report: add support for Workers

Include a report for each sub-Worker of the current Node.js instance.

This adds a feature that is necessary for eventually making the report
feature stable, as was discussed during the last collaborator summit.

Refs: openjs-foundation/summit#240

PR-URL: nodejs#31386
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

doc/api/report.md

@@ -297,6 +297,7 @@ is provided below for reference.
       "address": "0x000055fc7b2cb180"
     }
   ],
+  "workers": [],
   "environmentVariables": {
     "REMOTEHOST": "REMOVED",
     "MANPATH": "/opt/rh/devtoolset-3/root/usr/share/man:",
@@ -578,4 +579,24 @@ NODE_OPTIONS="--experimental-report --report-uncaught-exception \
 Specific API documentation can be found under
 [`process API documentation`][] section.
 
+## Interaction with Workers
+<!-- YAML
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/31386
+    description: Workers are now included in the report.
+-->
+
+[`Worker`][] threads can create reports in the same way that the main thread
+does.
+
+Reports will include information on any Workers that are children of the current
+thread as part of the `workers` section, with each Worker generating a report
+in the standard report format.
+
+The thread which is generating the report will wait for the reports from Worker
+threads to finish. However, the latency for this will usually be low, as both
+running JavaScript and the event loop are interrupted to generate the report.
+
 [`process API documentation`]: process.html
+[`Worker`]: worker_threads.html

src/env-inl.h

@@ -893,6 +893,11 @@ inline void Environment::remove_sub_worker_context(worker::Worker* context) {
   sub_worker_contexts_.erase(context);
 }
 
+template <typename Fn>
+inline void Environment::ForEachWorker(Fn&& iterator) {
+  for (worker::Worker* w : sub_worker_contexts_) iterator(w);
+}
+
 inline void Environment::add_refs(int64_t diff) {
   task_queues_async_refs_ += diff;
   CHECK_GE(task_queues_async_refs_, 0);

src/env.h

@@ -1057,6 +1057,8 @@ class Environment : public MemoryRetainer {
   inline void add_sub_worker_context(worker::Worker* context);
   inline void remove_sub_worker_context(worker::Worker* context);
   void stop_sub_worker_contexts();
+  template <typename Fn>
+  inline void ForEachWorker(Fn&& iterator);
   inline bool is_stopping() const;
   inline void set_stopping(bool value);
   inline std::list<node_module>* extra_linked_bindings();

src/node_report.cc

@@ -4,6 +4,8 @@
 #include "diagnosticfilename-inl.h"
 #include "node_internals.h"
 #include "node_metadata.h"
+#include "node_mutex.h"
+#include "node_worker.h"
 #include "util.h"
 
 #ifdef _WIN32
@@ -19,18 +21,20 @@
 #include <cwctype>
 #include <fstream>
 
-constexpr int NODE_REPORT_VERSION = 1;
+constexpr int NODE_REPORT_VERSION = 2;
 constexpr int NANOS_PER_SEC = 1000 * 1000 * 1000;
 constexpr double SEC_PER_MICROS = 1e-6;
 
 namespace report {
 using node::arraysize;
+using node::ConditionVariable;
 using node::DiagnosticFilename;
 using node::Environment;
 using node::Mutex;
 using node::NativeSymbolDebuggingContext;
 using node::PerIsolateOptions;
 using node::TIME_TYPE;
+using node::worker::Worker;
 using v8::HeapSpaceStatistics;
 using v8::HeapStatistics;
 using v8::Isolate;
@@ -210,6 +214,10 @@ static void WriteNodeReport(Isolate* isolate,
 
   // Report native process ID
   writer.json_keyvalue("processId", pid);
+  if (env != nullptr)
+    writer.json_keyvalue("threadId", env->thread_id());
+  else
+    writer.json_keyvalue("threadId", JSONWriter::Null{});
 
   {
     // Report the process cwd.
@@ -259,6 +267,39 @@ static void WriteNodeReport(Isolate* isolate,
 
   writer.json_arrayend();
 
+  writer.json_arraystart("workers");
+  if (env != nullptr) {
+    Mutex workers_mutex;
+    ConditionVariable notify;
+    std::vector<std::string> worker_infos;
+    size_t expected_results = 0;
+
+    env->ForEachWorker([&](Worker* w) {
+      expected_results += w->RequestInterrupt([&](Environment* env) {
+        std::ostringstream os;
+
+        GetNodeReport(env->isolate(),
+                      env,
+                      "Worker thread subreport",
+                      trigger,
+                      Local<String>(),
+                      os);
+
+        Mutex::ScopedLock lock(workers_mutex);
+        worker_infos.emplace_back(os.str());
+        notify.Signal(lock);
+      });
+    });
+
+    Mutex::ScopedLock lock(workers_mutex);
+    worker_infos.reserve(expected_results);
+    while (worker_infos.size() < expected_results)
+      notify.Wait(lock);
+    for (const std::string& worker_info : worker_infos)
+      writer.json_element(JSONWriter::ForeignJSON { worker_info });
+  }
+  writer.json_arrayend();
+
   // Report operating system information
   PrintSystemInformation(&writer);
 

src/node_report.h

@@ -44,6 +44,7 @@ void GetNodeReport(v8::Isolate* isolate,
 // Function declarations - utility functions in src/node_report_utils.cc
 void WalkHandle(uv_handle_t* h, void* arg);
 std::string EscapeJsonChars(const std::string& str);
+std::string Reindent(const std::string& str, int indentation);
 
 template <typename T>
 std::string ValueToHexString(T value) {
@@ -146,6 +147,10 @@ class JSONWriter {
 
   struct Null {};  // Usable as a JSON value.
 
+  struct ForeignJSON {
+    std::string as_string;
+  };
+
  private:
   template <typename T,
             typename test_for_number = typename std::
@@ -161,6 +166,10 @@ class JSONWriter {
   inline void write_value(const char* str) { write_string(str); }
   inline void write_value(const std::string& str) { write_string(str); }
 
+  inline void write_value(const ForeignJSON& json) {
+    out_ << Reindent(json.as_string, indent_);
+  }
+
   inline void write_string(const std::string& str) {
     out_ << '"' << EscapeJsonChars(str) << '"';
   }

src/node_report_utils.cc

@@ -263,4 +263,28 @@ std::string EscapeJsonChars(const std::string& str) {
   return ret;
 }
 
+std::string Reindent(const std::string& str, int indent_depth) {
+  std::string indent;
+  for (int i = 0; i < indent_depth; i++) indent += ' ';
+
+  std::string out;
+  std::string::size_type pos = 0;
+  do {
+    std::string::size_type prev_pos = pos;
+    pos = str.find('\n', pos);
+
+    out.append(indent);
+
+    if (pos == std::string::npos) {
+      out.append(str, prev_pos, std::string::npos);
+      break;
+    } else {
+      pos++;
+      out.append(str, prev_pos, pos - prev_pos);
+    }
+  } while (true);
+
+  return out;
+}
+
 }  // namespace report

test/common/report.js

@@ -53,7 +53,7 @@ function _validateContent(report) {
   // Verify that all sections are present as own properties of the report.
   const sections = ['header', 'javascriptStack', 'nativeStack',
                     'javascriptHeap', 'libuv', 'environmentVariables',
-                    'sharedObjects', 'resourceUsage'];
+                    'sharedObjects', 'resourceUsage', 'workers'];
   if (!isWindows)
     sections.push('userLimits');
 
@@ -74,16 +74,17 @@ function _validateContent(report) {
                         'componentVersions', 'release', 'osName', 'osRelease',
                         'osVersion', 'osMachine', 'cpus', 'host',
                         'glibcVersionRuntime', 'glibcVersionCompiler', 'cwd',
-                        'reportVersion', 'networkInterfaces'];
+                        'reportVersion', 'networkInterfaces', 'threadId'];
   checkForUnknownFields(header, headerFields);
-  assert.strictEqual(header.reportVersion, 1);  // Increment as needed.
+  assert.strictEqual(header.reportVersion, 2);  // Increment as needed.
   assert.strictEqual(typeof header.event, 'string');
   assert.strictEqual(typeof header.trigger, 'string');
   assert(typeof header.filename === 'string' || header.filename === null);
   assert.notStrictEqual(new Date(header.dumpEventTime).toString(),
                         'Invalid Date');
   assert(String(+header.dumpEventTimeStamp), header.dumpEventTimeStamp);
   assert(Number.isSafeInteger(header.processId));
+  assert(Number.isSafeInteger(header.threadId) || header.threadId === null);
   assert.strictEqual(typeof header.cwd, 'string');
   assert(Array.isArray(header.commandLine));
   header.commandLine.forEach((arg) => {
@@ -253,6 +254,10 @@ function _validateContent(report) {
   report.sharedObjects.forEach((sharedObject) => {
     assert.strictEqual(typeof sharedObject, 'string');
   });
+
+  // Verify the format of the workers section.
+  assert(Array.isArray(report.workers));
+  report.workers.forEach(_validateContent);
 }
 
 function checkForUnknownFields(actual, expected) {

test/report/test-report-worker.js

@@ -0,0 +1,50 @@
+// Flags: --experimental-report
+'use strict';
+const common = require('../common');
+common.skipIfReportDisabled();
+const assert = require('assert');
+const { Worker } = require('worker_threads');
+const { once } = require('events');
+const helper = require('../common/report');
+
+async function basic() {
+  // Test that the report includes basic information about Worker threads.
+
+  const w = new Worker(`
+    const { parentPort } = require('worker_threads');
+    parentPort.once('message', () => {
+      /* Wait for message to stop the Worker */
+    });
+  `, { eval: true });
+
+  await once(w, 'online');
+
+  const report = process.report.getReport();
+  helper.validateContent(report);
+  assert.strictEqual(report.workers.length, 1);
+  helper.validateContent(report.workers[0]);
+
+  w.postMessage({});
+
+  await once(w, 'exit');
+}
+
+async function interruptingJS() {
+  // Test that the report also works when Worker threads are busy in JS land.
+
+  const w = new Worker('while (true);', { eval: true });
+
+  await once(w, 'online');
+
+  const report = process.report.getReport();
+  helper.validateContent(report);
+  assert.strictEqual(report.workers.length, 1);
+  helper.validateContent(report.workers[0]);
+
+  await w.terminate();
+}
+
+(async function() {
+  await basic();
+  await interruptingJS();
+})().then(common.mustCall());