Reland "[heap] Introduce LocalIsolate for main thread"

This is a reland of e95e1b6234

After landing https://crrev.com/c/2546682, this CL can be relanded
without changes.

Original change's description:
> [heap] Introduce LocalIsolate for main thread
>
> Add a LocalIsolate for the main thread to Isolate. This LocalIsolate is
> kept alive during the whole lifetime of the Isolate. The main thread
> LocalIsolate starts in the Running state in contrast to the background
> thread LocalIsolates (those start in Parked).
>
> Code paths in Turbofan that used to create a LocalIsolate on the main
> thread can now simply use the main thread LocalIsolate.
>
> LocalIsolate for the main thread will help in reducing differences
> between the main and background threads. The goal is that the main
> thread behaves more like a background thread.
>
> The main thread LocalIsolate should also make it simpler to share code
> between main thread and background threads by using LocalIsolate for
> both.
>
> Bug: v8:10315
> Change-Id: I7fd61d305a6fd7079e2319d75c291c1021e70018
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2509593
> Reviewed-by: Simon Zünd <szuend@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#71226}

Bug: v8:10315
Change-Id: I418b1217aeac4f3c44a0aa514dea9864f8a58656
TBR: szuend@chromium.org, yangguo@chromium.org, ulan@chromium.org, leszeks@chromium.org, neis@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2543399
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71274}

BUILD.gn

@@ -2717,6 +2717,7 @@ v8_source_set("v8_base_without_compiler") {
     "src/heap/paged-spaces.cc",
     "src/heap/paged-spaces.h",
     "src/heap/parallel-work-item.h",
+    "src/heap/parked-scope.h",
     "src/heap/read-only-heap-inl.h",
     "src/heap/read-only-heap.cc",
     "src/heap/read-only-heap.h",

src/DEPS

@@ -25,6 +25,7 @@ include_rules = [
   # TODO(v8:10496): Don't expose memory chunk outside of heap/.
   "+src/heap/memory-chunk.h",
   "+src/heap/memory-chunk-inl.h",
+  "+src/heap/parked-scope.h",
   "+src/heap/read-only-heap-inl.h",
   "+src/heap/read-only-heap.h",
   "+src/heap/safepoint.h",

src/codegen/compiler.cc

@@ -37,6 +37,7 @@
 #include "src/heap/local-factory-inl.h"
 #include "src/heap/local-heap-inl.h"
 #include "src/heap/local-heap.h"
+#include "src/heap/parked-scope.h"
 #include "src/init/bootstrapper.h"
 #include "src/interpreter/interpreter.h"
 #include "src/logging/log-inl.h"
@@ -968,9 +969,10 @@ bool GetOptimizedCodeNow(OptimizedCompilationJob* job, Isolate* isolate,
   }
 
   {
-    LocalIsolate local_isolate(isolate, ThreadKind::kMain);
+    // Park main thread here to be in the same state as background threads.
+    ParkedScope parked_scope(isolate->main_thread_local_isolate());
     if (job->ExecuteJob(isolate->counters()->runtime_call_stats(),
-                        &local_isolate)) {
+                        isolate->main_thread_local_isolate())) {
       CompilerTracer::TraceAbortedJob(isolate, compilation_info);
       return false;
     }

src/compiler-dispatcher/optimizing-compile-dispatcher.cc

@@ -10,6 +10,7 @@
 #include "src/execution/isolate.h"
 #include "src/execution/local-isolate.h"
 #include "src/heap/local-heap.h"
+#include "src/heap/parked-scope.h"
 #include "src/init/v8.h"
 #include "src/logging/counters.h"
 #include "src/logging/log.h"

src/compiler/js-heap-broker.h

@@ -18,6 +18,7 @@
 #include "src/handles/handles.h"
 #include "src/handles/persistent-handles.h"
 #include "src/heap/local-heap.h"
+#include "src/heap/parked-scope.h"
 #include "src/interpreter/bytecode-array-accessor.h"
 #include "src/objects/code-kind.h"
 #include "src/objects/feedback-vector.h"

src/compiler/pipeline.cc

@@ -3034,8 +3034,8 @@ MaybeHandle<Code> Pipeline::GenerateCodeForTesting(
   }
 
   {
-    LocalIsolate local_isolate(isolate, ThreadKind::kMain);
-    LocalIsolateScope local_isolate_scope(data.broker(), info, &local_isolate);
+    LocalIsolateScope local_isolate_scope(data.broker(), info,
+                                          isolate->main_thread_local_isolate());
     if (data.broker()->is_concurrent_inlining()) {
       if (!pipeline.CreateGraph()) return MaybeHandle<Code>();
     }

src/execution/isolate.cc

@@ -39,6 +39,7 @@
 #include "src/diagnostics/compilation-statistics.h"
 #include "src/execution/frames-inl.h"
 #include "src/execution/isolate-inl.h"
+#include "src/execution/local-isolate.h"
 #include "src/execution/messages.h"
 #include "src/execution/microtask-queue.h"
 #include "src/execution/protectors-inl.h"
@@ -2910,6 +2911,7 @@ void Isolate::Delete(Isolate* isolate) {
   Isolate* saved_isolate = reinterpret_cast<Isolate*>(
       base::Thread::GetThreadLocal(isolate->isolate_key_));
   SetIsolateThreadLocals(isolate, nullptr);
+  isolate->set_thread_id(ThreadId::Current());
 
   isolate->Deinit();
 
@@ -3108,6 +3110,8 @@ void Isolate::Deinit() {
   // This stops cancelable tasks (i.e. concurrent marking tasks)
   cancelable_task_manager()->CancelAndWait();
 
+  main_thread_local_isolate_.reset();
+
   heap_.TearDown();
   FILE* logfile = logger_->TearDownAndGetLogFile();
   if (logfile != nullptr) base::Fclose(logfile);
@@ -3539,6 +3543,10 @@ bool Isolate::Init(SnapshotData* startup_snapshot_data,
   ReadOnlyHeap::SetUp(this, read_only_snapshot_data, can_rehash);
   heap_.SetUpSpaces();
 
+  // Create LocalIsolate/LocalHeap for the main thread and set state to Running.
+  main_thread_local_isolate_.reset(new LocalIsolate(this, ThreadKind::kMain));
+  main_thread_local_heap()->Unpark();
+
   isolate_data_.external_reference_table()->Init(this);
 
   // Setup the wasm engine.
@@ -4755,6 +4763,10 @@ void Isolate::RemoveContextIdCallback(const v8::WeakCallbackInfo<void>& data) {
   isolate->recorder_context_id_map_.erase(context_id);
 }
 
+LocalHeap* Isolate::main_thread_local_heap() {
+  return main_thread_local_isolate()->heap();
+}
+
 // |chunk| is either a Page or an executable LargePage.
 void Isolate::RemoveCodeMemoryChunk(MemoryChunk* chunk) {
   // We only keep track of individual code pages/allocations if we are on arm32,

src/execution/isolate.h

@@ -1625,6 +1625,12 @@ class V8_EXPORT_PRIVATE Isolate final : private HiddenFactory {
   MaybeLocal<v8::Context> GetContextFromRecorderContextId(
       v8::metrics::Recorder::ContextId id);
 
+  LocalIsolate* main_thread_local_isolate() {
+    return main_thread_local_isolate_.get();
+  }
+
+  LocalHeap* main_thread_local_heap();
+
 #ifdef V8_HEAP_SANDBOX
   ExternalPointerTable& external_pointer_table() {
     return isolate_data_.external_pointer_table_;
@@ -1961,6 +1967,8 @@ class V8_EXPORT_PRIVATE Isolate final : private HiddenFactory {
   bool promise_hook_or_debug_is_active_or_async_event_delegate_ = false;
   int async_task_count_ = 0;
 
+  std::unique_ptr<LocalIsolate> main_thread_local_isolate_;
+
   v8::Isolate::AbortOnUncaughtExceptionCallback
       abort_on_uncaught_exception_callback_ = nullptr;
 

src/handles/handles.cc

@@ -7,6 +7,8 @@
 #include "src/api/api.h"
 #include "src/base/logging.h"
 #include "src/codegen/optimized-compilation-info.h"
+#include "src/execution/isolate.h"
+#include "src/execution/thread-id.h"
 #include "src/handles/maybe-handles.h"
 #include "src/objects/objects-inl.h"
 #include "src/roots/roots-inl.h"
@@ -43,8 +45,19 @@ bool HandleBase::IsDereferenceAllowed() const {
   }
   if (isolate->IsBuiltinsTableHandleLocation(location_)) return true;
 
-  LocalHeap* local_heap = LocalHeap::Current();
-  if (FLAG_local_heaps && local_heap) {
+  if (FLAG_local_heaps) {
+    LocalHeap* local_heap = LocalHeap::Current();
+
+    if (local_heap == nullptr) {
+      // We are on the main thread and can thus load the LocalHeap from the
+      // Isolate itself. The DCHECK makes sure that we are not accidentally
+      // dereferencing a handle on a background thread without an active
+      // LocalHeap.
+      DCHECK_EQ(ThreadId::Current(), isolate->thread_id());
+      local_heap = isolate->main_thread_local_heap();
+    }
+
+    // Local heap can't access handles when parked
     if (!local_heap->IsHandleDereferenceAllowed()) {
       StdoutStream{} << "Cannot dereference handle owned by "
                      << "non-running local heap\n";

src/heap/concurrent-allocator-inl.h

@@ -23,8 +23,9 @@ AllocationResult ConcurrentAllocator::AllocateRaw(int object_size,
   // TODO(dinfuehr): Add support for allocation observers
   CHECK(FLAG_concurrent_allocation);
 
-  // Ensure that we are on the right thread
-  DCHECK_EQ(LocalHeap::Current(), local_heap_);
+#ifdef DEBUG
+  local_heap_->VerifyCurrent();
+#endif
 
   if (object_size > kMaxLabObjectSize) {
     return AllocateOutsideLab(object_size, alignment, origin);

src/heap/concurrent-allocator.cc

@@ -12,6 +12,7 @@
 #include "src/heap/local-heap.h"
 #include "src/heap/marking.h"
 #include "src/heap/memory-chunk.h"
+#include "src/heap/parked-scope.h"
 
 namespace v8 {
 namespace internal {

src/heap/local-heap-inl.h

@@ -16,7 +16,7 @@ AllocationResult LocalHeap::AllocateRaw(int size_in_bytes, AllocationType type,
                                         AllocationOrigin origin,
                                         AllocationAlignment alignment) {
 #if DEBUG
-  DCHECK_EQ(LocalHeap::Current(), this);
+  VerifyCurrent();
   DCHECK(AllowHandleAllocation::IsAllowed());
   DCHECK(AllowHeapAllocation::IsAllowed());
   DCHECK_IMPLIES(type == AllocationType::kCode || type == AllocationType::kMap,

src/heap/local-heap.cc

@@ -6,13 +6,16 @@
 
 #include <memory>
 
+#include "src/base/logging.h"
 #include "src/base/platform/mutex.h"
 #include "src/common/globals.h"
+#include "src/execution/isolate.h"
 #include "src/handles/local-handles.h"
 #include "src/heap/heap-inl.h"
 #include "src/heap/heap-write-barrier.h"
 #include "src/heap/local-heap-inl.h"
 #include "src/heap/marking-barrier.h"
+#include "src/heap/parked-scope.h"
 #include "src/heap/safepoint.h"
 
 namespace v8 {
@@ -24,6 +27,17 @@ thread_local LocalHeap* current_local_heap = nullptr;
 
 LocalHeap* LocalHeap::Current() { return current_local_heap; }
 
+#ifdef DEBUG
+void LocalHeap::VerifyCurrent() {
+  LocalHeap* current = LocalHeap::Current();
+
+  if (is_main_thread())
+    DCHECK_NULL(current);
+  else
+    DCHECK_EQ(current, this);
+}
+#endif
+
 LocalHeap::LocalHeap(Heap* heap, ThreadKind kind,
                      std::unique_ptr<PersistentHandles> persistent_handles)
     : heap_(heap),
@@ -38,7 +52,7 @@ LocalHeap::LocalHeap(Heap* heap, ThreadKind kind,
       marking_barrier_(new MarkingBarrier(this)),
       old_space_allocator_(this, heap->old_space()) {
   heap_->safepoint()->AddLocalHeap(this, [this] {
-    if (FLAG_local_heaps) {
+    if (FLAG_local_heaps && !is_main_thread()) {
       WriteBarrier::SetForThread(marking_barrier_.get());
       if (heap_->incremental_marking()->IsMarking()) {
         marking_barrier_->Activate(
@@ -51,7 +65,7 @@ LocalHeap::LocalHeap(Heap* heap, ThreadKind kind,
     persistent_handles_->Attach(this);
   }
   DCHECK_NULL(current_local_heap);
-  current_local_heap = this;
+  if (!is_main_thread()) current_local_heap = this;
 }
 
 LocalHeap::~LocalHeap() {
@@ -61,14 +75,16 @@ LocalHeap::~LocalHeap() {
   heap_->safepoint()->RemoveLocalHeap(this, [this] {
     old_space_allocator_.FreeLinearAllocationArea();
 
-    if (FLAG_local_heaps) {
+    if (FLAG_local_heaps && !is_main_thread()) {
       marking_barrier_->Publish();
       WriteBarrier::ClearForThread(marking_barrier_.get());
     }
   });
 
-  DCHECK_EQ(current_local_heap, this);
-  current_local_heap = nullptr;
+  if (!is_main_thread()) {
+    DCHECK_EQ(current_local_heap, this);
+    current_local_heap = nullptr;
+  }
 }
 
 void LocalHeap::EnsurePersistentHandles() {
@@ -101,13 +117,17 @@ bool LocalHeap::ContainsLocalHandle(Address* location) {
 }
 
 bool LocalHeap::IsHandleDereferenceAllowed() {
-  DCHECK_EQ(LocalHeap::Current(), this);
+#ifdef DEBUG
+  VerifyCurrent();
+#endif
   return state_ == ThreadState::Running;
 }
 #endif
 
 bool LocalHeap::IsParked() {
-  DCHECK_EQ(LocalHeap::Current(), this);
+#ifdef DEBUG
+  VerifyCurrent();
+#endif
   return state_ == ThreadState::Parked;
 }
 

src/heap/local-heap.h

@@ -111,6 +111,10 @@ class V8_EXPORT_PRIVATE LocalHeap {
   // with the current thread.
   static LocalHeap* Current();
 
+#ifdef DEBUG
+  void VerifyCurrent();
+#endif
+
   // Allocate an uninitialized object.
   V8_WARN_UNUSED_RESULT inline AllocationResult AllocateRaw(
       int size_in_bytes, AllocationType allocation,
@@ -185,47 +189,7 @@ class V8_EXPORT_PRIVATE LocalHeap {
   friend class ParkedScope;
   friend class UnparkedScope;
   friend class ConcurrentAllocator;
-};
-
-// Scope that explicitly parks LocalHeap prohibiting access to the heap and the
-// creation of Handles.
-class ParkedScope {
- public:
-  explicit ParkedScope(LocalHeap* local_heap) : local_heap_(local_heap) {
-    local_heap_->Park();
-  }
-
-  ~ParkedScope() { local_heap_->Unpark(); }
-
- private:
-  LocalHeap* const local_heap_;
-};
-
-// Scope that explicitly unparks LocalHeap allowing access to the heap and the
-// creation of Handles.
-class UnparkedScope {
- public:
-  explicit UnparkedScope(LocalHeap* local_heap) : local_heap_(local_heap) {
-    local_heap_->Unpark();
-  }
-
-  ~UnparkedScope() { local_heap_->Park(); }
-
- private:
-  LocalHeap* const local_heap_;
-};
-
-class ParkedMutexGuard {
-  base::Mutex* guard_;
-
- public:
-  explicit ParkedMutexGuard(LocalHeap* local_heap, base::Mutex* guard)
-      : guard_(guard) {
-    ParkedScope scope(local_heap);
-    guard_->Lock();
-  }
-
-  ~ParkedMutexGuard() { guard_->Unlock(); }
+  friend class Isolate;
 };
 
 }  // namespace internal

src/heap/parked-scope.h

@@ -0,0 +1,65 @@
+// Copyright 2020 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.
+
+#ifndef V8_HEAP_PARKED_SCOPE_H_
+#define V8_HEAP_PARKED_SCOPE_H_
+
+#include "src/base/platform/mutex.h"
+#include "src/execution/local-isolate.h"
+#include "src/heap/local-heap.h"
+
+namespace v8 {
+namespace internal {
+
+// Scope that explicitly parks a thread, prohibiting access to the heap and the
+// creation of handles.
+class ParkedScope {
+ public:
+  explicit ParkedScope(LocalIsolate* local_isolate)
+      : ParkedScope(local_isolate->heap()) {}
+  explicit ParkedScope(LocalHeap* local_heap) : local_heap_(local_heap) {
+    local_heap_->Park();
+  }
+
+  ~ParkedScope() { local_heap_->Unpark(); }
+
+ private:
+  LocalHeap* const local_heap_;
+};
+
+// Scope that explicitly unparks a thread, allowing access to the heap and the
+// creation of handles.
+class UnparkedScope {
+ public:
+  explicit UnparkedScope(LocalIsolate* local_isolate)
+      : UnparkedScope(local_isolate->heap()) {}
+  explicit UnparkedScope(LocalHeap* local_heap) : local_heap_(local_heap) {
+    local_heap_->Unpark();
+  }
+
+  ~UnparkedScope() { local_heap_->Park(); }
+
+ private:
+  LocalHeap* const local_heap_;
+};
+
+class ParkedMutexGuard {
+  base::Mutex* guard_;
+
+ public:
+  explicit ParkedMutexGuard(LocalIsolate* local_isolate, base::Mutex* guard)
+      : ParkedMutexGuard(local_isolate->heap(), guard) {}
+  explicit ParkedMutexGuard(LocalHeap* local_heap, base::Mutex* guard)
+      : guard_(guard) {
+    ParkedScope scope(local_heap);
+    guard_->Lock();
+  }
+
+  ~ParkedMutexGuard() { guard_->Unlock(); }
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_HEAP_PARKED_SCOPE_H_

src/heap/safepoint.cc

@@ -4,6 +4,7 @@
 
 #include "src/heap/safepoint.h"
 
+#include "src/base/logging.h"
 #include "src/handles/local-handles.h"
 #include "src/handles/persistent-handles.h"
 #include "src/heap/gc-tracer.h"
@@ -25,13 +26,13 @@ void GlobalSafepoint::EnterSafepointScope() {
   TRACE_GC(heap_->tracer(), GCTracer::Scope::STOP_THE_WORLD);
 
   local_heaps_mutex_.Lock();
-  local_heap_of_this_thread_ = LocalHeap::Current();
 
   barrier_.Arm();
+  DCHECK_NULL(LocalHeap::Current());
 
   for (LocalHeap* current = local_heaps_head_; current;
        current = current->next_) {
-    if (current == local_heap_of_this_thread_) {
+    if (current->is_main_thread()) {
       continue;
     }
     current->RequestSafepoint();
@@ -39,8 +40,7 @@ void GlobalSafepoint::EnterSafepointScope() {
 
   for (LocalHeap* current = local_heaps_head_; current;
        current = current->next_) {
-    if (current == local_heap_of_this_thread_) {
-      DCHECK(current->is_main_thread());
+    if (current->is_main_thread()) {
       continue;
     }
     DCHECK(!current->is_main_thread());
@@ -58,11 +58,11 @@ void GlobalSafepoint::LeaveSafepointScope() {
   DCHECK_GT(active_safepoint_scopes_, 0);
   if (--active_safepoint_scopes_ > 0) return;
 
-  DCHECK_EQ(local_heap_of_this_thread_, LocalHeap::Current());
+  DCHECK_NULL(LocalHeap::Current());
 
   for (LocalHeap* current = local_heaps_head_; current;
        current = current->next_) {
-    if (current == local_heap_of_this_thread_) {
+    if (current->is_main_thread()) {
       continue;
     }
     current->state_mutex_.Unlock();
@@ -70,7 +70,6 @@ void GlobalSafepoint::LeaveSafepointScope() {
 
   barrier_.Disarm();
 
-  local_heap_of_this_thread_ = nullptr;
   local_heaps_mutex_.Unlock();
 }
 

src/heap/safepoint.h

@@ -101,8 +101,6 @@ class GlobalSafepoint {
 
   int active_safepoint_scopes_;
 
-  LocalHeap* local_heap_of_this_thread_;
-
   friend class SafepointScope;
   friend class LocalHeap;
   friend class PersistentHandles;

src/inspector/v8-inspector-session-impl.cc

@@ -145,6 +145,7 @@ V8InspectorSessionImpl::V8InspectorSessionImpl(V8InspectorImpl* inspector,
 }
 
 V8InspectorSessionImpl::~V8InspectorSessionImpl() {
+  v8::Isolate::Scope scope(m_inspector->isolate());
   discardInjectedScripts();
   m_consoleAgent->disable();
   m_profilerAgent->disable();

test/cctest/heap/test-concurrent-allocation.cc

@@ -20,6 +20,7 @@
 #include "src/heap/concurrent-allocator-inl.h"
 #include "src/heap/heap.h"
 #include "src/heap/local-heap-inl.h"
+#include "src/heap/parked-scope.h"
 #include "src/heap/safepoint.h"
 #include "src/objects/heap-number.h"
 #include "src/objects/heap-object.h"
@@ -126,11 +127,7 @@ UNINITIALIZED_TEST(ConcurrentAllocationInOldSpaceFromMainThread) {
   v8::Isolate* isolate = v8::Isolate::New(create_params);
   Isolate* i_isolate = reinterpret_cast<Isolate*>(isolate);
 
-  {
-    LocalHeap local_heap(i_isolate->heap(), ThreadKind::kMain);
-    UnparkedScope unparked_scope(&local_heap);
-    AllocateSomeObjects(&local_heap);
-  }
+  AllocateSomeObjects(i_isolate->main_thread_local_heap());
 
   isolate->Dispose();
 }

test/cctest/heap/test-heap.cc

@@ -47,6 +47,7 @@
 #include "src/heap/mark-compact.h"
 #include "src/heap/memory-chunk.h"
 #include "src/heap/memory-reducer.h"
+#include "src/heap/parked-scope.h"
 #include "src/heap/remembered-set-inl.h"
 #include "src/heap/safepoint.h"
 #include "src/ic/ic.h"
@@ -7118,12 +7119,11 @@ TEST(GarbageCollectionWithLocalHeap) {
   ManualGCScope manual_gc_scope;
   CcTest::InitializeVM();
 
-  Heap* heap = CcTest::i_isolate()->heap();
+  LocalHeap* local_heap = CcTest::i_isolate()->main_thread_local_heap();
 
-  LocalHeap local_heap(heap, ThreadKind::kMain);
-  UnparkedScope unparked_scope(&local_heap);
   CcTest::CollectGarbage(OLD_SPACE);
-  { ParkedScope parked_scope(&local_heap); }
+
+  { ParkedScope parked_scope(local_heap); }
   CcTest::CollectGarbage(OLD_SPACE);
 }
 

test/cctest/test-concurrent-descriptor-array.cc

@@ -10,6 +10,7 @@
 #include "src/heap/heap.h"
 #include "src/heap/local-heap-inl.h"
 #include "src/heap/local-heap.h"
+#include "src/heap/parked-scope.h"
 #include "test/cctest/cctest.h"
 #include "test/cctest/heap/heap-utils.h"
 

test/cctest/test-concurrent-feedback-vector.cc

@@ -12,6 +12,7 @@
 #include "src/handles/persistent-handles.h"
 #include "src/heap/heap.h"
 #include "src/heap/local-heap.h"
+#include "src/heap/parked-scope.h"
 #include "test/cctest/cctest.h"
 #include "test/cctest/heap/heap-utils.h"
 

test/cctest/test-concurrent-prototype.cc

@@ -10,6 +10,7 @@
 #include "src/heap/heap.h"
 #include "src/heap/local-heap-inl.h"
 #include "src/heap/local-heap.h"
+#include "src/heap/parked-scope.h"
 #include "test/cctest/cctest.h"
 #include "test/cctest/heap/heap-utils.h"
 

test/cctest/test-concurrent-script-context-table.cc

@@ -9,6 +9,7 @@
 #include "src/handles/persistent-handles.h"
 #include "src/heap/heap.h"
 #include "src/heap/local-heap.h"
+#include "src/heap/parked-scope.h"
 #include "src/objects/contexts.h"
 #include "test/cctest/cctest.h"
 #include "test/cctest/heap/heap-utils.h"

test/cctest/test-concurrent-string.cc

@@ -10,6 +10,7 @@
 #include "src/heap/heap.h"
 #include "src/heap/local-heap-inl.h"
 #include "src/heap/local-heap.h"
+#include "src/heap/parked-scope.h"
 #include "test/cctest/cctest.h"
 #include "test/cctest/heap/heap-utils.h"
 

test/cctest/test-concurrent-transition-array.cc

@@ -8,6 +8,7 @@
 #include "src/handles/persistent-handles.h"
 #include "src/heap/heap.h"
 #include "src/heap/local-heap.h"
+#include "src/heap/parked-scope.h"
 #include "src/objects/transitions-inl.h"
 #include "test/cctest/cctest.h"
 #include "test/cctest/heap/heap-utils.h"

test/cctest/test-local-handles.cc

@@ -14,6 +14,7 @@
 #include "src/handles/local-handles.h"
 #include "src/heap/heap.h"
 #include "src/heap/local-heap.h"
+#include "src/heap/parked-scope.h"
 #include "src/heap/safepoint.h"
 #include "src/objects/heap-number.h"
 #include "test/cctest/cctest.h"
@@ -102,11 +103,7 @@ TEST(CreateLocalHandlesWithoutLocalHandleScope) {
   CcTest::InitializeVM();
   Isolate* isolate = CcTest::i_isolate();
 
-  {
-    LocalHeap local_heap(isolate->heap(), ThreadKind::kMain);
-    UnparkedScope scope(&local_heap);
-    handle(Smi::FromInt(17), &local_heap);
-  }
+  handle(Smi::FromInt(17), isolate->main_thread_local_heap());
 }
 
 TEST(DereferenceLocalHandle) {
@@ -124,7 +121,8 @@ TEST(DereferenceLocalHandle) {
     ph = phs->NewHandle(number);
   }
   {
-    LocalHeap local_heap(isolate->heap(), ThreadKind::kMain, std::move(phs));
+    LocalHeap local_heap(isolate->heap(), ThreadKind::kBackground,
+                         std::move(phs));
     UnparkedScope unparked_scope(&local_heap);
     LocalHandleScope scope(&local_heap);
     Handle<HeapNumber> local_number = handle(*ph, &local_heap);

test/cctest/test-lockers.cc

@@ -54,13 +54,15 @@ class DeoptimizeCodeThread : public v8::base::Thread {
   void Run() override {
     v8::Locker locker(isolate_);
     isolate_->Enter();
-    v8::HandleScope handle_scope(isolate_);
-    v8::Local<v8::Context> context =
-        v8::Local<v8::Context>::New(isolate_, context_);
-    v8::Context::Scope context_scope(context);
-    // This code triggers deoptimization of some function that will be
-    // used in a different thread.
-    CompileRun(source_);
+    {
+      v8::HandleScope handle_scope(isolate_);
+      v8::Local<v8::Context> context =
+          v8::Local<v8::Context>::New(isolate_, context_);
+      v8::Context::Scope context_scope(context);
+      // This code triggers deoptimization of some function that will be
+      // used in a different thread.
+      CompileRun(source_);
+    }
     isolate_->Exit();
   }
 

test/cctest/test-persistent-handles.cc

@@ -14,6 +14,7 @@
 #include "src/heap/heap.h"
 #include "src/heap/local-heap-inl.h"
 #include "src/heap/local-heap.h"
+#include "src/heap/parked-scope.h"
 #include "src/heap/safepoint.h"
 #include "src/objects/heap-number.h"
 #include "test/cctest/cctest.h"
@@ -129,7 +130,8 @@ TEST(DereferencePersistentHandle) {
     ph = phs->NewHandle(number);
   }
   {
-    LocalHeap local_heap(isolate->heap(), ThreadKind::kMain, std::move(phs));
+    LocalHeap local_heap(isolate->heap(), ThreadKind::kBackground,
+                         std::move(phs));
     UnparkedScope scope(&local_heap);
     CHECK_EQ(42, ph->value());
     DisallowHandleDereference disallow_scope;
@@ -141,7 +143,7 @@ TEST(NewPersistentHandleFailsWhenParked) {
   CcTest::InitializeVM();
   Isolate* isolate = CcTest::i_isolate();
 
-  LocalHeap local_heap(isolate->heap(), ThreadKind::kMain);
+  LocalHeap local_heap(isolate->heap(), ThreadKind::kBackground);
   // Fail here in debug mode: Persistent handles can't be created if local heap
   // is parked
   local_heap.NewPersistentHandle(Smi::FromInt(1));
@@ -151,7 +153,7 @@ TEST(NewPersistentHandleFailsWhenParkedExplicit) {
   CcTest::InitializeVM();
   Isolate* isolate = CcTest::i_isolate();
 
-  LocalHeap local_heap(isolate->heap(), ThreadKind::kMain,
+  LocalHeap local_heap(isolate->heap(), ThreadKind::kBackground,
                        isolate->NewPersistentHandles());
   // Fail here in debug mode: Persistent handles can't be created if local heap
   // is parked

test/unittests/compiler-dispatcher/compiler-dispatcher-unittest.cc

@@ -38,6 +38,7 @@ class CompilerDispatcherTestFlags {
     FLAG_single_threaded = true;
     FlagList::EnforceFlagImplications();
     FLAG_compiler_dispatcher = true;
+    FLAG_finalize_streaming_on_background = false;
   }
 
   static void RestoreFlags() {

test/unittests/heap/local-factory-unittest.cc

@@ -62,8 +62,7 @@ class LocalFactoryTest : public TestWithIsolateAndZone {
                 isolate(), true, construct_language_mode(FLAG_use_strict),
                 REPLMode::kNo),
             &state_),
-        local_isolate_(isolate(), ThreadKind::kMain),
-        unparked_scope_(local_isolate_.heap()) {
+        local_isolate_(isolate()->main_thread_local_isolate()) {
     FLAG_concurrent_allocation = true;
   }
 
@@ -107,15 +106,14 @@ class LocalFactoryTest : public TestWithIsolateAndZone {
 
   Handle<Script> script() { return script_; }
 
-  LocalIsolate* local_isolate() { return &local_isolate_; }
+  LocalIsolate* local_isolate() { return local_isolate_; }
   LocalFactory* local_factory() { return local_isolate()->factory(); }
 
  private:
   SaveFlags save_flags_;
   UnoptimizedCompileState state_;
   ParseInfo parse_info_;
-  LocalIsolate local_isolate_;
-  UnparkedScope unparked_scope_;
+  LocalIsolate* local_isolate_;
   Handle<String> source_string_;
   Handle<Script> script_;
 };

test/unittests/heap/local-heap-unittest.cc

@@ -15,15 +15,7 @@ using LocalHeapTest = TestWithIsolate;
 
 TEST_F(LocalHeapTest, Initialize) {
   Heap* heap = i_isolate()->heap();
-
-  CHECK(!heap->safepoint()->ContainsAnyLocalHeap());
-
-  {
-    LocalHeap lh(heap, ThreadKind::kMain);
-    CHECK(heap->safepoint()->ContainsLocalHeap(&lh));
-  }
-
-  CHECK(!heap->safepoint()->ContainsAnyLocalHeap());
+  CHECK(heap->safepoint()->ContainsAnyLocalHeap());
 }
 
 TEST_F(LocalHeapTest, Current) {
@@ -33,14 +25,14 @@ TEST_F(LocalHeapTest, Current) {
 
   {
     LocalHeap lh(heap, ThreadKind::kMain);
-    CHECK_EQ(&lh, LocalHeap::Current());
+    CHECK_NULL(LocalHeap::Current());
   }
 
   CHECK_NULL(LocalHeap::Current());
 
   {
     LocalHeap lh(heap, ThreadKind::kMain);
-    CHECK_EQ(&lh, LocalHeap::Current());
+    CHECK_NULL(LocalHeap::Current());
   }
 
   CHECK_NULL(LocalHeap::Current());
@@ -73,9 +65,9 @@ TEST_F(LocalHeapTest, CurrentBackground) {
     LocalHeap lh(heap, ThreadKind::kMain);
     auto thread = std::make_unique<BackgroundThread>(heap);
     CHECK(thread->Start());
-    CHECK_EQ(&lh, LocalHeap::Current());
+    CHECK_NULL(LocalHeap::Current());
     thread->Join();
-    CHECK_EQ(&lh, LocalHeap::Current());
+    CHECK_NULL(LocalHeap::Current());
   }
   CHECK_NULL(LocalHeap::Current());
 }

test/unittests/heap/safepoint-unittest.cc

@@ -3,10 +3,12 @@
 // found in the LICENSE file.
 
 #include "src/heap/safepoint.h"
+
 #include "src/base/platform/mutex.h"
 #include "src/base/platform/platform.h"
 #include "src/heap/heap.h"
 #include "src/heap/local-heap.h"
+#include "src/heap/parked-scope.h"
 #include "test/unittests/test-utils.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -144,25 +146,5 @@ TEST_F(SafepointTest, StopRunningThreads) {
   CHECK_EQ(safepoint_count, kRuns * kSafepoints);
 }
 
-TEST_F(SafepointTest, SkipLocalHeapOfThisThread) {
-  EnsureFlagLocalHeapsEnabled();
-  Heap* heap = i_isolate()->heap();
-  LocalHeap local_heap(heap, ThreadKind::kMain);
-  UnparkedScope unparked_scope(&local_heap);
-  {
-    SafepointScope scope(heap);
-    local_heap.Safepoint();
-  }
-  {
-    ParkedScope parked_scope(&local_heap);
-    SafepointScope scope(heap);
-    local_heap.Safepoint();
-  }
-  {
-    SafepointScope scope(heap);
-    local_heap.Safepoint();
-  }
-}
-
 }  // namespace internal
 }  // namespace v8