[v10.x backport] backport 23233, 22938

src/node.cc

@@ -279,15 +279,18 @@ static struct {
     controller->AddTraceStateObserver(new NodeTraceStateObserver(controller));
     tracing::TraceEventHelper::SetTracingController(controller);
     StartTracingAgent();
+    // Tracing must be initialized before platform threads are created.
     platform_ = new NodePlatform(thread_pool_size, controller);
     V8::InitializePlatform(platform_);
   }
 
   void Dispose() {
-    tracing_agent_.reset(nullptr);
     platform_->Shutdown();
     delete platform_;
     platform_ = nullptr;
+    // Destroy tracing after the platform (and platform threads) have been
+    // stopped.
+    tracing_agent_.reset(nullptr);
   }
 
   void DrainVMTasks(Isolate* isolate) {

src/node_platform.cc

@@ -16,10 +16,28 @@ using v8::Platform;
 using v8::Task;
 using v8::TracingController;
 
+struct PlatformWorkerData {
+  TaskQueue<Task>* task_queue;
+  Mutex* platform_workers_mutex;
+  ConditionVariable* platform_workers_ready;
+  int* pending_platform_workers;
+  int id;
+};
+
 static void BackgroundRunner(void* data) {
+  std::unique_ptr<PlatformWorkerData>
+      worker_data(static_cast<PlatformWorkerData*>(data));
   TRACE_EVENT_METADATA1("__metadata", "thread_name", "name",
                         "BackgroundTaskRunner");
-  TaskQueue<Task> *background_tasks = static_cast<TaskQueue<Task> *>(data);
+
+  // Notify the main thread that the platform worker is ready.
+  {
+    Mutex::ScopedLock lock(*worker_data->platform_workers_mutex);
+    (*worker_data->pending_platform_workers)--;
+    worker_data->platform_workers_ready->Signal(lock);
+  }
+
+  TaskQueue<Task>* background_tasks = worker_data->task_queue;
   while (std::unique_ptr<Task> task = background_tasks->BlockingPop()) {
     task->Run();
     background_tasks->NotifyOfCompletion();
@@ -144,15 +162,29 @@ class BackgroundTaskRunner::DelayedTaskScheduler {
 };
 
 BackgroundTaskRunner::BackgroundTaskRunner(int thread_pool_size) {
+  Mutex::ScopedLock lock(platform_workers_mutex_);
+  pending_platform_workers_ = thread_pool_size;
+
   delayed_task_scheduler_.reset(
       new DelayedTaskScheduler(&background_tasks_));
   threads_.push_back(delayed_task_scheduler_->Start());
+
   for (int i = 0; i < thread_pool_size; i++) {
+    PlatformWorkerData* worker_data = new PlatformWorkerData{
+      &background_tasks_, &platform_workers_mutex_,
+      &platform_workers_ready_, &pending_platform_workers_, i
+    };
     std::unique_ptr<uv_thread_t> t { new uv_thread_t() };
-    if (uv_thread_create(t.get(), BackgroundRunner, &background_tasks_) != 0)
+    if (uv_thread_create(t.get(), BackgroundRunner, worker_data) != 0)
       break;
     threads_.push_back(std::move(t));
   }
+
+  // Wait for platform workers to initialize before continuing with the
+  // bootstrap.
+  while (pending_platform_workers_ > 0) {
+    platform_workers_ready_.Wait(lock);
+  }
 }
 
 void BackgroundTaskRunner::PostTask(std::unique_ptr<Task> task) {
@@ -248,10 +280,9 @@ int PerIsolatePlatformData::unref() {
 NodePlatform::NodePlatform(int thread_pool_size,
                            TracingController* tracing_controller) {
   if (tracing_controller) {
-    tracing_controller_.reset(tracing_controller);
+    tracing_controller_ = tracing_controller;
   } else {
-    TracingController* controller = new TracingController();
-    tracing_controller_.reset(controller);
+    tracing_controller_ = new TracingController();
   }
   background_task_runner_ =
       std::make_shared<BackgroundTaskRunner>(thread_pool_size);
@@ -425,7 +456,7 @@ double NodePlatform::CurrentClockTimeMillis() {
 }
 
 TracingController* NodePlatform::GetTracingController() {
-  return tracing_controller_.get();
+  return tracing_controller_;
 }
 
 template <class T>

src/node_platform.h

@@ -110,13 +110,18 @@ class BackgroundTaskRunner : public v8::TaskRunner {
   void Shutdown();
 
   size_t NumberOfAvailableBackgroundThreads() const;
+
  private:
   TaskQueue<v8::Task> background_tasks_;
 
   class DelayedTaskScheduler;
   std::unique_ptr<DelayedTaskScheduler> delayed_task_scheduler_;
 
   std::vector<std::unique_ptr<uv_thread_t>> threads_;
+
+  Mutex platform_workers_mutex_;
+  ConditionVariable platform_workers_ready_;
+  int pending_platform_workers_;
 };
 
 class NodePlatform : public MultiIsolatePlatform {
@@ -156,7 +161,8 @@ class NodePlatform : public MultiIsolatePlatform {
   std::unordered_map<v8::Isolate*,
                      std::shared_ptr<PerIsolatePlatformData>> per_isolate_;
 
-  std::unique_ptr<v8::TracingController> tracing_controller_;
+
+  v8::TracingController* tracing_controller_;
   std::shared_ptr<BackgroundTaskRunner> background_task_runner_;
 };
 

src/tracing/agent.cc

@@ -48,8 +48,7 @@ using v8::platform::tracing::TraceConfig;
 using v8::platform::tracing::TraceWriter;
 using std::string;
 
-Agent::Agent() {
-  tracing_controller_ = new TracingController();
+Agent::Agent() : tracing_controller_(new TracingController()) {
   tracing_controller_->Initialize(nullptr);
 
   CHECK_EQ(uv_loop_init(&tracing_loop_), 0);
@@ -117,7 +116,7 @@ AgentWriterHandle Agent::AddClient(
     use_categories = &categories_with_default;
   }
 
-  ScopedSuspendTracing suspend(tracing_controller_, this);
+  ScopedSuspendTracing suspend(tracing_controller_.get(), this);
   int id = next_writer_id_++;
   AsyncTraceWriter* raw = writer.get();
   writers_[id] = std::move(writer);
@@ -157,7 +156,7 @@ void Agent::Disconnect(int client) {
     Mutex::ScopedLock lock(initialize_writer_mutex_);
     to_be_initialized_.erase(writers_[client].get());
   }
-  ScopedSuspendTracing suspend(tracing_controller_, this);
+  ScopedSuspendTracing suspend(tracing_controller_.get(), this);
   writers_.erase(client);
   categories_.erase(client);
 }
@@ -166,13 +165,13 @@ void Agent::Enable(int id, const std::set<std::string>& categories) {
   if (categories.empty())
     return;
 
-  ScopedSuspendTracing suspend(tracing_controller_, this,
+  ScopedSuspendTracing suspend(tracing_controller_.get(), this,
                                id != kDefaultHandleId);
   categories_[id].insert(categories.begin(), categories.end());
 }
 
 void Agent::Disable(int id, const std::set<std::string>& categories) {
-  ScopedSuspendTracing suspend(tracing_controller_, this,
+  ScopedSuspendTracing suspend(tracing_controller_.get(), this,
                                id != kDefaultHandleId);
   std::multiset<std::string>& writer_categories = categories_[id];
   for (const std::string& category : categories) {

src/tracing/agent.h

@@ -68,7 +68,9 @@ class Agent {
   Agent();
   ~Agent();
 
-  TracingController* GetTracingController() { return tracing_controller_; }
+  TracingController* GetTracingController() {
+    return tracing_controller_.get();
+  }
 
   enum UseDefaultCategoryMode {
     kUseDefaultCategories,
@@ -119,7 +121,7 @@ class Agent {
   // These maps store the original arguments to AddClient(), by id.
   std::unordered_map<int, std::multiset<std::string>> categories_;
   std::unordered_map<int, std::unique_ptr<AsyncTraceWriter>> writers_;
-  TracingController* tracing_controller_ = nullptr;
+  std::unique_ptr<TracingController> tracing_controller_;
 
   // Variables related to initializing per-event-loop properties of individual
   // writers, such as libuv handles.