v8-profiler-next

node bindings for the v8 profiler

Usage no npm install needed!

<script type="module">
  import v8ProfilerNext from 'https://cdn.skypack.dev/v8-profiler-next';
</script>

README

v8-profiler-next

npm version Package Quality Linux/osx build status windows build status downloads info license

Description

v8-profiler-next provides node bindings for the v8 profiler.

I. Quick Start

  • Compatibility
    • node version: v4.x ~ v16.x
    • platform: mac, linux, windows

take cpu profile

'use strict';
const v8Profiler = require('v8-profiler-next');
const title = 'good-name';
// ex. 5 mins cpu profile
v8Profiler.startProfiling(title, true);
setTimeout(() => {
  const profile = v8Profiler.stopProfiling(title);
  profile.export(function (error, result) {
    // if it doesn't have the extension .cpuprofile then
    // chrome's profiler tool won't like it.
    // examine the profile:
    //   Navigate to chrome://inspect
    //   Click Open dedicated DevTools for Node
    //   Select the profiler tab
    //   Load your file
    fs.writeFileSync(`${title}.cpuprofile`, result);
    profile.delete();
  });
}, 5 * 60 * 1000);

take heapsnapshot

'use strict';
const v8Profiler = require('v8-profiler-next');
const snapshot = v8Profiler.takeSnapshot();
// 1. not as stream
snapshot.export(function (error, result) {
    if (error){
        console.error(error);
        return;
    }
    console.log(result);
    snapshot.delete();
});
// 2. as stream
const transform = snapshot.export();
transform.pipe(process.stdout);
transform.on('finish', snapshot.delete.bind(snapshot));

take allocation profile

Attention: If node version < v12.x, please use sampling heap profiling alone without cpu profiling or taking snapshot.

'use strict';
const v8Profiler = require('v8-profiler-next');
// set a leak array
const arraytest = [];
setInterval(() => {
  arraytest.push(new Array(1e2).fill('*').join());
}, 20);
// start 1min sampling profile
v8Profiler.startSamplingHeapProfiling();
setTimeout(() => {
    // stop and get allocation profile
    const profile = v8Profiler.stopSamplingHeapProfiling();
    // upload shf.heapprofile into chrome dev tools -> Memory -> ALLOCATION PRODILES
  require('fs').writeFileSync('./shf.heapprofile', JSON.stringify(profile));
    console.log(profile);
}, 60 * 1000);

II. License

MIT License

Copyright (c) 2018 team of v8-profiler, hyj1991