Run Dart VM tasks on the engine's ConcurrentMessageLoop instead the VM's separate thread pool. (#29819)

Bug: dart-lang/sdk#44228

Author: rmacnak-google

runtime/dart_isolate_unittests.cc

@@ -335,7 +335,54 @@ TEST_F(DartSecondaryIsolateTest, CanLaunchSecondaryIsolates) {
  // root isolate will be auto-shutdown
 }
 
-TEST_F(DartIsolateTest, CanReceiveArguments) {
+static thread_local bool is_engine_worker = false;
+
+TEST_F(DartSecondaryIsolateTest, VMTasksRunOnEngineThreads) {
+ AddNativeCallback("NotifyNative",
+ CREATE_NATIVE_ENTRY(([this](Dart_NativeArguments args) {
+ LatchCountDown();
+ })));
+ AddNativeCallback("PassMessage",
+ CREATE_NATIVE_ENTRY(([this](Dart_NativeArguments args) {
+ // Child isolate is running on concurrent message loop
+ // worker.
+ ASSERT_TRUE(is_engine_worker);
+ LatchCountDown();
+ })));
+ auto settings = CreateSettingsForFixture();
+ settings.root_isolate_shutdown_callback = [this]() {
+ RootIsolateShutdownSignal();
+ };
+ settings.isolate_shutdown_callback = [this]() { ChildShutdownSignal(); };
+ auto vm_ref = DartVMRef::Create(settings);
+
+ auto loop = vm_ref->GetConcurrentMessageLoop();
+ fml::CountDownLatch latch(loop->GetWorkerCount());
+ vm_ref->GetConcurrentMessageLoop()->PostTaskToAllWorkers([&] {
+ is_engine_worker = true;
+ latch.CountDown();
+ });
+ latch.Wait();
+
+ auto thread = CreateNewThread();
+ TaskRunners task_runners(GetCurrentTestName(), //
+ thread, //
+ thread, //
+ thread, //
+ thread //
+ );
+ auto isolate = RunDartCodeInIsolate(vm_ref, settings, task_runners,
+ "testCanLaunchSecondaryIsolate", {},
+ GetDefaultKernelFilePath());
+ ASSERT_TRUE(isolate);
+ ASSERT_EQ(isolate->get()->GetPhase(), DartIsolate::Phase::Running);
+ ChildShutdownWait(); // wait for child isolate to shutdown first
+ ASSERT_FALSE(RootIsolateIsSignaled());
+ LatchWait(); // wait for last NotifyNative called by main isolate
+ // root isolate will be auto-shutdown
+}
+
+TEST_F(DartIsolateTest, CanRecieveArguments) {
  AddNativeCallback("NotifyNative",
  CREATE_NATIVE_ENTRY(([this](Dart_NativeArguments args) {
  ASSERT_TRUE(tonic::DartConverter<bool>::FromDart(

runtime/dart_vm.cc

@@ -170,6 +170,14 @@ Dart_Handle GetVMServiceAssetsArchiveCallback() {
 #endif
 }
 
+void PostTaskCallback(void* post_task_data,
+ Dart_Task task,
+ Dart_TaskData task_data) {
+ auto* dart_vm = reinterpret_cast<DartVM*>(post_task_data);
+ dart_vm->GetConcurrentWorkerTaskRunner()->PostTask(
+ [task] { Dart_RunTask(task); });
+}
+
 static const char kStdoutStreamId[] = "Stdout";
 static const char kStderrStreamId[] = "Stderr";
 
@@ -442,6 +450,8 @@ DartVM::DartVM(std::shared_ptr<const DartVMData> vm_data,
  params.thread_exit = ThreadExitCallback;
  params.get_service_assets = GetVMServiceAssetsArchiveCallback;
  params.entropy_source = dart::bin::GetEntropy;
+ params.post_task = PostTaskCallback;
+ params.post_task_data = this;
  DartVMInitializer::Initialize(&params);
  // Send the earliest available timestamp in the application lifecycle to
  // timeline. The difference between this timestamp and the time we render
@@ -476,6 +486,10 @@ DartVM::DartVM(std::shared_ptr<const DartVMData> vm_data,
  Dart_SetDartLibrarySourcesKernel(dart_library_sources->GetMapping(),
  dart_library_sources->GetSize());
  }
+
+ // Update thread names now that the Dart VM is initialized.
+ concurrent_message_loop_->PostTaskToAllWorkers(
+ [] { Dart_SetThreadName("FlutterConcurrentMessageLoopWorker"); });
 }
 
 DartVM::~DartVM() {