master process in nodejs code example

Example 1: node cluster

const cluster = require('cluster');
const http = require('http');
const numCPUs = require('os').cpus().length;

if (cluster.isMaster) {
  console.log(`Master ${process.pid} is running`);

  // Fork workers.
  for (let i = 0; i < numCPUs; i++) {
    cluster.fork();
  }

  cluster.on('exit', (worker, code, signal) => {
    console.log(`worker ${worker.process.pid} died`);
  });
} else {
  // Workers can share any TCP connection
  // In this case it is an HTTP server
  http.createServer((req, res) => {
    res.writeHead(200);
    res.end('hello world\n');
  }).listen(8000);

  console.log(`Worker ${process.pid} started`);
}

Example 2: nodejs cluster example

import http, { Server } from 'http'
import cluster, { Worker } from 'cluster'
import { cpus, CpuInfo } from 'os'
import consola from 'consola'
import chalk from 'chalk'
import app from './src/app'

const coreThread: CpuInfo[] = cpus()

if (cluster.isMaster) {
	for (let i = 0; i < coreThread.length; i++) {
		cluster.fork()
	}

	const workersTread: any = []
	for (const id in cluster.workers) {
		workersTread.push(id)
	}

	workersTread.forEach(
		async (pid: number, _: number): Promise<void> => {
			await cluster.workers[pid].send({
				from: 'isMaster',
				type: 'SIGKILL',
				message: 'cleanup is worker dead and change to new worker'
			})
		}
	)

	if (process.env.NODE_ENV !== 'production') {
		cluster.on('online', (worker: Worker): void => {
			if (worker.isConnected()) {
				console.info(`${chalk.greenBright('worker active pid')}: ${worker.process.pid}`)
			}
		})

		cluster.on('exit', (worker: Worker, code: number, signal: string): void => {
			if (worker.isDead()) {
				console.info(`${chalk.redBright('worker dead pid')}: ${worker.process.pid}`)
			}
			cluster.fork()
		})
	}
} else {
	const server = http.createServer(app) as Server
	const host: any = process.env.HOST
	const port: any = process.env.PORT
	server.listen(port, host, (): void => consola.success(`server is running on ${port}`))
}