Make allocation tracker use less memory
The allocation tracker no longer keeps recently allocated objects live.
Instead it just keeps their class objects live as strong roots. This fixed
the gc-stress test failure for 098-ddmc.
Also fixed the issue in DisableNewSystemWeak() for allocation tracker,
by making new allocation to wait until GC's sweeping to complete. I didn't
feel any significant slowdown with this wait.
Bug: 20037135
Change-Id: I6a98188832cf7ee478007e3788e742dc6e18f7b8
diff --git a/runtime/gc/allocation_record.cc b/runtime/gc/allocation_record.cc
index ac7de63..c5b9f65 100644
--- a/runtime/gc/allocation_record.cc
+++ b/runtime/gc/allocation_record.cc
@@ -94,33 +94,58 @@
CHECK_LE(recent_record_max_, alloc_record_max_);
BufferedRootVisitor<kDefaultBufferedRootCount> buffered_visitor(visitor, RootInfo(kRootDebugger));
size_t count = recent_record_max_;
- // Only visit the last recent_record_max_ number of objects in entries_.
- // They need to be retained for DDMS's recent allocation tracking.
- // TODO: This will cause 098-ddmc test to run out of memory for GC stress test.
- // There should be an option that do not keep these objects live if allocation tracking is only
- // for the purpose of an HPROF dump. b/20037135
+ // Only visit the last recent_record_max_ number of allocation records in entries_ and mark the
+ // klass_ fields as strong roots.
for (auto it = entries_.rbegin(), end = entries_.rend(); count > 0 && it != end; count--, ++it) {
- buffered_visitor.VisitRoot(it->first);
+ buffered_visitor.VisitRoot(it->second->GetClassGcRoot());
+ }
+}
+
+static inline void SweepClassObject(AllocRecord* record, IsMarkedCallback* callback, void* arg)
+ SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
+ EXCLUSIVE_LOCKS_REQUIRED(Locks::alloc_tracker_lock_) {
+ GcRoot<mirror::Class>& klass = record->GetClassGcRoot();
+ // This does not need a read barrier because this is called by GC.
+ mirror::Object* old_object = klass.Read<kWithoutReadBarrier>();
+ mirror::Object* new_object = callback(old_object, arg);
+ if (UNLIKELY(old_object != new_object)) {
+ mirror::Class* new_klass = (UNLIKELY(new_object == nullptr) ? nullptr : new_object->AsClass());
+ klass = GcRoot<mirror::Class>(new_klass);
}
}
void AllocRecordObjectMap::SweepAllocationRecords(IsMarkedCallback* callback, void* arg) {
VLOG(heap) << "Start SweepAllocationRecords()";
- size_t count_deleted = 0, count_moved = 0;
+ size_t count_deleted = 0, count_moved = 0, count = 0;
+ // Only the first (size - recent_record_max_) number of records can be deleted.
+ size_t delete_bound;
+ if (entries_.size() <= recent_record_max_) {
+ delete_bound = 0;
+ } else {
+ delete_bound = entries_.size() - recent_record_max_;
+ }
for (auto it = entries_.begin(), end = entries_.end(); it != end;) {
+ ++count;
// This does not need a read barrier because this is called by GC.
mirror::Object* old_object = it->first.Read<kWithoutReadBarrier>();
AllocRecord* record = it->second;
mirror::Object* new_object = callback(old_object, arg);
if (new_object == nullptr) {
- delete record;
- it = entries_.erase(it);
- ++count_deleted;
+ if (count > delete_bound) {
+ it->first = GcRoot<mirror::Object>(nullptr);
+ SweepClassObject(record, callback, arg);
+ ++it;
+ } else {
+ delete record;
+ it = entries_.erase(it);
+ ++count_deleted;
+ }
} else {
if (old_object != new_object) {
it->first = GcRoot<mirror::Object>(new_object);
++count_moved;
}
+ SweepClassObject(record, callback, arg);
++it;
}
}
@@ -128,6 +153,20 @@
VLOG(heap) << "Updated " << count_moved << " allocation records";
}
+void AllocRecordObjectMap::AllowNewAllocationRecords() {
+ allow_new_record_ = true;
+ new_record_condition_.Broadcast(Thread::Current());
+}
+
+void AllocRecordObjectMap::DisallowNewAllocationRecords() {
+ allow_new_record_ = false;
+}
+
+void AllocRecordObjectMap::EnsureNewAllocationRecordsDisallowed() {
+ CHECK(!allow_new_record_);
+}
+
+
struct AllocRecordStackVisitor : public StackVisitor {
AllocRecordStackVisitor(Thread* thread, AllocRecordStackTrace* trace_in, size_t max)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
@@ -201,7 +240,8 @@
}
}
-void AllocRecordObjectMap::RecordAllocation(Thread* self, mirror::Object* obj, size_t byte_count) {
+void AllocRecordObjectMap::RecordAllocation(Thread* self, mirror::Object* obj, mirror::Class* klass,
+ size_t byte_count) {
MutexLock mu(self, *Locks::alloc_tracker_lock_);
Heap* heap = Runtime::Current()->GetHeap();
if (!heap->IsAllocTrackingEnabled()) {
@@ -217,6 +257,11 @@
return;
}
+ // Wait for GC's sweeping to complete and allow new records
+ while (UNLIKELY(!records->allow_new_record_)) {
+ records->new_record_condition_.WaitHoldingLocks(self);
+ }
+
DCHECK_LE(records->Size(), records->alloc_record_max_);
// Get stack trace.
@@ -229,7 +274,7 @@
AllocRecordStackTrace* trace = new AllocRecordStackTrace(records->scratch_trace_);
// Fill in the basics.
- AllocRecord* record = new AllocRecord(byte_count, trace);
+ AllocRecord* record = new AllocRecord(byte_count, klass, trace);
records->Put(obj, record);
DCHECK_LE(records->Size(), records->alloc_record_max_);