| // Copyright 2017 the V8 project authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "src/heap/concurrent-marking.h" |
| |
| #include <stack> |
| #include <unordered_map> |
| |
| #include "include/v8config.h" |
| #include "src/base/template-utils.h" |
| #include "src/heap/gc-tracer.h" |
| #include "src/heap/heap-inl.h" |
| #include "src/heap/heap.h" |
| #include "src/heap/mark-compact-inl.h" |
| #include "src/heap/mark-compact.h" |
| #include "src/heap/marking.h" |
| #include "src/heap/objects-visiting-inl.h" |
| #include "src/heap/objects-visiting.h" |
| #include "src/heap/worklist.h" |
| #include "src/isolate.h" |
| #include "src/objects/hash-table-inl.h" |
| #include "src/objects/slots-inl.h" |
| #include "src/utils-inl.h" |
| #include "src/utils.h" |
| #include "src/v8.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| class ConcurrentMarkingState final |
| : public MarkingStateBase<ConcurrentMarkingState, AccessMode::ATOMIC> { |
| public: |
| explicit ConcurrentMarkingState(LiveBytesMap* live_bytes) |
| : live_bytes_(live_bytes) {} |
| |
| Bitmap* bitmap(const MemoryChunk* chunk) { |
| DCHECK_EQ(reinterpret_cast<intptr_t>(&chunk->marking_bitmap_) - |
| reinterpret_cast<intptr_t>(chunk), |
| MemoryChunk::kMarkBitmapOffset); |
| return chunk->marking_bitmap_; |
| } |
| |
| void IncrementLiveBytes(MemoryChunk* chunk, intptr_t by) { |
| (*live_bytes_)[chunk] += by; |
| } |
| |
| // The live_bytes and SetLiveBytes methods of the marking state are |
| // not used by the concurrent marker. |
| |
| private: |
| LiveBytesMap* live_bytes_; |
| }; |
| |
| // Helper class for storing in-object slot addresses and values. |
| class SlotSnapshot { |
| public: |
| SlotSnapshot() : number_of_slots_(0) {} |
| int number_of_slots() const { return number_of_slots_; } |
| ObjectSlot slot(int i) const { return snapshot_[i].first; } |
| Object* value(int i) const { return snapshot_[i].second; } |
| void clear() { number_of_slots_ = 0; } |
| void add(ObjectSlot slot, Object* value) { |
| snapshot_[number_of_slots_].first = slot; |
| snapshot_[number_of_slots_].second = value; |
| ++number_of_slots_; |
| } |
| |
| private: |
| static const int kMaxSnapshotSize = JSObject::kMaxInstanceSize / kPointerSize; |
| int number_of_slots_; |
| std::pair<ObjectSlot, Object*> snapshot_[kMaxSnapshotSize]; |
| DISALLOW_COPY_AND_ASSIGN(SlotSnapshot); |
| }; |
| |
| class ConcurrentMarkingVisitor final |
| : public HeapVisitor<int, ConcurrentMarkingVisitor> { |
| public: |
| using BaseClass = HeapVisitor<int, ConcurrentMarkingVisitor>; |
| |
| explicit ConcurrentMarkingVisitor( |
| ConcurrentMarking::MarkingWorklist* shared, |
| ConcurrentMarking::MarkingWorklist* bailout, LiveBytesMap* live_bytes, |
| WeakObjects* weak_objects, |
| ConcurrentMarking::EmbedderTracingWorklist* embedder_objects, int task_id, |
| bool embedder_tracing_enabled) |
| : shared_(shared, task_id), |
| bailout_(bailout, task_id), |
| weak_objects_(weak_objects), |
| embedder_objects_(embedder_objects, task_id), |
| marking_state_(live_bytes), |
| task_id_(task_id), |
| embedder_tracing_enabled_(embedder_tracing_enabled) {} |
| |
| template <typename T, typename = typename std::enable_if< |
| std::is_base_of<Object, T>::value>::type> |
| static V8_INLINE T* Cast(HeapObject* object) { |
| return T::cast(object); |
| } |
| |
| template <typename T, typename = typename std::enable_if< |
| std::is_base_of<ObjectPtr, T>::value>::type> |
| static V8_INLINE T Cast(HeapObject* object) { |
| return T::cast(object); |
| } |
| |
| bool ShouldVisit(HeapObject* object) { |
| return marking_state_.GreyToBlack(object); |
| } |
| |
| bool AllowDefaultJSObjectVisit() { return false; } |
| |
| void ProcessStrongHeapObject(HeapObject* host, ObjectSlot slot, |
| HeapObject* heap_object) { |
| MarkObject(heap_object); |
| MarkCompactCollector::RecordSlot(host, slot, heap_object); |
| } |
| |
| void ProcessWeakHeapObject(HeapObject* host, HeapObjectSlot slot, |
| HeapObject* heap_object) { |
| #ifdef THREAD_SANITIZER |
| // Perform a dummy acquire load to tell TSAN that there is no data race |
| // in mark-bit initialization. See MemoryChunk::Initialize for the |
| // corresponding release store. |
| MemoryChunk* chunk = MemoryChunk::FromAddress(heap_object->address()); |
| CHECK_NOT_NULL(chunk->synchronized_heap()); |
| #endif |
| if (marking_state_.IsBlackOrGrey(heap_object)) { |
| // Weak references with live values are directly processed here to |
| // reduce the processing time of weak cells during the main GC |
| // pause. |
| MarkCompactCollector::RecordSlot(host, slot, heap_object); |
| } else { |
| // If we do not know about liveness of the value, we have to process |
| // the reference when we know the liveness of the whole transitive |
| // closure. |
| weak_objects_->weak_references.Push(task_id_, std::make_pair(host, slot)); |
| } |
| } |
| |
| void VisitPointers(HeapObject* host, ObjectSlot start, |
| ObjectSlot end) override { |
| for (ObjectSlot slot = start; slot < end; ++slot) { |
| Object* object = slot.Relaxed_Load(); |
| DCHECK(!HasWeakHeapObjectTag(object)); |
| if (object->IsHeapObject()) { |
| ProcessStrongHeapObject(host, slot, HeapObject::cast(object)); |
| } |
| } |
| } |
| |
| void VisitPointers(HeapObject* host, MaybeObjectSlot start, |
| MaybeObjectSlot end) override { |
| for (MaybeObjectSlot slot = start; slot < end; ++slot) { |
| MaybeObject object = slot.Relaxed_Load(); |
| HeapObject* heap_object; |
| if (object->GetHeapObjectIfStrong(&heap_object)) { |
| // If the reference changes concurrently from strong to weak, the write |
| // barrier will treat the weak reference as strong, so we won't miss the |
| // weak reference. |
| ProcessStrongHeapObject(host, ObjectSlot(slot), heap_object); |
| } else if (object->GetHeapObjectIfWeak(&heap_object)) { |
| ProcessWeakHeapObject(host, HeapObjectSlot(slot), heap_object); |
| } |
| } |
| } |
| |
| // Weak list pointers should be ignored during marking. The lists are |
| // reconstructed after GC. |
| void VisitCustomWeakPointers(HeapObject* host, ObjectSlot start, |
| ObjectSlot end) override {} |
| |
| void VisitPointersInSnapshot(HeapObject* host, const SlotSnapshot& snapshot) { |
| for (int i = 0; i < snapshot.number_of_slots(); i++) { |
| ObjectSlot slot = snapshot.slot(i); |
| Object* object = snapshot.value(i); |
| DCHECK(!HasWeakHeapObjectTag(object)); |
| if (!object->IsHeapObject()) continue; |
| HeapObject* heap_object = HeapObject::cast(object); |
| MarkObject(heap_object); |
| MarkCompactCollector::RecordSlot(host, slot, heap_object); |
| } |
| } |
| |
| // =========================================================================== |
| // JS object ================================================================= |
| // =========================================================================== |
| |
| int VisitJSObject(Map map, JSObject* object) { |
| return VisitJSObjectSubclass(map, object); |
| } |
| |
| int VisitJSObjectFast(Map map, JSObject* object) { |
| return VisitJSObjectSubclass(map, object); |
| } |
| |
| int VisitWasmInstanceObject(Map map, WasmInstanceObject* object) { |
| return VisitJSObjectSubclass(map, object); |
| } |
| |
| int VisitJSWeakCell(Map map, JSWeakCell* weak_cell) { |
| int size = VisitJSObjectSubclass(map, weak_cell); |
| if (size == 0) { |
| return 0; |
| } |
| |
| if (weak_cell->target()->IsHeapObject()) { |
| HeapObject* target = HeapObject::cast(weak_cell->target()); |
| if (marking_state_.IsBlackOrGrey(target)) { |
| // Record the slot inside the JSWeakCell, since the |
| // VisitJSObjectSubclass above didn't visit it. |
| ObjectSlot slot = |
| HeapObject::RawField(weak_cell, JSWeakCell::kTargetOffset); |
| MarkCompactCollector::RecordSlot(weak_cell, slot, target); |
| } else { |
| // JSWeakCell points to a potentially dead object. We have to process |
| // them when we know the liveness of the whole transitive closure. |
| weak_objects_->js_weak_cells.Push(task_id_, weak_cell); |
| } |
| } |
| return size; |
| } |
| |
| // Some JS objects can carry back links to embedders that contain information |
| // relevant to the garbage collectors. |
| |
| int VisitJSApiObject(Map map, JSObject* object) { |
| return VisitEmbedderTracingSubclass(map, object); |
| } |
| |
| int VisitJSArrayBuffer(Map map, JSArrayBuffer* object) { |
| return VisitEmbedderTracingSubclass(map, object); |
| } |
| |
| int VisitJSDataView(Map map, JSDataView* object) { |
| return VisitEmbedderTracingSubclass(map, object); |
| } |
| |
| int VisitJSTypedArray(Map map, JSTypedArray* object) { |
| return VisitEmbedderTracingSubclass(map, object); |
| } |
| |
| // =========================================================================== |
| // Strings with pointers ===================================================== |
| // =========================================================================== |
| |
| int VisitConsString(Map map, ConsString* object) { |
| int size = ConsString::BodyDescriptor::SizeOf(map, object); |
| return VisitWithSnapshot(map, object, size, size); |
| } |
| |
| int VisitSlicedString(Map map, SlicedString* object) { |
| int size = SlicedString::BodyDescriptor::SizeOf(map, object); |
| return VisitWithSnapshot(map, object, size, size); |
| } |
| |
| int VisitThinString(Map map, ThinString* object) { |
| int size = ThinString::BodyDescriptor::SizeOf(map, object); |
| return VisitWithSnapshot(map, object, size, size); |
| } |
| |
| // =========================================================================== |
| // Strings without pointers ================================================== |
| // =========================================================================== |
| |
| int VisitSeqOneByteString(Map map, SeqOneByteString* object) { |
| int size = SeqOneByteString::SizeFor(object->synchronized_length()); |
| if (!ShouldVisit(object)) return 0; |
| VisitMapPointer(object, object->map_slot()); |
| return size; |
| } |
| |
| int VisitSeqTwoByteString(Map map, SeqTwoByteString* object) { |
| int size = SeqTwoByteString::SizeFor(object->synchronized_length()); |
| if (!ShouldVisit(object)) return 0; |
| VisitMapPointer(object, object->map_slot()); |
| return size; |
| } |
| |
| // =========================================================================== |
| // Fixed array object ======================================================== |
| // =========================================================================== |
| |
| int VisitFixedArray(Map map, FixedArray* object) { |
| return VisitLeftTrimmableArray(map, object); |
| } |
| |
| int VisitFixedDoubleArray(Map map, FixedDoubleArray object) { |
| return VisitLeftTrimmableArray(map, object); |
| } |
| |
| // =========================================================================== |
| // Code object =============================================================== |
| // =========================================================================== |
| |
| int VisitCode(Map map, Code object) { |
| bailout_.Push(object); |
| return 0; |
| } |
| |
| // =========================================================================== |
| // Side-effectful visitation. |
| // =========================================================================== |
| |
| int VisitBytecodeArray(Map map, BytecodeArray object) { |
| if (!ShouldVisit(object)) return 0; |
| int size = BytecodeArray::BodyDescriptor::SizeOf(map, object); |
| VisitMapPointer(object, object->map_slot()); |
| BytecodeArray::BodyDescriptor::IterateBody(map, object, size, this); |
| object->MakeOlder(); |
| return size; |
| } |
| |
| int VisitMap(Map meta_map, Map map) { |
| if (marking_state_.IsGrey(map)) { |
| // Maps have ad-hoc weakness for descriptor arrays. They also clear the |
| // code-cache. Conservatively visit strong fields skipping the |
| // descriptor array field and the code cache field. |
| VisitMapPointer(map, map->map_slot()); |
| VisitPointer(map, HeapObject::RawField(map, Map::kPrototypeOffset)); |
| VisitPointer( |
| map, HeapObject::RawField(map, Map::kConstructorOrBackPointerOffset)); |
| VisitPointer(map, HeapObject::RawMaybeWeakField( |
| map, Map::kTransitionsOrPrototypeInfoOffset)); |
| VisitPointer(map, HeapObject::RawField(map, Map::kDependentCodeOffset)); |
| bailout_.Push(map); |
| } |
| return 0; |
| } |
| |
| int VisitTransitionArray(Map map, TransitionArray* array) { |
| if (!ShouldVisit(array)) return 0; |
| VisitMapPointer(array, array->map_slot()); |
| int size = TransitionArray::BodyDescriptor::SizeOf(map, array); |
| TransitionArray::BodyDescriptor::IterateBody(map, array, size, this); |
| weak_objects_->transition_arrays.Push(task_id_, array); |
| return size; |
| } |
| |
| int VisitJSWeakCollection(Map map, JSWeakCollection* object) { |
| return VisitJSObjectSubclass(map, object); |
| } |
| |
| int VisitEphemeronHashTable(Map map, EphemeronHashTable table) { |
| if (!ShouldVisit(table)) return 0; |
| weak_objects_->ephemeron_hash_tables.Push(task_id_, table); |
| |
| for (int i = 0; i < table->Capacity(); i++) { |
| ObjectSlot key_slot = |
| table->RawFieldOfElementAt(EphemeronHashTable::EntryToIndex(i)); |
| HeapObject* key = HeapObject::cast(table->KeyAt(i)); |
| MarkCompactCollector::RecordSlot(table, key_slot, key); |
| |
| ObjectSlot value_slot = |
| table->RawFieldOfElementAt(EphemeronHashTable::EntryToValueIndex(i)); |
| |
| if (marking_state_.IsBlackOrGrey(key)) { |
| VisitPointer(table, value_slot); |
| |
| } else { |
| Object* value_obj = table->ValueAt(i); |
| |
| if (value_obj->IsHeapObject()) { |
| HeapObject* value = HeapObject::cast(value_obj); |
| MarkCompactCollector::RecordSlot(table, value_slot, value); |
| |
| // Revisit ephemerons with both key and value unreachable at end |
| // of concurrent marking cycle. |
| if (marking_state_.IsWhite(value)) { |
| weak_objects_->discovered_ephemerons.Push(task_id_, |
| Ephemeron{key, value}); |
| } |
| } |
| } |
| } |
| |
| return table->SizeFromMap(map); |
| } |
| |
| // Implements ephemeron semantics: Marks value if key is already reachable. |
| // Returns true if value was actually marked. |
| bool VisitEphemeron(HeapObject* key, HeapObject* value) { |
| if (marking_state_.IsBlackOrGrey(key)) { |
| if (marking_state_.WhiteToGrey(value)) { |
| shared_.Push(value); |
| return true; |
| } |
| |
| } else if (marking_state_.IsWhite(value)) { |
| weak_objects_->next_ephemerons.Push(task_id_, Ephemeron{key, value}); |
| } |
| |
| return false; |
| } |
| |
| void MarkObject(HeapObject* object) { |
| #ifdef THREAD_SANITIZER |
| // Perform a dummy acquire load to tell TSAN that there is no data race |
| // in mark-bit initialization. See MemoryChunk::Initialize for the |
| // corresponding release store. |
| MemoryChunk* chunk = MemoryChunk::FromAddress(object->address()); |
| CHECK_NOT_NULL(chunk->synchronized_heap()); |
| #endif |
| if (marking_state_.WhiteToGrey(object)) { |
| shared_.Push(object); |
| } |
| } |
| |
| private: |
| // Helper class for collecting in-object slot addresses and values. |
| class SlotSnapshottingVisitor final : public ObjectVisitor { |
| public: |
| explicit SlotSnapshottingVisitor(SlotSnapshot* slot_snapshot) |
| : slot_snapshot_(slot_snapshot) { |
| slot_snapshot_->clear(); |
| } |
| |
| void VisitPointers(HeapObject* host, ObjectSlot start, |
| ObjectSlot end) override { |
| for (ObjectSlot p = start; p < end; ++p) { |
| Object* object = p.Relaxed_Load(); |
| slot_snapshot_->add(p, object); |
| } |
| } |
| |
| void VisitPointers(HeapObject* host, MaybeObjectSlot start, |
| MaybeObjectSlot end) override { |
| // This should never happen, because we don't use snapshotting for objects |
| // which contain weak references. |
| UNREACHABLE(); |
| } |
| |
| void VisitCustomWeakPointers(HeapObject* host, ObjectSlot start, |
| ObjectSlot end) override { |
| DCHECK(host->IsJSWeakCell()); |
| } |
| |
| private: |
| SlotSnapshot* slot_snapshot_; |
| }; |
| |
| template <typename T> |
| int VisitJSObjectSubclass(Map map, T* object) { |
| int size = T::BodyDescriptor::SizeOf(map, object); |
| int used_size = map->UsedInstanceSize(); |
| DCHECK_LE(used_size, size); |
| DCHECK_GE(used_size, T::kHeaderSize); |
| return VisitWithSnapshot(map, object, used_size, size); |
| } |
| |
| template <typename T> |
| int VisitEmbedderTracingSubclass(Map map, T* object) { |
| DCHECK(object->IsApiWrapper()); |
| int size = VisitJSObjectSubclass(map, object); |
| if (size && embedder_tracing_enabled_) { |
| // Success: The object needs to be processed for embedder references on |
| // the main thread. |
| embedder_objects_.Push(object); |
| } |
| return size; |
| } |
| |
| template <typename T> |
| int VisitLeftTrimmableArray(Map map, T object) { |
| // The synchronized_length() function checks that the length is a Smi. |
| // This is not necessarily the case if the array is being left-trimmed. |
| Object* length = object->unchecked_synchronized_length(); |
| if (!ShouldVisit(object)) return 0; |
| // The cached length must be the actual length as the array is not black. |
| // Left trimming marks the array black before over-writing the length. |
| DCHECK(length->IsSmi()); |
| // TODO(3770): Drop std::remove_pointer after FixedArray* is migrated. |
| int size = std::remove_pointer<T>::type::SizeFor(Smi::ToInt(length)); |
| VisitMapPointer(object, object->map_slot()); |
| // TODO(3770): Drop std::remove_pointer after FixedArray* is migrated. |
| std::remove_pointer<T>::type::BodyDescriptor::IterateBody(map, object, size, |
| this); |
| return size; |
| } |
| |
| template <typename T> |
| int VisitWithSnapshot(Map map, T* object, int used_size, int size) { |
| const SlotSnapshot& snapshot = MakeSlotSnapshot(map, object, used_size); |
| if (!ShouldVisit(object)) return 0; |
| VisitPointersInSnapshot(object, snapshot); |
| return size; |
| } |
| |
| template <typename T> |
| const SlotSnapshot& MakeSlotSnapshot(Map map, T* object, int size) { |
| SlotSnapshottingVisitor visitor(&slot_snapshot_); |
| visitor.VisitPointer(object, ObjectSlot(object->map_slot().address())); |
| T::BodyDescriptor::IterateBody(map, object, size, &visitor); |
| return slot_snapshot_; |
| } |
| |
| ConcurrentMarking::MarkingWorklist::View shared_; |
| ConcurrentMarking::MarkingWorklist::View bailout_; |
| WeakObjects* weak_objects_; |
| ConcurrentMarking::EmbedderTracingWorklist::View embedder_objects_; |
| ConcurrentMarkingState marking_state_; |
| int task_id_; |
| SlotSnapshot slot_snapshot_; |
| bool embedder_tracing_enabled_; |
| }; |
| |
| // Strings can change maps due to conversion to thin string or external strings. |
| // Use reinterpret cast to avoid data race in slow dchecks. |
| template <> |
| ConsString* ConcurrentMarkingVisitor::Cast(HeapObject* object) { |
| return reinterpret_cast<ConsString*>(object); |
| } |
| |
| template <> |
| SlicedString* ConcurrentMarkingVisitor::Cast(HeapObject* object) { |
| return reinterpret_cast<SlicedString*>(object); |
| } |
| |
| template <> |
| ThinString* ConcurrentMarkingVisitor::Cast(HeapObject* object) { |
| return reinterpret_cast<ThinString*>(object); |
| } |
| |
| template <> |
| SeqOneByteString* ConcurrentMarkingVisitor::Cast(HeapObject* object) { |
| return reinterpret_cast<SeqOneByteString*>(object); |
| } |
| |
| template <> |
| SeqTwoByteString* ConcurrentMarkingVisitor::Cast(HeapObject* object) { |
| return reinterpret_cast<SeqTwoByteString*>(object); |
| } |
| |
| // Fixed array can become a free space during left trimming. |
| template <> |
| FixedArray* ConcurrentMarkingVisitor::Cast(HeapObject* object) { |
| return reinterpret_cast<FixedArray*>(object); |
| } |
| |
| class ConcurrentMarking::Task : public CancelableTask { |
| public: |
| Task(Isolate* isolate, ConcurrentMarking* concurrent_marking, |
| TaskState* task_state, int task_id) |
| : CancelableTask(isolate), |
| concurrent_marking_(concurrent_marking), |
| task_state_(task_state), |
| task_id_(task_id) {} |
| |
| ~Task() override = default; |
| |
| private: |
| // v8::internal::CancelableTask overrides. |
| void RunInternal() override { |
| concurrent_marking_->Run(task_id_, task_state_); |
| } |
| |
| ConcurrentMarking* concurrent_marking_; |
| TaskState* task_state_; |
| int task_id_; |
| DISALLOW_COPY_AND_ASSIGN(Task); |
| }; |
| |
| ConcurrentMarking::ConcurrentMarking(Heap* heap, MarkingWorklist* shared, |
| MarkingWorklist* bailout, |
| MarkingWorklist* on_hold, |
| WeakObjects* weak_objects, |
| EmbedderTracingWorklist* embedder_objects) |
| : heap_(heap), |
| shared_(shared), |
| bailout_(bailout), |
| on_hold_(on_hold), |
| weak_objects_(weak_objects), |
| embedder_objects_(embedder_objects) { |
| // The runtime flag should be set only if the compile time flag was set. |
| #ifndef V8_CONCURRENT_MARKING |
| CHECK(!FLAG_concurrent_marking && !FLAG_parallel_marking); |
| #endif |
| } |
| |
| void ConcurrentMarking::Run(int task_id, TaskState* task_state) { |
| TRACE_BACKGROUND_GC(heap_->tracer(), |
| GCTracer::BackgroundScope::MC_BACKGROUND_MARKING); |
| size_t kBytesUntilInterruptCheck = 64 * KB; |
| int kObjectsUntilInterrupCheck = 1000; |
| ConcurrentMarkingVisitor visitor( |
| shared_, bailout_, &task_state->live_bytes, weak_objects_, |
| embedder_objects_, task_id, heap_->local_embedder_heap_tracer()->InUse()); |
| double time_ms; |
| size_t marked_bytes = 0; |
| if (FLAG_trace_concurrent_marking) { |
| heap_->isolate()->PrintWithTimestamp( |
| "Starting concurrent marking task %d\n", task_id); |
| } |
| bool ephemeron_marked = false; |
| |
| { |
| TimedScope scope(&time_ms); |
| |
| { |
| Ephemeron ephemeron; |
| |
| while (weak_objects_->current_ephemerons.Pop(task_id, &ephemeron)) { |
| if (visitor.VisitEphemeron(ephemeron.key, ephemeron.value)) { |
| ephemeron_marked = true; |
| } |
| } |
| } |
| |
| bool done = false; |
| while (!done) { |
| size_t current_marked_bytes = 0; |
| int objects_processed = 0; |
| while (current_marked_bytes < kBytesUntilInterruptCheck && |
| objects_processed < kObjectsUntilInterrupCheck) { |
| HeapObject* object; |
| if (!shared_->Pop(task_id, &object)) { |
| done = true; |
| break; |
| } |
| objects_processed++; |
| // The order of the two loads is important. |
| Address new_space_top = heap_->new_space()->original_top_acquire(); |
| Address new_space_limit = heap_->new_space()->original_limit_relaxed(); |
| Address addr = object->address(); |
| if (new_space_top <= addr && addr < new_space_limit) { |
| on_hold_->Push(task_id, object); |
| } else { |
| Map map = object->synchronized_map(); |
| current_marked_bytes += visitor.Visit(map, object); |
| } |
| } |
| marked_bytes += current_marked_bytes; |
| base::AsAtomicWord::Relaxed_Store<size_t>(&task_state->marked_bytes, |
| marked_bytes); |
| if (task_state->preemption_request) { |
| TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.gc"), |
| "ConcurrentMarking::Run Preempted"); |
| break; |
| } |
| } |
| |
| if (done) { |
| Ephemeron ephemeron; |
| |
| while (weak_objects_->discovered_ephemerons.Pop(task_id, &ephemeron)) { |
| if (visitor.VisitEphemeron(ephemeron.key, ephemeron.value)) { |
| ephemeron_marked = true; |
| } |
| } |
| } |
| |
| shared_->FlushToGlobal(task_id); |
| bailout_->FlushToGlobal(task_id); |
| on_hold_->FlushToGlobal(task_id); |
| embedder_objects_->FlushToGlobal(task_id); |
| |
| weak_objects_->transition_arrays.FlushToGlobal(task_id); |
| weak_objects_->ephemeron_hash_tables.FlushToGlobal(task_id); |
| weak_objects_->current_ephemerons.FlushToGlobal(task_id); |
| weak_objects_->next_ephemerons.FlushToGlobal(task_id); |
| weak_objects_->discovered_ephemerons.FlushToGlobal(task_id); |
| weak_objects_->weak_references.FlushToGlobal(task_id); |
| weak_objects_->js_weak_cells.FlushToGlobal(task_id); |
| base::AsAtomicWord::Relaxed_Store<size_t>(&task_state->marked_bytes, 0); |
| total_marked_bytes_ += marked_bytes; |
| |
| if (ephemeron_marked) { |
| set_ephemeron_marked(true); |
| } |
| |
| { |
| base::MutexGuard guard(&pending_lock_); |
| is_pending_[task_id] = false; |
| --pending_task_count_; |
| pending_condition_.NotifyAll(); |
| } |
| } |
| if (FLAG_trace_concurrent_marking) { |
| heap_->isolate()->PrintWithTimestamp( |
| "Task %d concurrently marked %dKB in %.2fms\n", task_id, |
| static_cast<int>(marked_bytes / KB), time_ms); |
| } |
| } |
| |
| void ConcurrentMarking::ScheduleTasks() { |
| DCHECK(FLAG_parallel_marking || FLAG_concurrent_marking); |
| DCHECK(!heap_->IsTearingDown()); |
| base::MutexGuard guard(&pending_lock_); |
| DCHECK_EQ(0, pending_task_count_); |
| if (task_count_ == 0) { |
| static const int num_cores = |
| V8::GetCurrentPlatform()->NumberOfWorkerThreads() + 1; |
| #if defined(V8_OS_MACOSX) |
| // Mac OSX 10.11 and prior seems to have trouble when doing concurrent |
| // marking on competing hyper-threads (regresses Octane/Splay). As such, |
| // only use num_cores/2, leaving one of those for the main thread. |
| // TODO(ulan): Use all cores on Mac 10.12+. |
| task_count_ = Max(1, Min(kMaxTasks, (num_cores / 2) - 1)); |
| #else // defined(OS_MACOSX) |
| // On other platforms use all logical cores, leaving one for the main |
| // thread. |
| task_count_ = Max(1, Min(kMaxTasks, num_cores - 1)); |
| #endif // defined(OS_MACOSX) |
| } |
| // Task id 0 is for the main thread. |
| for (int i = 1; i <= task_count_; i++) { |
| if (!is_pending_[i]) { |
| if (FLAG_trace_concurrent_marking) { |
| heap_->isolate()->PrintWithTimestamp( |
| "Scheduling concurrent marking task %d\n", i); |
| } |
| task_state_[i].preemption_request = false; |
| is_pending_[i] = true; |
| ++pending_task_count_; |
| auto task = |
| base::make_unique<Task>(heap_->isolate(), this, &task_state_[i], i); |
| cancelable_id_[i] = task->id(); |
| V8::GetCurrentPlatform()->CallOnWorkerThread(std::move(task)); |
| } |
| } |
| DCHECK_EQ(task_count_, pending_task_count_); |
| } |
| |
| void ConcurrentMarking::RescheduleTasksIfNeeded() { |
| DCHECK(FLAG_parallel_marking || FLAG_concurrent_marking); |
| if (heap_->IsTearingDown()) return; |
| { |
| base::MutexGuard guard(&pending_lock_); |
| if (pending_task_count_ > 0) return; |
| } |
| if (!shared_->IsGlobalPoolEmpty() || |
| !weak_objects_->current_ephemerons.IsEmpty() || |
| !weak_objects_->discovered_ephemerons.IsEmpty()) { |
| ScheduleTasks(); |
| } |
| } |
| |
| bool ConcurrentMarking::Stop(StopRequest stop_request) { |
| DCHECK(FLAG_parallel_marking || FLAG_concurrent_marking); |
| base::MutexGuard guard(&pending_lock_); |
| |
| if (pending_task_count_ == 0) return false; |
| |
| if (stop_request != StopRequest::COMPLETE_TASKS_FOR_TESTING) { |
| CancelableTaskManager* task_manager = |
| heap_->isolate()->cancelable_task_manager(); |
| for (int i = 1; i <= task_count_; i++) { |
| if (is_pending_[i]) { |
| if (task_manager->TryAbort(cancelable_id_[i]) == |
| TryAbortResult::kTaskAborted) { |
| is_pending_[i] = false; |
| --pending_task_count_; |
| } else if (stop_request == StopRequest::PREEMPT_TASKS) { |
| task_state_[i].preemption_request = true; |
| } |
| } |
| } |
| } |
| while (pending_task_count_ > 0) { |
| pending_condition_.Wait(&pending_lock_); |
| } |
| for (int i = 1; i <= task_count_; i++) { |
| DCHECK(!is_pending_[i]); |
| } |
| return true; |
| } |
| |
| bool ConcurrentMarking::IsStopped() { |
| if (!FLAG_concurrent_marking) return true; |
| |
| base::MutexGuard guard(&pending_lock_); |
| return pending_task_count_ == 0; |
| } |
| |
| void ConcurrentMarking::FlushLiveBytes( |
| MajorNonAtomicMarkingState* marking_state) { |
| DCHECK_EQ(pending_task_count_, 0); |
| for (int i = 1; i <= task_count_; i++) { |
| LiveBytesMap& live_bytes = task_state_[i].live_bytes; |
| for (auto pair : live_bytes) { |
| // ClearLiveness sets the live bytes to zero. |
| // Pages with zero live bytes might be already unmapped. |
| if (pair.second != 0) { |
| marking_state->IncrementLiveBytes(pair.first, pair.second); |
| } |
| } |
| live_bytes.clear(); |
| task_state_[i].marked_bytes = 0; |
| } |
| total_marked_bytes_ = 0; |
| } |
| |
| void ConcurrentMarking::ClearLiveness(MemoryChunk* chunk) { |
| for (int i = 1; i <= task_count_; i++) { |
| if (task_state_[i].live_bytes.count(chunk)) { |
| task_state_[i].live_bytes[chunk] = 0; |
| } |
| } |
| } |
| |
| size_t ConcurrentMarking::TotalMarkedBytes() { |
| size_t result = 0; |
| for (int i = 1; i <= task_count_; i++) { |
| result += |
| base::AsAtomicWord::Relaxed_Load<size_t>(&task_state_[i].marked_bytes); |
| } |
| result += total_marked_bytes_; |
| return result; |
| } |
| |
| ConcurrentMarking::PauseScope::PauseScope(ConcurrentMarking* concurrent_marking) |
| : concurrent_marking_(concurrent_marking), |
| resume_on_exit_(FLAG_concurrent_marking && |
| concurrent_marking_->Stop( |
| ConcurrentMarking::StopRequest::PREEMPT_TASKS)) { |
| DCHECK_IMPLIES(resume_on_exit_, FLAG_concurrent_marking); |
| } |
| |
| ConcurrentMarking::PauseScope::~PauseScope() { |
| if (resume_on_exit_) concurrent_marking_->RescheduleTasksIfNeeded(); |
| } |
| |
| } // namespace internal |
| } // namespace v8 |