const cluster = require('cluster');
const http = require('http');
const os = require('os');
if (cluster.isMaster) {
const numCPUs = os.cpus().length;
console.log(`Master ${process.pid} is running`);
for (let i = 0; i < numCPUs; i++) {
cluster.fork();
}
cluster.on('exit', (worker, code, signal) => {
console.log(`Worker ${worker.process.pid} died`);
cluster.fork();
});
} else {
http.createServer((req, res) => {
res.writeHead(200);
res.end('Hello World!');
}).listen(3000);
console.log(`Worker ${process.pid} started`);
}