index.js

const v8Profiler = require('v8-profiler-next');
const Koa = require('koa');
const Router = require('koa-router');
const fs = require('fs');
const {promisify} = require('util');

const writeFile = promisify(fs.writeFile);

let app = new Koa();
let router = new Router();

router.get('/', (ctx, next) => {
  // ctx.router available
  ctx.body = 'ok';
});

router.get('/start-profiling', (ctx, next) => {
  v8Profiler.startProfiling('p1');
  ctx.body = 'started';
});

router.get('/stop-profiling', async (ctx, next) => {
  const result = v8Profiler.stopProfiling('p1');
  if (result) {
    await writeFile('./v8-profile.json', JSON.stringify(result));
    ctx.body = 'saved profile';
  } else {
    ctx.body = 'nothing to show';
  }
});

app
  .use(router.routes())
  .use(router.allowedMethods());

app.listen(3000);