node profiler

index.ts

import inspector from 'inspector';
import { writeFile } from 'fs/promises';
import cron from 'node-cron';

class Profiler {
  private session: inspector.Session;

  constructor() {
    this.session = new inspector.Session();
  }

  public async connect() {
    this.session.connect();
  }

  public async startCpuProfiling() {
    await this.sessionPost('Profiler.enable');
    await this.sessionPost('Profiler.start');
  }

  public async stopCpuProfiling() {
    const { profile } = await this.sessionPost<inspector.Profiler.StopReturnType>('Profiler.stop');
    await this.sessionPost('Profiler.disable');
    return profile;
  }

  public async disconnect() {
    this.session.disconnect();
  }

  private async sessionPost<T>(method: string, params?: any): Promise<T> {
    return new Promise((resolve, reject) => {
      this.session.post(method, params, (error, result) => {
        if (error) reject(error);
        else resolve(result as T);
      });
    });
  }
}

async function main() {
  cron.schedule('*/10 * * * * *', async () => {
    const profiler = new Profiler();

    await profiler.connect();
    await profiler.startCpuProfiling();

    await new Promise(resolve => setTimeout(resolve, 5000));

    const profile = await profiler.stopCpuProfiling();
    await profiler.disconnect();

    await writeFile('profile.cpuprofile', JSON.stringify(profile));
  });

  setInterval(function doWork() {
    const date = Date.now();
    const delay = Math.floor(Math.random() * 200);
    while (Date.now() < date + delay) {
      // do nothing
    }
  }, 100);
}

main();