WARNING: ThreadSanitizer: data race (pid=18876)
  Atomic read of size 4 at 0x7e8a017bb344 by thread T3 (mutexes: write M0):
    #0 __cxx_atomic_load<int> buildtools/third_party/libc++/trunk/include/atomic:948:12 (d8+0xa91de9) (BuildId: 6011f09c007429d6)
    #1 load buildtools/third_party/libc++/trunk/include/atomic:1537:17 (d8+0xa91de9)
    #2 atomic_load_explicit<int> buildtools/third_party/libc++/trunk/include/atomic:1916:17 (d8+0xa91de9)
    #3 Relaxed_Load src/base/atomicops.h:237:10 (d8+0xa91de9)
    #4 Relaxed_Load<unsigned int> src/base/atomic-utils.h:87:9 (d8+0xa91de9)
    #5 Relaxed_Load src/objects/compressed-slots-inl.h:75:26 (d8+0xa91de9)
    #6 VisitPointer src/heap/sweeper.cc:674:50 (d8+0xa91de9)
    #7 VisitPointers src/heap/sweeper.cc:690:7 (d8+0xa91de9)
    #8 IteratePointers<v8::internal::(anonymous namespace)::PromotedPageRecordMigratedSlotVisitor> src/objects/objects-body-descriptors-inl.h:128:6 (d8+0xa91de9)
    #9 IterateBody<v8::internal::(anonymous namespace)::PromotedPageRecordMigratedSlotVisitor> src/objects/objects-body-descriptors.h:135:5 (d8+0xa91de9)
    #10 void v8::internal::CallIterateBody::apply<v8::internal::FixedArray::BodyDescriptor, v8::internal::(anonymous namespace)::PromotedPageRecordMigratedSlotVisitor>(v8::internal::Map, v8::internal::HeapObject, int, v8::internal::(anonymous namespace)::PromotedPageRecordMigratedSlotVisitor*) src/objects/objects-body-descriptors-inl.h:1432:5 (d8+0xa91de9)
    #11 auto v8::internal::BodyDescriptorApply<v8::internal::CallIterateBody, v8::internal::Map&, v8::internal::HeapObject&, int&, v8::internal::(anonymous namespace)::PromotedPageRecordMigratedSlotVisitor*&>(v8::internal::InstanceType, v8::internal::Map&, v8::internal::HeapObject&, int&, v8::internal::(anonymous namespace)::PromotedPageRecordMigratedSlotVisitor*&) src/objects/objects-body-descriptors-inl.h (d8+0xa910c4) (BuildId: 6011f09c007429d6)
    #12 IterateBodyFast<v8::internal::(anonymous namespace)::PromotedPageRecordMigratedSlotVisitor> src/objects/objects-body-descriptors-inl.h:1438:3 (d8+0xa8c512) (BuildId: 6011f09c007429d6)
    #13 IterateBodyFast<v8::internal::(anonymous namespace)::PromotedPageRecordMigratedSlotVisitor> src/objects/objects-body-descriptors-inl.h:1425:3 (d8+0xa8c512)
    #14 IterateFast<v8::internal::(anonymous namespace)::PromotedPageRecordMigratedSlotVisitor> src/objects/objects-body-descriptors-inl.h:1413:3 (d8+0xa8c512)
    #15 v8::internal::(anonymous namespace)::HandlePromotedObject(v8::internal::HeapObject, v8::internal::NonAtomicMarkingState*, v8::internal::PretenuringHandler*, v8::internal::PtrComprCageBase, std::Cr::unordered_map<v8::internal::AllocationSite, unsigned long, v8::internal::Object::Hasher, std::Cr::equal_to<v8::internal::AllocationSite>, std::Cr::allocator<std::Cr::pair<v8::internal::AllocationSite const, unsigned long>>>*, v8::internal::(anonymous namespace)::PromotedPageRecordMigratedSlotVisitor*) src/heap/sweeper.cc:801:10 (d8+0xa8c512)
    #16 v8::internal::Sweeper::RawIteratePromotedPageForRememberedSets(v8::internal::MemoryChunk*, std::Cr::unordered_map<v8::internal::AllocationSite, unsigned long, v8::internal::Object::Hasher, std::Cr::equal_to<v8::internal::AllocationSite>, std::Cr::allocator<std::Cr::pair<v8::internal::AllocationSite const, unsigned long>>>*, std::Cr::unordered_map<v8::internal::MemoryChunk*, v8::internal::SlotSet*, std::Cr::hash<v8::internal::MemoryChunk*>, std::Cr::equal_to<v8::internal::MemoryChunk*>, std::Cr::allocator<std::Cr::pair<v8::internal::MemoryChunk* const, v8::internal::SlotSet*>>>*) src/heap/sweeper.cc:837:7 (d8+0xa8c31b) (BuildId: 6011f09c007429d6)
    #17 ParallelIteratePromotedPageForRememberedSets src/heap/sweeper.cc:984:3 (d8+0xa992fc) (BuildId: 6011f09c007429d6)
    #18 v8::internal::Sweeper::ConcurrentSweeper::ConcurrentSweepForRememberedSet(v8::JobDelegate*) src/heap/sweeper.cc:60:17 (d8+0xa992fc)
    #19 v8::internal::Sweeper::SweeperJob::RunImpl(v8::JobDelegate*, bool) src/heap/sweeper.cc:125:31 (d8+0xa98416) (BuildId: 6011f09c007429d6)
    #20 v8::internal::Sweeper::SweeperJob::Run(v8::JobDelegate*) src/heap/sweeper.cc:97:5 (d8+0xa97a09) (BuildId: 6011f09c007429d6)
    #21 v8::platform::DefaultJobWorker::Run() src/libplatform/default-job.h:147:18 (d8+0x200c72b) (BuildId: 6011f09c007429d6)
    #22 v8::platform::DefaultWorkerThreadsTaskRunner::WorkerThread::Run() src/libplatform/default-worker-threads-task-runner.cc:73:11 (d8+0x2012240) (BuildId: 6011f09c007429d6)
    #23 NotifyStartedAndRun src/base/platform/platform.h:596:5 (d8+0x2006592) (BuildId: 6011f09c007429d6)
    #24 v8::base::ThreadEntry(void*) src/base/platform/platform-posix.cc:1123:11 (d8+0x2006592)

  Previous write of size 4 at 0x7e8a017bb344 by main thread:
    #0 __tsan_memcpy /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp:3105:3 (d8+0x564e00) (BuildId: 6011f09c007429d6)
    #1 MemCopy src/utils/memcopy.h (d8+0x95e3a0) (BuildId: 6011f09c007429d6)
    #2 void v8::internal::Heap::CopyRange<v8::internal::CompressedObjectSlot>(v8::internal::HeapObject, v8::internal::CompressedObjectSlot, v8::internal::CompressedObjectSlot, int, v8::internal::WriteBarrierMode) src/heap/heap.cc:2064:5 (d8+0x95e3a0)
    #3 CopyElements src/objects/fixed-array-inl.h:274:20 (d8+0xc0fb96) (BuildId: 6011f09c007429d6)
    #4 CopyObjectToObjectElements src/objects/elements.cc:228:6 (d8+0xc0fb96)
    #5 v8::internal::(anonymous namespace)::FastSmiOrObjectElementsAccessor<v8::internal::(anonymous namespace)::FastPackedObjectElementsAccessor, v8::internal::(anonymous namespace)::ElementsKindTraits<(v8::internal::ElementsKind)2>>::CopyElementsImpl(v8::internal::Isolate*, v8::internal::FixedArrayBase, unsigned int, v8::internal::FixedArrayBase, v8::internal::ElementsKind, unsigned int, int, int) src/objects/elements.cc:2566:9 (d8+0xc0fb96)
    #6 v8::internal::(anonymous namespace)::ElementsAccessorBase<v8::internal::(anonymous namespace)::FastPackedObjectElementsAccessor, v8::internal::(anonymous namespace)::ElementsKindTraits<(v8::internal::ElementsKind)2>>::CopyElements(v8::internal::JSObject, unsigned int, v8::internal::ElementsKind, v8::internal::Handle<v8::internal::FixedArrayBase>, unsigned int, int) src/objects/elements.cc:1045:5 (d8+0xc0f00a) (BuildId: 6011f09c007429d6)
    #7 v8::internal::ElementsAccessor::Concat(v8::internal::Isolate*, v8::internal::BuiltinArguments*, unsigned int, unsigned int) src/objects/elements.cc:5424:15 (d8+0xbfcd07) (BuildId: 6011f09c007429d6)
    #8 v8::internal::(anonymous namespace)::Fast_ArrayConcat(v8::internal::Isolate*, v8::internal::BuiltinArguments*) src/builtins/builtins-array.cc:1509:10 (d8+0x68def0) (BuildId: 6011f09c007429d6)
    #9 v8::internal::Builtin_Impl_ArrayConcat(v8::internal::BuiltinArguments, v8::internal::Isolate*) src/builtins/builtins-array.cc:1531:9 (d8+0x686e5e) (BuildId: 6011f09c007429d6)
    #10 v8::internal::Builtin_ArrayConcat(int, unsigned long*, v8::internal::Isolate*) src/builtins/builtins-array.cc:1515:1 (d8+0x686783) (BuildId: 6011f09c007429d6)
    #11 Builtins_AsyncFromSyncIteratorPrototypeThrow setup-isolate-deserialize.cc (d8+0x1dcd837)
    #12 v8::internal::Execution::CallScript(v8::internal::Isolate*, v8::internal::Handle<v8::internal::JSFunction>, v8::internal::Handle<v8::internal::Object>, v8::internal::Handle<v8::internal::Object>) src/execution/execution.cc:538:10 (d8+0x85ba40) (BuildId: 6011f09c007429d6)
    #13 v8::Script::Run(v8::Local<v8::Context>, v8::Local<v8::Data>) src/api/api.cc:2271:7 (d8+0x602527) (BuildId: 6011f09c007429d6)
    #14 v8::Script::Run(v8::Local<v8::Context>) src/api/api.cc:2198:10 (d8+0x601ce0) (BuildId: 6011f09c007429d6)
    #15 v8::Shell::ExecuteString(v8::Isolate*, v8::Local<v8::String>, v8::Local<v8::String>, v8::Shell::PrintResult, v8::Shell::ReportExceptions, v8::Shell::ProcessMessageQueue) src/d8/d8.cc:876:28 (d8+0x5bf3d6) (BuildId: 6011f09c007429d6)
    #16 v8::SourceGroup::Execute(v8::Isolate*) src/d8/d8.cc:4483:10 (d8+0x5d90d3) (BuildId: 6011f09c007429d6)
    #17 v8::Shell::RunMain(v8::Isolate*, bool) src/d8/d8.cc:5217:39 (d8+0x5dd08e) (BuildId: 6011f09c007429d6)
    #18 v8::Shell::Main(int, char**) src/d8/d8.cc:6013:18 (d8+0x5df876) (BuildId: 6011f09c007429d6)
    #19 main src/d8/d8.cc:6110:43 (d8+0x5dfe80) (BuildId: 6011f09c007429d6)

  Mutex M0 (0x7b0c00005670) created at:
    #0 pthread_mutex_init /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp:1331:3 (d8+0x522300) (BuildId: 6011f09c007429d6)
    #1 InitializeNativeHandle src/base/platform/mutex.cc:99:12 (d8+0x1ffe32b) (BuildId: 6011f09c007429d6)
    #2 v8::base::Mutex::Mutex() src/base/platform/mutex.cc:152:3 (d8+0x1ffe32b)
    #3 v8::internal::MemoryChunk::MemoryChunk(v8::internal::Heap*, v8::internal::BaseSpace*, unsigned long, unsigned long, unsigned long, v8::internal::VirtualMemory, v8::internal::Executability, v8::internal::PageSize) src/heap/memory-chunk.cc:154:16 (d8+0xa30b9f) (BuildId: 6011f09c007429d6)
    #4 v8::internal::Page::Page(v8::internal::Heap*, v8::internal::BaseSpace*, unsigned long, unsigned long, unsigned long, v8::internal::VirtualMemory, v8::internal::Executability) src/heap/spaces.cc:53:7 (d8+0xa83b0f) (BuildId: 6011f09c007429d6)
    #5 v8::internal::MemoryAllocator::AllocatePage(v8::internal::MemoryAllocator::AllocationMode, v8::internal::Space*, v8::internal::Executability) src/heap/memory-allocator.cc:579:40 (d8+0xa2d794) (BuildId: 6011f09c007429d6)
    #6 v8::internal::PagedSpaceBase::TryExpandImpl() src/heap/paged-spaces.cc:393:44 (d8+0xa4c858) (BuildId: 6011f09c007429d6)
    #7 PreallocatePages src/heap/new-spaces.cc:984:10 (d8+0xa3d952) (BuildId: 6011f09c007429d6)
    #8 EnsureCurrentCapacity src/heap/new-spaces.cc:995:10 (d8+0xa3d952)
    #9 v8::internal::PagedNewSpace::EnsureCurrentCapacity() src/heap/new-spaces.h:790:25 (d8+0xa3d952)
    #10 v8::internal::MinorMarkCompactCollector::Finish() src/heap/mark-compact.cc:6041:31 (d8+0x9d3018) (BuildId: 6011f09c007429d6)
    #11 v8::internal::MinorMarkCompactCollector::CollectGarbage() src/heap/mark-compact.cc:6076:3 (d8+0x9d41f9) (BuildId: 6011f09c007429d6)
    #12 v8::internal::Heap::MinorMarkCompact() src/heap/heap.cc:2600:34 (d8+0x9491ad) (BuildId: 6011f09c007429d6)
    #13 v8::internal::Heap::PerformGarbageCollection(v8::internal::GarbageCollector, v8::internal::GarbageCollectionReason, char const*) src/heap/heap.cc:2258:5 (d8+0x942350) (BuildId: 6011f09c007429d6)
    #14 v8::internal::Heap::CollectGarbage(v8::internal::AllocationSpace, v8::internal::GarbageCollectionReason, v8::GCCallbackFlags) src/heap/heap.cc:1714:13 (d8+0x93d77e) (BuildId: 6011f09c007429d6)
    #15 v8::internal::HeapAllocator::AllocateRawWithLightRetrySlowPath(int, v8::internal::AllocationType, v8::internal::AllocationOrigin, v8::internal::AllocationAlignment) src/heap/heap-allocator.cc:95:14 (d8+0x92c626) (BuildId: 6011f09c007429d6)
    #16 v8::internal::HeapAllocator::AllocateRawWithRetryOrFailSlowPath(int, v8::internal::AllocationType, v8::internal::AllocationOrigin, v8::internal::AllocationAlignment) src/heap/heap-allocator.cc:110:7 (d8+0x92d73e) (BuildId: 6011f09c007429d6)
    #17 AllocateRawWith<(v8::internal::HeapAllocator::AllocationRetryMode)1> src/heap/heap-allocator-inl.h:237:16 (d8+0x8fe787) (BuildId: 6011f09c007429d6)
    #18 v8::internal::Factory::AllocateRaw(int, v8::internal::AllocationType, v8::internal::AllocationAlignment) src/heap/factory.cc:327:23 (d8+0x8fe787)
    #19 AllocateRaw src/heap/factory-base.cc:1141:18 (d8+0x8f0283) (BuildId: 6011f09c007429d6)
    #20 AllocateRawArray src/heap/factory-base.cc:1088:23 (d8+0x8f0283)
    #21 AllocateRawFixedArray src/heap/factory-base.cc:1105:10 (d8+0x8f0283)
    #22 v8::internal::FactoryBase<v8::internal::Factory>::NewFixedArrayWithFiller(v8::internal::Handle<v8::internal::Map>, int, v8::internal::Handle<v8::internal::Oddball>, v8::internal::AllocationType) src/heap/factory-base.cc:130:23 (d8+0x8f0283)
    #23 v8::internal::FactoryBase<v8::internal::Factory>::NewFixedArray(int, v8::internal::AllocationType) src/heap/factory-base.cc:101:10 (d8+0x8f01f6) (BuildId: 6011f09c007429d6)
    #24 NewJSArrayStorage src/heap/factory.cc:2829:14 (d8+0x9139ca) (BuildId: 6011f09c007429d6)
    #25 v8::internal::Factory::NewJSArray(v8::internal::ElementsKind, int, int, v8::internal::ArrayStorageAllocationMode, v8::internal::AllocationType) src/heap/factory.cc:2728:7 (d8+0x9139ca)
    #26 v8::internal::ElementsAccessor::Concat(v8::internal::Isolate*, v8::internal::BuiltinArguments*, unsigned int, unsigned int) src/objects/elements.cc:5409:54 (d8+0xbfcaaa) (BuildId: 6011f09c007429d6)
    #27 v8::internal::(anonymous namespace)::Fast_ArrayConcat(v8::internal::Isolate*, v8::internal::BuiltinArguments*) src/builtins/builtins-array.cc:1509:10 (d8+0x68def0) (BuildId: 6011f09c007429d6)
    #28 v8::internal::Builtin_Impl_ArrayConcat(v8::internal::BuiltinArguments, v8::internal::Isolate*) src/builtins/builtins-array.cc:1531:9 (d8+0x686e5e) (BuildId: 6011f09c007429d6)
    #29 v8::internal::Builtin_ArrayConcat(int, unsigned long*, v8::internal::Isolate*) src/builtins/builtins-array.cc:1515:1 (d8+0x686783) (BuildId: 6011f09c007429d6)
    #30 Builtins_AsyncFromSyncIteratorPrototypeThrow setup-isolate-deserialize.cc (d8+0x1dcd837)
    #31 v8::internal::Execution::CallScript(v8::internal::Isolate*, v8::internal::Handle<v8::internal::JSFunction>, v8::internal::Handle<v8::internal::Object>, v8::internal::Handle<v8::internal::Object>) src/execution/execution.cc:538:10 (d8+0x85ba40) (BuildId: 6011f09c007429d6)
    #32 v8::Script::Run(v8::Local<v8::Context>, v8::Local<v8::Data>) src/api/api.cc:2271:7 (d8+0x602527) (BuildId: 6011f09c007429d6)
    #33 v8::Script::Run(v8::Local<v8::Context>) src/api/api.cc:2198:10 (d8+0x601ce0) (BuildId: 6011f09c007429d6)
    #34 v8::Shell::ExecuteString(v8::Isolate*, v8::Local<v8::String>, v8::Local<v8::String>, v8::Shell::PrintResult, v8::Shell::ReportExceptions, v8::Shell::ProcessMessageQueue) src/d8/d8.cc:876:28 (d8+0x5bf3d6) (BuildId: 6011f09c007429d6)
    #35 v8::SourceGroup::Execute(v8::Isolate*) src/d8/d8.cc:4483:10 (d8+0x5d90d3) (BuildId: 6011f09c007429d6)
    #36 v8::Shell::RunMain(v8::Isolate*, bool) src/d8/d8.cc:5217:39 (d8+0x5dd08e) (BuildId: 6011f09c007429d6)
    #37 v8::Shell::Main(int, char**) src/d8/d8.cc:6013:18 (d8+0x5df876) (BuildId: 6011f09c007429d6)
    #38 main src/d8/d8.cc:6110:43 (d8+0x5dfe80) (BuildId: 6011f09c007429d6)

  Thread T3 'V8 DefaultWorke' (tid=18881, running) created by main thread at:
    #0 pthread_create /b/s/w/ir/cache/builder/src/third_party/llvm/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp:1038:3 (d8+0x52098b) (BuildId: 6011f09c007429d6)
    #1 v8::base::Thread::Start() src/base/platform/platform-posix.cc:1155:14 (d8+0x20064a6) (BuildId: 6011f09c007429d6)
    #2 WorkerThread src/libplatform/default-worker-threads-task-runner.cc:66:3 (d8+0x2011c07) (BuildId: 6011f09c007429d6)
    #3 make_unique<v8::platform::DefaultWorkerThreadsTaskRunner::WorkerThread, v8::platform::DefaultWorkerThreadsTaskRunner *> buildtools/third_party/libc++/trunk/include/__memory/unique_ptr.h:686:30 (d8+0x2011c07)
    #4 v8::platform::DefaultWorkerThreadsTaskRunner::DefaultWorkerThreadsTaskRunner(unsigned int, double (*)()) src/libplatform/default-worker-threads-task-runner.cc:16:28 (d8+0x2011c07)
    #5 construct_at<v8::platform::DefaultWorkerThreadsTaskRunner, const int &, double (*)(), v8::platform::DefaultWorkerThreadsTaskRunner *> buildtools/third_party/libc++/trunk/include/__memory/construct_at.h:38:48 (d8+0x2008d60) (BuildId: 6011f09c007429d6)
    #6 construct<v8::platform::DefaultWorkerThreadsTaskRunner, const int &, double (*)(), void, void> buildtools/third_party/libc++/trunk/include/__memory/allocator_traits.h:304:9 (d8+0x2008d60)
    #7 __shared_ptr_emplace<const int &, double (*)()> buildtools/third_party/libc++/trunk/include/__memory/shared_ptr.h:275:9 (d8+0x2008d60)
    #8 allocate_shared<v8::platform::DefaultWorkerThreadsTaskRunner, std::Cr::allocator<v8::platform::DefaultWorkerThreadsTaskRunner>, const int &, double (*)(), void> buildtools/third_party/libc++/trunk/include/__memory/shared_ptr.h:936:55 (d8+0x2008d60)
    #9 make_shared<v8::platform::DefaultWorkerThreadsTaskRunner, const int &, double (*)(), void> buildtools/third_party/libc++/trunk/include/__memory/shared_ptr.h:945:12 (d8+0x2008d60)
    #10 EnsureBackgroundTaskRunnerInitialized src/libplatform/default-platform.cc:132:7 (d8+0x2008d60)
    #11 v8::platform::DefaultPlatform::DefaultPlatform(int, v8::platform::IdleTaskSupport, std::Cr::unique_ptr<v8::TracingController, std::Cr::default_delete<v8::TracingController>>) src/libplatform/default-platform.cc:108:5 (d8+0x2008d60)
    #12 make_unique<v8::platform::DefaultPlatform, int &, v8::platform::IdleTaskSupport &, std::Cr::unique_ptr<v8::TracingController, std::Cr::default_delete<v8::TracingController> > > buildtools/third_party/libc++/trunk/include/__memory/unique_ptr.h:686:30 (d8+0x20083d2) (BuildId: 6011f09c007429d6)
    #13 v8::platform::NewDefaultPlatform(int, v8::platform::IdleTaskSupport, v8::platform::InProcessStackDumping, std::Cr::unique_ptr<v8::TracingController, std::Cr::default_delete<v8::TracingController>>) src/libplatform/default-platform.cc:53:19 (d8+0x20083d2)
    #14 v8::Shell::Main(int, char**) src/d8/d8.cc:5805:16 (d8+0x5dea79) (BuildId: 6011f09c007429d6)
    #15 main src/d8/d8.cc:6110:43 (d8+0x5dfe80) (BuildId: 6011f09c007429d6)

SUMMARY: ThreadSanitizer: data race buildtools/third_party/libc++/trunk/include/atomic:948:12 in __cxx_atomic_load<int>
==================
ThreadSanitizer: reported 1 warnings