Node.js cluster demo

cluster.js

const cluster = require('cluster');
const os = require('os');

const pid = process.pid;
const cpusCount = os.cpus().length;

if (cluster.isMaster) {
  console.log(`CPUs: ${cpusCount}`);
  console.log(`Master started. Pid: ${pid}`);
  for (let i = 0; i < cpusCount - 1; i++) {
    const worker = cluster.fork();
  }

  cluster.on('fork', (worker) => {
    // console.log(`Worker #${worker.id} is forked =)`);
  });


  cluster.on('online', (worker) => {
    console.log(`Worker #${worker.id} with pid ${worker.process.pid} is online =)`);
  });

  cluster.on('listening', (worker, address) => {
    // console.log(`The worker #${worker.id} is now connected to ${JSON.stringify(address)}`);
  });


  cluster.on('disconnect', (worker) => {
    console.log(`The worker #${worker.id} has disconnected`);
  });

  cluster.on('exit', (worker, code) => {
    console.log(`Worker died! Pid: ${worker.process.pid}. Code ${code}`);
    if (code === 1) {
      cluster.fork();
    }
  });

  cluster.on('message', (worker, message, handle) => {});
}

if (cluster.isWorker) {
    require('./worker.js');
}

handler.js

module.exports = (req, res) => {
  for (let i = 0; i < 1e7; i++) {}
  res.end('end');
}

index.js

require('./cluster');

worker.js

const http = require('http');
const handler = require('./handler');

// const pid = process.pid;
const port = process.env.PORT || 3000;

const server = http
  .createServer(handler)
  .listen(port, () => {
      // console.log(`Worker started. Pid: ${pid}`);
  });

// https://nodejs.org/dist/latest-v10.x/docs/api/process.html#process_event_uncaughtexception
process.on('uncaughtException', (err) => {
  console.error(`${(new Date).toUTCString()} uncaught exception: ${err.message}`);
  console.error(err.stack);
  process.exit(1);
});

// https://nodejs.org/dist/latest-v10.x/docs/api/process.html#process_event_unhandledrejection
process.on('unhandledRejection', (reason, p) => {
  console.log('Unhandled Rejection at:', p, 'reason:', reason);
  console.error(`${(new Date).toUTCString()}. ${reason.message}`);
  console.error(reason.stack);
  process.exit(1);
});

// https://nodejs.org/dist/latest-v10.x/docs/api/process.html#process_signal_events
process.on('SIGINT', () => {
  console.log('Signal is SIGINT');
  server.close(() => {
    process.exit(0);
  })
});

process.on('SIGTERM', () => {
  console.log('Signal is SIGTERM');
  server.close(() => {
    process.exit(0);
  })
});

process.on('SIGUSR2', () => {
  console.log('Signal is SIGUSR2');
  server.close(() => {
    process.exit(1);
  })
});