workers,trace_events: set thread name for workers

Set the thread name for workers in trace events. Also,
use uint64_t for thread_id_ because there's really no
reason for those to be doubles

src/env-inl.h

@@ -598,11 +598,11 @@ inline bool Environment::is_main_thread() const {
   return thread_id_ == 0;
 }
 
-inline double Environment::thread_id() const {
+inline uint64_t Environment::thread_id() const {
   return thread_id_;
 }
 
-inline void Environment::set_thread_id(double id) {
+inline void Environment::set_thread_id(uint64_t id) {
   thread_id_ = id;
 }
 

src/env.h

@@ -726,8 +726,8 @@ class Environment {
   bool is_stopping_worker() const;
 
   inline bool is_main_thread() const;
-  inline double thread_id() const;
-  inline void set_thread_id(double id);
+  inline uint64_t thread_id() const;
+  inline void set_thread_id(uint64_t id);
   inline worker::Worker* worker_context() const;
   inline void set_worker_context(worker::Worker* context);
   inline void add_sub_worker_context(worker::Worker* context);
@@ -881,7 +881,7 @@ class Environment {
   std::unordered_map<std::string, uint64_t> performance_marks_;
 
   bool can_call_into_js_ = true;
-  double thread_id_ = 0;
+  uint64_t thread_id_ = 0;
   std::unordered_set<worker::Worker*> sub_worker_contexts_;
 
 

src/node_worker.cc

@@ -9,6 +9,8 @@
 #include "async_wrap.h"
 #include "async_wrap-inl.h"
 
+#include <string>
+
 using v8::ArrayBuffer;
 using v8::Context;
 using v8::Function;
@@ -30,7 +32,7 @@ namespace worker {
 
 namespace {
 
-double next_thread_id = 1;
+uint64_t next_thread_id = 1;
 Mutex next_thread_id_mutex;
 
 }  // anonymous namespace
@@ -44,7 +46,8 @@ Worker::Worker(Environment* env, Local<Object> wrap)
   }
   wrap->Set(env->context(),
             env->thread_id_string(),
-            Number::New(env->isolate(), thread_id_)).FromJust();
+            Number::New(env->isolate(),
+                        static_cast<double>(thread_id_))).FromJust();
 
   // Set up everything that needs to be set up in the parent environment.
   parent_port_ = MessagePort::New(env, env->context());
@@ -112,6 +115,11 @@ bool Worker::is_stopped() const {
 }
 
 void Worker::Run() {
+  std::string name = "WorkerThread ";
+  name += std::to_string(thread_id_);
+  TRACE_EVENT_METADATA1(
+      "__metadata", "thread_name", "name",
+      TRACE_STR_COPY(name.c_str()));
   MultiIsolatePlatform* platform = isolate_data_->platform();
   CHECK_NE(platform, nullptr);
 
@@ -418,7 +426,8 @@ void InitWorker(Local<Object> target,
   auto thread_id_string = FIXED_ONE_BYTE_STRING(env->isolate(), "threadId");
   target->Set(env->context(),
               thread_id_string,
-              Number::New(env->isolate(), env->thread_id())).FromJust();
+              Number::New(env->isolate(),
+                          static_cast<double>(env->thread_id()))).FromJust();
 }
 
 }  // anonymous namespace

src/node_worker.h

@@ -62,7 +62,7 @@ class Worker : public AsyncWrap {
 
   bool thread_joined_ = true;
   int exit_code_ = 0;
-  double thread_id_ = -1;
+  uint64_t thread_id_ = -1;
 
   std::unique_ptr<MessagePortData> child_port_data_;
 

test/parallel/test-trace-events-worker-metadata.js

@@ -0,0 +1,33 @@
+// Flags: --experimental-worker
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const cp = require('child_process');
+const fs = require('fs');
+const { isMainThread } = require('worker_threads');
+
+if (isMainThread) {
+  const CODE = 'const { Worker } = require(\'worker_threads\'); ' +
+               `new Worker('${__filename.replace(/\\/g,'/')}')`;
+  const FILE_NAME = 'node_trace.1.log';
+  const tmpdir = require('../common/tmpdir');
+  tmpdir.refresh();
+  process.chdir(tmpdir.path);
+
+  const proc = cp.spawn(process.execPath,
+                        [ '--experimental-worker',
+                          '--trace-event-categories', 'node',
+                          '-e', CODE ]);
+  proc.once('exit', common.mustCall(() => {
+    assert(common.fileExists(FILE_NAME));
+    fs.readFile(FILE_NAME, common.mustCall((err, data) => {
+      const traces = JSON.parse(data.toString()).traceEvents;
+      assert(traces.length > 0);
+      assert(traces.some((trace) =>
+        trace.cat === '__metadata' && trace.name === 'thread_name' &&
+          trace.args.name === 'WorkerThread 1'));
+    }));
+  }));
+} else {
+  // Do nothing here.
+}