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v8: support gc profile · nodejs/node@02632b4 · GitHub

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juanarbol
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v8: support gc profile
PR-URL: #46255 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com> Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
1 parent 63e92ea commit 02632b4

8 files changed

Lines changed: 460 additions & 1 deletion

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‎doc/api/v8.md‎

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Original file line numberDiff line numberDiff line change
@@ -1021,6 +1021,112 @@ added: v18.6.0
10211021

10221022
Returns true if the Node.js instance is run to build a snapshot.
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## Class: `v8.GCProfiler`
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<!-- YAML
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added: REPLACEME
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-->
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This API collects GC data in current thread.
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### `new v8.GCProfiler()`
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<!-- YAML
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added: REPLACEME
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-->
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Create a new instance of the `v8.GCProfiler` class.
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### `profiler.start()`
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<!-- YAML
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added: REPLACEME
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-->
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Start collecting GC data.
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### `profiler.stop()`
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<!-- YAML
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added: REPLACEME
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-->
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Stop collecting GC data and return a object.The content of object
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is as follows.
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```json
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{
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"version": 1,
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"startTime": 1674059033862,
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"statistics": [
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{
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"gcType": "Scavenge",
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"beforeGC": {
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"heapStatistics": {
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"totalHeapSize": 5005312,
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"totalHeapSizeExecutable": 524288,
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"totalPhysicalSize": 5226496,
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"totalAvailableSize": 4341325216,
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"totalGlobalHandlesSize": 8192,
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"usedGlobalHandlesSize": 2112,
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"usedHeapSize": 4883840,
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"heapSizeLimit": 4345298944,
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"mallocedMemory": 254128,
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"externalMemory": 225138,
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"peakMallocedMemory": 181760
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},
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"heapSpaceStatistics": [
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{
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"spaceName": "read_only_space",
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"spaceSize": 0,
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"spaceUsedSize": 0,
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"spaceAvailableSize": 0,
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"physicalSpaceSize": 0
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}
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]
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},
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"cost": 1574.14,
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"afterGC": {
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"heapStatistics": {
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"totalHeapSize": 6053888,
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"totalHeapSizeExecutable": 524288,
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"totalPhysicalSize": 5500928,
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"totalAvailableSize": 4341101384,
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"totalGlobalHandlesSize": 8192,
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"usedGlobalHandlesSize": 2112,
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"usedHeapSize": 4059096,
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"heapSizeLimit": 4345298944,
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"mallocedMemory": 254128,
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"externalMemory": 225138,
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"peakMallocedMemory": 181760
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},
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"heapSpaceStatistics": [
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{
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"spaceName": "read_only_space",
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"spaceSize": 0,
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"spaceUsedSize": 0,
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"spaceAvailableSize": 0,
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"physicalSpaceSize": 0
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}
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]
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}
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}
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],
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"endTime": 1674059036865
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}
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```
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Here's an example.
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```js
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const { GCProfiler } = require('v8');
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const profiler = new GCProfiler();
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profiler.start();
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setTimeout(() => {
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console.log(profiler.stop());
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}, 1000);
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```
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[HTML structured clone algorithm]: https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm
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[Hook Callbacks]: #hook-callbacks
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[V8]: https://developers.google.com/v8/

‎lib/v8.js‎

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Original file line numberDiff line numberDiff line change
@@ -60,7 +60,7 @@ const {
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const { HeapSnapshotStream } = require('internal/heap_utils');
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const promiseHooks = require('internal/promise_hooks');
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const { getOptionValue } = require('internal/options');
63-
63+
const { JSONParse } = primordials;
6464
/**
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* Generates a snapshot of the current V8 heap
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* and writes it to a JSON file.
@@ -384,6 +384,25 @@ function deserialize(buffer) {
384384
return der.readValue();
385385
}
386386

387+
class GCProfiler {
388+
#profiler = null;
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start() {
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if (!this.#profiler) {
392+
this.#profiler = new binding.GCProfiler();
393+
this.#profiler.start();
394+
}
395+
}
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397+
stop() {
398+
if (this.#profiler) {
399+
const data = this.#profiler.stop();
400+
this.#profiler = null;
401+
return JSONParse(data);
402+
}
403+
}
404+
}
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387406
module.exports = {
388407
cachedDataVersionTag,
389408
getHeapSnapshot,
@@ -403,4 +422,5 @@ module.exports = {
403422
promiseHooks,
404423
startupSnapshot,
405424
setHeapSnapshotNearHeapLimit,
425+
GCProfiler,
406426
};

‎src/node_v8.cc‎

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Original file line numberDiff line numberDiff line change
@@ -33,6 +33,7 @@ namespace v8_utils {
3333
using v8::Array;
3434
using v8::Context;
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using v8::FunctionCallbackInfo;
36+
using v8::FunctionTemplate;
3637
using v8::HandleScope;
3738
using v8::HeapCodeStatistics;
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using v8::HeapSpaceStatistics;
@@ -210,6 +211,184 @@ void SetFlagsFromString(const FunctionCallbackInfo<Value>& args) {
210211
V8::SetFlagsFromString(*flags, static_cast<size_t>(flags.length()));
211212
}
212213

214+
static const char* GetGCTypeName(v8::GCType gc_type) {
215+
switch (gc_type) {
216+
case v8::GCType::kGCTypeScavenge:
217+
return "Scavenge";
218+
case v8::GCType::kGCTypeMarkSweepCompact:
219+
return "MarkSweepCompact";
220+
case v8::GCType::kGCTypeIncrementalMarking:
221+
return "IncrementalMarking";
222+
case v8::GCType::kGCTypeProcessWeakCallbacks:
223+
return "ProcessWeakCallbacks";
224+
default:
225+
return "Unknown";
226+
}
227+
}
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229+
static void SetHeapStatistics(JSONWriter* writer, Isolate* isolate) {
230+
HeapStatistics heap_statistics;
231+
isolate->GetHeapStatistics(&heap_statistics);
232+
writer->json_objectstart("heapStatistics");
233+
writer->json_keyvalue("totalHeapSize", heap_statistics.total_heap_size());
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writer->json_keyvalue("totalHeapSizeExecutable",
235+
heap_statistics.total_heap_size_executable());
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writer->json_keyvalue("totalPhysicalSize",
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heap_statistics.total_physical_size());
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writer->json_keyvalue("totalAvailableSize",
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heap_statistics.total_available_size());
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writer->json_keyvalue("totalGlobalHandlesSize",
241+
heap_statistics.total_global_handles_size());
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writer->json_keyvalue("usedGlobalHandlesSize",
243+
heap_statistics.used_global_handles_size());
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writer->json_keyvalue("usedHeapSize", heap_statistics.used_heap_size());
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writer->json_keyvalue("heapSizeLimit", heap_statistics.heap_size_limit());
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writer->json_keyvalue("mallocedMemory", heap_statistics.malloced_memory());
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writer->json_keyvalue("externalMemory", heap_statistics.external_memory());
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writer->json_keyvalue("peakMallocedMemory",
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heap_statistics.peak_malloced_memory());
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writer->json_objectend();
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252+
int space_count = isolate->NumberOfHeapSpaces();
253+
writer->json_arraystart("heapSpaceStatistics");
254+
for (int i = 0; i < space_count; i++) {
255+
HeapSpaceStatistics heap_space_statistics;
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isolate->GetHeapSpaceStatistics(&heap_space_statistics, i);
257+
writer->json_start();
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writer->json_keyvalue("spaceName", heap_space_statistics.space_name());
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writer->json_keyvalue("spaceSize", heap_space_statistics.space_size());
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writer->json_keyvalue("spaceUsedSize",
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heap_space_statistics.space_used_size());
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writer->json_keyvalue("spaceAvailableSize",
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heap_space_statistics.space_available_size());
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writer->json_keyvalue("physicalSpaceSize",
265+
heap_space_statistics.physical_space_size());
266+
writer->json_end();
267+
}
268+
writer->json_arrayend();
269+
}
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271+
static void BeforeGCCallback(Isolate* isolate,
272+
v8::GCType gc_type,
273+
v8::GCCallbackFlags flags,
274+
void* data) {
275+
GCProfiler* profiler = static_cast<GCProfiler*>(data);
276+
if (profiler->current_gc_type != 0) {
277+
return;
278+
}
279+
JSONWriter* writer = profiler->writer();
280+
writer->json_start();
281+
writer->json_keyvalue("gcType", GetGCTypeName(gc_type));
282+
writer->json_objectstart("beforeGC");
283+
SetHeapStatistics(writer, isolate);
284+
writer->json_objectend();
285+
profiler->current_gc_type = gc_type;
286+
profiler->start_time = uv_hrtime();
287+
}
288+
289+
static void AfterGCCallback(Isolate* isolate,
290+
v8::GCType gc_type,
291+
v8::GCCallbackFlags flags,
292+
void* data) {
293+
GCProfiler* profiler = static_cast<GCProfiler*>(data);
294+
if (profiler->current_gc_type != gc_type) {
295+
return;
296+
}
297+
JSONWriter* writer = profiler->writer();
298+
profiler->current_gc_type = 0;
299+
writer->json_keyvalue("cost", (uv_hrtime() - profiler->start_time) / 1e3);
300+
profiler->start_time = 0;
301+
writer->json_objectstart("afterGC");
302+
SetHeapStatistics(writer, isolate);
303+
writer->json_objectend();
304+
writer->json_end();
305+
}
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307+
GCProfiler::GCProfiler(Environment* env, Local<Object> object)
308+
: BaseObject(env, object),
309+
start_time(0),
310+
current_gc_type(0),
311+
state(GCProfilerState::kInitialized),
312+
writer_(out_stream_, false) {
313+
MakeWeak();
314+
}
315+
316+
// This function will be called when
317+
// 1. StartGCProfile and StopGCProfile are called and
318+
// JS land does not keep the object anymore.
319+
// 2. StartGCProfile is called then the env exits before
320+
// StopGCProfile is called.
321+
GCProfiler::~GCProfiler() {
322+
if (state != GCProfiler::GCProfilerState::kInitialized) {
323+
env()->isolate()->RemoveGCPrologueCallback(BeforeGCCallback, this);
324+
env()->isolate()->RemoveGCEpilogueCallback(AfterGCCallback, this);
325+
}
326+
}
327+
328+
JSONWriter* GCProfiler::writer() {
329+
return &writer_;
330+
}
331+
332+
std::ostringstream* GCProfiler::out_stream() {
333+
return &out_stream_;
334+
}
335+
336+
void GCProfiler::New(const FunctionCallbackInfo<Value>& args) {
337+
CHECK(args.IsConstructCall());
338+
Environment* env = Environment::GetCurrent(args);
339+
new GCProfiler(env, args.This());
340+
}
341+
342+
void GCProfiler::Start(const FunctionCallbackInfo<Value>& args) {
343+
Environment* env = Environment::GetCurrent(args);
344+
GCProfiler* profiler;
345+
ASSIGN_OR_RETURN_UNWRAP(&profiler, args.Holder());
346+
if (profiler->state != GCProfiler::GCProfilerState::kInitialized) {
347+
return;
348+
}
349+
profiler->writer()->json_start();
350+
profiler->writer()->json_keyvalue("version", 1);
351+
352+
uv_timeval64_t ts;
353+
if (uv_gettimeofday(&ts) == 0) {
354+
profiler->writer()->json_keyvalue("startTime",
355+
ts.tv_sec * 1000 + ts.tv_usec / 1000);
356+
} else {
357+
profiler->writer()->json_keyvalue("startTime", 0);
358+
}
359+
profiler->writer()->json_arraystart("statistics");
360+
env->isolate()->AddGCPrologueCallback(BeforeGCCallback,
361+
static_cast<void*>(profiler));
362+
env->isolate()->AddGCEpilogueCallback(AfterGCCallback,
363+
static_cast<void*>(profiler));
364+
profiler->state = GCProfiler::GCProfilerState::kStarted;
365+
}
366+
367+
void GCProfiler::Stop(const FunctionCallbackInfo<v8::Value>& args) {
368+
Environment* env = Environment::GetCurrent(args);
369+
GCProfiler* profiler;
370+
ASSIGN_OR_RETURN_UNWRAP(&profiler, args.Holder());
371+
if (profiler->state != GCProfiler::GCProfilerState::kStarted) {
372+
return;
373+
}
374+
profiler->writer()->json_arrayend();
375+
uv_timeval64_t ts;
376+
if (uv_gettimeofday(&ts) == 0) {
377+
profiler->writer()->json_keyvalue("endTime",
378+
ts.tv_sec * 1000 + ts.tv_usec / 1000);
379+
} else {
380+
profiler->writer()->json_keyvalue("endTime", 0);
381+
}
382+
profiler->writer()->json_end();
383+
profiler->state = GCProfiler::GCProfilerState::kStopped;
384+
auto string = profiler->out_stream()->str();
385+
args.GetReturnValue().Set(String::NewFromUtf8(env->isolate(),
386+
string.data(),
387+
v8::NewStringType::kNormal,
388+
string.size())
389+
.ToLocalChecked());
390+
}
391+
213392
void Initialize(Local<Object> target,
214393
Local<Value> unused,
215394
Local<Context> context,
@@ -272,6 +451,14 @@ void Initialize(Local<Object> target,
272451

273452
// Export symbols used by v8.setFlagsFromString()
274453
SetMethod(context, target, "setFlagsFromString", SetFlagsFromString);
454+
455+
// GCProfiler
456+
Local<FunctionTemplate> t =
457+
NewFunctionTemplate(env->isolate(), GCProfiler::New);
458+
t->InstanceTemplate()->SetInternalFieldCount(BaseObject::kInternalFieldCount);
459+
SetProtoMethod(env->isolate(), t, "start", GCProfiler::Start);
460+
SetProtoMethod(env->isolate(), t, "stop", GCProfiler::Stop);
461+
SetConstructorFunction(context, target, "GCProfiler", t);
275462
}
276463

277464
void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
@@ -281,6 +468,9 @@ void RegisterExternalReferences(ExternalReferenceRegistry* registry) {
281468
registry->Register(UpdateHeapSpaceStatisticsBuffer);
282469
registry->Register(SetFlagsFromString);
283470
registry->Register(SetHeapSnapshotNearHeapLimit);
471+
registry->Register(GCProfiler::New);
472+
registry->Register(GCProfiler::Start);
473+
registry->Register(GCProfiler::Stop);
284474
}
285475

286476
} // namespace v8_utils

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