inspector: implement --heap-prof

In addition implements --heap-prof-name, --heap-prof-dir and
--heap-prof-interval.
These flags are similar to --cpu-prof flags but they are meant
for the V8 sampling heap profiler instead of the CPU profiler.

PR-URL: #27596
Fixes: #27421
Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

doc/api/cli.md

@@ -245,6 +245,57 @@ new X();
 added: v12.0.0
 -->
 
+### `--heap-prof`
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+Starts the V8 heap profiler on start up, and writes the heap profile to disk
+before exit.
+
+If `--heap-prof-dir` is not specified, the generated profile will be placed
+in the current working directory.
+
+If `--heap-prof-name` is not specified, the generated profile will be
+named `Heap.${yyyymmdd}.${hhmmss}.${pid}.${tid}.${seq}.heapprofile`.
+
+```console
+$ node --heap-prof index.js
+$ ls *.heapprofile
+Heap.20190409.202950.15293.0.001.heapprofile
+```
+
+### `--heap-prof-dir`
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+Specify the directory where the heap profiles generated by `--heap-prof` will
+be placed.
+
+### `--heap-prof-interval`
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+Specify the average sampling interval in bytes for the heap profiles generated
+by `--heap-prof`. The default is 512 * 1024 bytes.
+
+### `--heap-prof-name`
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+Specify the file name of the heap profile generated by `--heap-prof`.
+
 Generates a heap snapshot each time the process receives the specified signal.
 `signal` must be a valid signal name. Disabled by default.
 

doc/node.1

@@ -139,6 +139,28 @@ Enable experimental frozen intrinsics support.
 .It Fl -heapsnapshot-signal Ns = Ns Ar signal
 Generate heap snapshot on specified signal.
 .
+.It Fl -heap-prof
+Start the V8 heap profiler on start up, and write the heap profile to disk
+before exit. If
+.Fl -heap-prof-dir
+is not specified, the profile will be written to the current working directory
+with a generated file name.
+.
+.It Fl -heap-prof-dir
+The directory where the heap profiles generated by
+.Fl -heap-prof
+will be placed.
+.
+.It Fl -heap-prof-interval
+The average sampling interval in bytes for the heap profiles generated by
+.Fl -heap-prof .
+The default is
+.Sy 512 * 1024 .
+.
+.It Fl -heap-prof-name
+File name of the V8 heap profile generated with
+.Fl -heap-prof
+.
 .It Fl -http-parser Ns = Ns Ar library
 Chooses an HTTP parser library. Available values are
 .Sy llhttp

src/env-inl.h

@@ -689,6 +689,41 @@ inline const std::string& Environment::cpu_prof_dir() const {
   return cpu_prof_dir_;
 }
 
+inline void Environment::set_heap_profiler_connection(
+    std::unique_ptr<profiler::V8HeapProfilerConnection> connection) {
+  CHECK_NULL(heap_profiler_connection_);
+  std::swap(heap_profiler_connection_, connection);
+}
+
+inline profiler::V8HeapProfilerConnection*
+Environment::heap_profiler_connection() {
+  return heap_profiler_connection_.get();
+}
+
+inline void Environment::set_heap_prof_name(const std::string& name) {
+  heap_prof_name_ = name;
+}
+
+inline const std::string& Environment::heap_prof_name() const {
+  return heap_prof_name_;
+}
+
+inline void Environment::set_heap_prof_dir(const std::string& dir) {
+  heap_prof_dir_ = dir;
+}
+
+inline const std::string& Environment::heap_prof_dir() const {
+  return heap_prof_dir_;
+}
+
+inline void Environment::set_heap_prof_interval(uint64_t interval) {
+  heap_prof_interval_ = interval;
+}
+
+inline uint64_t Environment::heap_prof_interval() const {
+  return heap_prof_interval_;
+}
+
 #endif  // HAVE_INSPECTOR
 
 inline std::shared_ptr<HostPort> Environment::inspector_host_port() {

src/env.h

@@ -73,6 +73,7 @@ class AgentWriterHandle;
 namespace profiler {
 class V8CoverageConnection;
 class V8CpuProfilerConnection;
+class V8HeapProfilerConnection;
 }  // namespace profiler
 #endif  // HAVE_INSPECTOR
 
@@ -1151,6 +1152,20 @@ class Environment : public MemoryRetainer {
 
   inline void set_cpu_prof_dir(const std::string& dir);
   inline const std::string& cpu_prof_dir() const;
+
+  void set_heap_profiler_connection(
+      std::unique_ptr<profiler::V8HeapProfilerConnection> connection);
+  profiler::V8HeapProfilerConnection* heap_profiler_connection();
+
+  inline void set_heap_prof_name(const std::string& name);
+  inline const std::string& heap_prof_name() const;
+
+  inline void set_heap_prof_dir(const std::string& dir);
+  inline const std::string& heap_prof_dir() const;
+
+  inline void set_heap_prof_interval(uint64_t interval);
+  inline uint64_t heap_prof_interval() const;
+
 #endif  // HAVE_INSPECTOR
 
  private:
@@ -1190,6 +1205,10 @@ class Environment : public MemoryRetainer {
   std::string cpu_prof_dir_;
   std::string cpu_prof_name_;
   uint64_t cpu_prof_interval_;
+  std::unique_ptr<profiler::V8HeapProfilerConnection> heap_profiler_connection_;
+  std::string heap_prof_dir_;
+  std::string heap_prof_name_;
+  uint64_t heap_prof_interval_;
 #endif  // HAVE_INSPECTOR
 
   std::shared_ptr<EnvironmentOptions> options_;

src/inspector_profiler.cc

@@ -258,6 +258,44 @@ void V8CpuProfilerConnection::End() {
   DispatchMessage("Profiler.stop");
 }
 
+std::string V8HeapProfilerConnection::GetDirectory() const {
+  return env()->heap_prof_dir();
+}
+
+std::string V8HeapProfilerConnection::GetFilename() const {
+  return env()->heap_prof_name();
+}
+
+MaybeLocal<Object> V8HeapProfilerConnection::GetProfile(Local<Object> result) {
+  Local<Value> profile_v;
+  if (!result
+           ->Get(env()->context(),
+                 FIXED_ONE_BYTE_STRING(env()->isolate(), "profile"))
+           .ToLocal(&profile_v)) {
+    fprintf(stderr, "'profile' from heap profile result is undefined\n");
+    return MaybeLocal<Object>();
+  }
+  if (!profile_v->IsObject()) {
+    fprintf(stderr, "'profile' from heap profile result is not an Object\n");
+    return MaybeLocal<Object>();
+  }
+  return profile_v.As<Object>();
+}
+
+void V8HeapProfilerConnection::Start() {
+  DispatchMessage("HeapProfiler.enable");
+  std::string params = R"({ "samplingInterval": )";
+  params += std::to_string(env()->heap_prof_interval());
+  params += " }";
+  DispatchMessage("HeapProfiler.startSampling", params.c_str());
+}
+
+void V8HeapProfilerConnection::End() {
+  CHECK_EQ(ending_, false);
+  ending_ = true;
+  DispatchMessage("HeapProfiler.stopSampling");
+}
+
 // For now, we only support coverage profiling, but we may add more
 // in the future.
 void EndStartedProfilers(Environment* env) {
@@ -268,6 +306,12 @@ void EndStartedProfilers(Environment* env) {
     connection->End();
   }
 
+  connection = env->heap_profiler_connection();
+  if (connection != nullptr && !connection->ending()) {
+    Debug(env, DebugCategory::INSPECTOR_PROFILER, "Ending heap profiling\n");
+    connection->End();
+  }
+
   connection = env->coverage_connection();
   if (connection != nullptr && !connection->ending()) {
     Debug(
@@ -313,6 +357,20 @@ void StartProfilers(Environment* env) {
         std::make_unique<V8CpuProfilerConnection>(env));
     env->cpu_profiler_connection()->Start();
   }
+  if (env->options()->heap_prof) {
+    const std::string& dir = env->options()->heap_prof_dir;
+    env->set_heap_prof_interval(env->options()->heap_prof_interval);
+    env->set_heap_prof_dir(dir.empty() ? GetCwd() : dir);
+    if (env->options()->heap_prof_name.empty()) {
+      DiagnosticFilename filename(env, "Heap", "heapprofile");
+      env->set_heap_prof_name(*filename);
+    } else {
+      env->set_heap_prof_name(env->options()->heap_prof_name);
+    }
+    env->set_heap_profiler_connection(
+        std::make_unique<profiler::V8HeapProfilerConnection>(env));
+    env->heap_profiler_connection()->Start();
+  }
 }
 
 static void SetCoverageDirectory(const FunctionCallbackInfo<Value>& args) {

src/inspector_profiler.h

@@ -107,6 +107,26 @@ class V8CpuProfilerConnection : public V8ProfilerConnection {
   bool ending_ = false;
 };
 
+class V8HeapProfilerConnection : public V8ProfilerConnection {
+ public:
+  explicit V8HeapProfilerConnection(Environment* env)
+      : V8ProfilerConnection(env) {}
+
+  void Start() override;
+  void End() override;
+
+  const char* type() const override { return "heap"; }
+  bool ending() const override { return ending_; }
+
+  std::string GetDirectory() const override;
+  std::string GetFilename() const override;
+  v8::MaybeLocal<v8::Object> GetProfile(v8::Local<v8::Object> result) override;
+
+ private:
+  std::unique_ptr<inspector::InspectorSession> session_;
+  bool ending_ = false;
+};
+
 }  // namespace profiler
 }  // namespace node
 

src/node_options.cc

@@ -168,6 +168,19 @@ void EnvironmentOptions::CheckOptions(std::vector<std::string>* errors) {
     }
   }
 
+  if (!heap_prof) {
+    if (!heap_prof_name.empty()) {
+      errors->push_back("--heap-prof-name must be used with --heap-prof");
+    }
+    if (!heap_prof_dir.empty()) {
+      errors->push_back("--heap-prof-dir must be used with --heap-prof");
+    }
+    // We can't catch the case where the value passed is the default value,
+    // then the option just becomes a noop which is fine.
+    if (heap_prof_interval != kDefaultHeapProfInterval) {
+      errors->push_back("--heap-prof-interval must be used with --heap-prof");
+    }
+  }
   debug_options_.CheckOptions(errors);
 #endif  // HAVE_INSPECTOR
 }
@@ -374,6 +387,24 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "Directory where the V8 profiles generated by --cpu-prof will be "
             "placed. Does not affect --prof.",
             &EnvironmentOptions::cpu_prof_dir);
+  AddOption(
+      "--heap-prof",
+      "Start the V8 heap profiler on start up, and write the heap profile "
+      "to disk before exit. If --heap-prof-dir is not specified, write "
+      "the profile to the current working directory.",
+      &EnvironmentOptions::heap_prof);
+  AddOption("--heap-prof-name",
+            "specified file name of the V8 CPU profile generated with "
+            "--heap-prof",
+            &EnvironmentOptions::heap_prof_name);
+  AddOption("--heap-prof-dir",
+            "Directory where the V8 heap profiles generated by --heap-prof "
+            "will be placed.",
+            &EnvironmentOptions::heap_prof_dir);
+  AddOption("--heap-prof-interval",
+            "specified sampling interval in bytes for the V8 heap "
+            "profile generated with --heap-prof. (default: 512 * 1024)",
+            &EnvironmentOptions::heap_prof_interval);
 #endif  // HAVE_INSPECTOR
   AddOption("--redirect-warnings",
             "write warnings to file instead of stderr",

src/node_options.h

@@ -116,6 +116,11 @@ class EnvironmentOptions : public Options {
   uint64_t cpu_prof_interval = kDefaultCpuProfInterval;
   std::string cpu_prof_name;
   bool cpu_prof = false;
+  std::string heap_prof_dir;
+  std::string heap_prof_name;
+  static const uint64_t kDefaultHeapProfInterval = 512 * 1024;
+  uint64_t heap_prof_interval = kDefaultHeapProfInterval;
+  bool heap_prof = false;
 #endif  // HAVE_INSPECTOR
   std::string redirect_warnings;
   bool throw_deprecation = false;

test/fixtures/workload/allocation-exit.js

@@ -0,0 +1,17 @@
+'use strict';
+
+const util = require('util');
+const total = parseInt(process.env.TEST_ALLOCATION) || 100;
+let count = 0;
+let string = '';
+function runAllocation() {
+  string += util.inspect(process.env);
+  if (count++ < total) {
+    setTimeout(runAllocation, 1);
+  } else {
+    console.log(string.length);
+    process.exit(55);
+  }
+}
+
+setTimeout(runAllocation, 1);

test/fixtures/workload/allocation-sigint.js

@@ -0,0 +1,17 @@
+'use strict';
+
+const util = require('util');
+const total = parseInt(process.env.TEST_ALLOCATION) || 100;
+let count = 0;
+let string = '';
+function runAllocation() {
+  string += util.inspect(process.env);
+  if (count++ < total) {
+    setTimeout(runAllocation, 1);
+  } else {
+    console.log(string.length);
+    process.kill(process.pid, "SIGINT");
+  }
+}
+
+setTimeout(runAllocation, 1);

test/fixtures/workload/allocation-worker-argv.js

@@ -0,0 +1,11 @@
+'use strict';
+
+const { Worker } = require('worker_threads');
+const path = require('path');
+new Worker(path.join(__dirname, 'allocation.js'), {
+  execArgv: [
+    '--heap-prof',
+    '--heap-prof-interval',
+    process.HEAP_PROF_INTERVAL || '128',
+  ]
+});

test/fixtures/workload/allocation-worker.js

@@ -0,0 +1,5 @@
+'use strict';
+
+const { Worker } = require('worker_threads');
+const path = require('path');
+new Worker(path.join(__dirname, 'allocation.js'));