v8: add cpu profile

Author: theanarkh

doc/api/v8.md

@@ -1398,6 +1398,30 @@ setTimeout(() => {
 }, 1000);
 ```
 
+## Class: `SyncCPUProfileHandle`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+### `syncCpuProfileHandle.stop()`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* Returns: {string}
+
+Stopping collecting the profile and return the profile data.
+
+### `syncCpuProfileHandle[Symbol.dispose]()`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+Stopping collecting the profile and the profile will be discarded.
+
 ## Class: `CPUProfileHandle`
 
 <!-- YAML
@@ -1493,6 +1517,23 @@ writeString('hello');
 writeString('你好');
 ```
 
+## `v8.startCpuProfile()`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* Returns: {SyncCPUProfileHandle}
+
+Starting a CPU profile then return a `SyncCPUProfileHandle` object.
+This API supports `using` syntax.
+
+```cjs
+const handle = v8.startCpuProfile();
+const profile = handle.stop();
+console.log(profile);
+```
+
 [CppHeap]: https://v8docs.nodesource.com/node-22.4/d9/dc4/classv8_1_1_cpp_heap.html
 [HTML structured clone algorithm]: https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm
 [Hook Callbacks]: #hook-callbacks

lib/v8.js

@@ -27,6 +27,7 @@ const {
   Int8Array,
   JSONParse,
   ObjectPrototypeToString,
+  SymbolDispose,
   Uint16Array,
   Uint32Array,
   Uint8Array,
@@ -112,6 +113,8 @@ const binding = internalBinding('v8');
 const {
   cachedDataVersionTag,
   setFlagsFromString: _setFlagsFromString,
+  startCpuProfile: _startCpuProfile,
+  stopCpuProfile: _stopCpuProfile,
   isStringOneByteRepresentation: _isStringOneByteRepresentation,
   updateHeapStatisticsBuffer,
   updateHeapSpaceStatisticsBuffer,
@@ -166,6 +169,36 @@ function setFlagsFromString(flags) {
   _setFlagsFromString(flags);
 }
 
+class SyncCPUProfileHandle {
+  #id = null;
+  #stopped = false;
+
+  constructor(id) {
+    this.#id = id;
+  }
+
+  stop() {
+    if (this.#stopped) {
+      return;
+    }
+    this.#stopped = true;
+    return _stopCpuProfile(this.#id);
+  };
+
+  [SymbolDispose]() {
+    this.stop();
+  }
+}
+
+/**
+ * Starting CPU Profile.
+ * @returns {SyncCPUProfileHandle}
+ */
+function startCpuProfile() {
+  const id = _startCpuProfile();
+  return new SyncCPUProfileHandle(id);
+}
+
 /**
  * Return whether this string uses one byte as underlying representation or not.
  * @param {string} content
@@ -478,4 +511,5 @@ module.exports = {
   setHeapSnapshotNearHeapLimit,
   GCProfiler,
   isStringOneByteRepresentation,
+  startCpuProfile,
 };

src/node_v8.cc

@@ -27,6 +27,7 @@
 #include "node.h"
 #include "node_external_reference.h"
 #include "util-inl.h"
+#include "v8-profiler.h"
 #include "v8.h"
 
 namespace node {
@@ -35,6 +36,9 @@ using v8::Array;
 using v8::BigInt;
 using v8::CFunction;
 using v8::Context;
+using v8::CpuProfile;
+using v8::CpuProfilingResult;
+using v8::CpuProfilingStatus;
 using v8::DictionaryTemplate;
 using v8::FunctionCallbackInfo;
 using v8::FunctionTemplate;
@@ -47,6 +51,7 @@ using v8::Isolate;
 using v8::Local;
 using v8::LocalVector;
 using v8::MaybeLocal;
+using v8::Number;
 using v8::Object;
 using v8::ScriptCompiler;
 using v8::String;
@@ -241,6 +246,39 @@ void SetFlagsFromString(const FunctionCallbackInfo<Value>& args) {
   V8::SetFlagsFromString(*flags, static_cast<size_t>(flags.length()));
 }
 
+void StartCpuProfile(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+  Isolate* isolate = env->isolate();
+  CpuProfilingResult result = env->StartCpuProfile();
+  if (result.status == CpuProfilingStatus::kErrorTooManyProfilers) {
+    return THROW_ERR_CPU_PROFILE_TOO_MANY(isolate,
+                                          "There are too many CPU profiles");
+  } else if (result.status == CpuProfilingStatus::kStarted) {
+    args.GetReturnValue().Set(Number::New(isolate, result.id));
+  }
+}
+
+void StopCpuProfile(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+  Isolate* isolate = env->isolate();
+  CHECK(args[0]->IsUint32());
+  uint32_t profile_id = args[0]->Uint32Value(env->context()).FromJust();
+  CpuProfile* profile = env->StopCpuProfile(profile_id);
+  if (!profile) {
+    return THROW_ERR_CPU_PROFILE_NOT_STARTED(isolate,
+                                             "CPU profile not started");
+  }
+  auto json_out_stream = std::make_unique<node::JSONOutputStream>();
+  profile->Serialize(json_out_stream.get(),
+                     CpuProfile::SerializationFormat::kJSON);
+  profile->Delete();
+  Local<Value> ret;
+  if (ToV8Value(env->context(), json_out_stream->out_stream().str(), isolate)
+          .ToLocal(&ret)) {
+    args.GetReturnValue().Set(ret);
+  }
+}
+
 static void IsStringOneByteRepresentation(
     const FunctionCallbackInfo<Value>& args) {
   CHECK_EQ(args.Length(), 1);
@@ -699,6 +737,9 @@ void Initialize(Local<Object> target,
   // Export symbols used by v8.setFlagsFromString()
   SetMethod(context, target, "setFlagsFromString", SetFlagsFromString);
 
+  SetMethod(context, target, "startCpuProfile", StartCpuProfile);
+  SetMethod(context, target, "stopCpuProfile", StopCpuProfile);
+
   // Export symbols used by v8.isStringOneByteRepresentation()
   SetFastMethodNoSideEffect(context,
                             target,
@@ -743,6 +784,8 @@ void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
   registry->Register(GetCppHeapStatistics);
   registry->Register(IsStringOneByteRepresentation);
   registry->Register(fast_is_string_one_byte_representation_);
+  registry->Register(StartCpuProfile);
+  registry->Register(StopCpuProfile);
 }
 
 }  // namespace v8_utils

src/node_v8.h

@@ -7,6 +7,7 @@
 #include "aliased_buffer.h"
 #include "base_object.h"
 #include "json_utils.h"
+#include "node_errors.h"
 #include "node_snapshotable.h"
 #include "util.h"
 #include "v8.h"

test/parallel/test-v8-cpu-profile.js

@@ -0,0 +1,12 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+const v8 = require('v8');
+
+const handle = v8.startCpuProfile();
+const profile = handle.stop();
+assert.ok(typeof profile === 'string');
+assert.ok(profile.length > 0);
+// Call stop() again
+assert.ok(handle.stop() === undefined);

tools/doc/type-parser.mjs

@@ -352,6 +352,7 @@ const customTypesMap = {
   'LockManagerSnapshot': 'https://developer.mozilla.org/en-US/docs/Web/API/LockManagerSnapshot',
   'CPUProfileHandle': 'v8.html#class-cpuprofilehandle',
   'HeapProfileHandle': 'v8.html#class-heapprofilehandle',
+  'SyncCPUProfileHandle': 'v8.html#class-synccpuprofilehandle',
 };
 
 const arrayPart = /(?:\[])+$/;