -568,6 +569,13 @@ bool MarkCompactCollector::IsConcurrentSweepingInProgress() {
 }
 
 
+void MarkCompactCollector::FinalizeSweeping() {
+  ASSERT(sweeping_pending_ == false);
+  ReleaseEvacuationCandidates();
+  heap()->FreeQueuedChunks();
+}
+
+
 void MarkCompactCollector::MarkInParallel() {
   for (int i = 0; i < FLAG_marking_threads; i++) {
     heap()->isolate()->marking_threads()[i]->StartMarking();
@@ -886,7 +894,9 @@ void MarkCompactCollector::Prepare(GCTracer* tracer) {
 
   if (AreSweeperThreadsActivated() && FLAG_concurrent_sweeping) {
     // Instead of waiting we could also abort the sweeper threads here.
-    WaitUntilSweepingCompleted();
+    if (WaitUntilSweepingCompleted()) {
+      FinalizeSweeping();
+    }
   }
 
   // Clear marking bits if incremental marking is aborted.
@@ -3280,6 +3290,11 @@ void MarkCompactCollector::EvacuateNewSpaceAndCandidates() {
 
   slots_buffer_allocator_.DeallocateChain(&migration_slots_buffer_);
   ASSERT(migration_slots_buffer_ == NULL);
+}
+
+
+void MarkCompactCollector::ReleaseEvacuationCandidates() {
+  int npages = evacuation_candidates_.length();
   for (int i = 0; i < npages; i++) {
     Page* p = evacuation_candidates_[i];
     if (!p->IsEvacuationCandidate()) continue;
@@ -3877,6 +3892,10 @@ void MarkCompactCollector::SweepSpaces() {
 
   // Deallocate unmarked objects and clear marked bits for marked objects.
   heap_->lo_space()->FreeUnmarkedObjects();
+
+  if (!FLAG_concurrent_sweeping) {

[Michael Starzinger, 2013/02/21 12:22:09]

This is still not entirely correct, it _has_ to depend of the how_to_sweep
variable because that determines how the pages were swept.

[Hannes Payer (out of office), 2013/02/21 12:52:31]

Done.

+    FinalizeSweeping();
+  }
 }