Explain the differences between clustering and launching subprocesses in a system.

Clustering and spawning child processes are two ways to scale and manage processes in Node.js, but they have different goals and mechanisms.

Clustering is a built-in Node.js module that allows creating multiple worker processes, each running a copy of your server. It is used for efficient utilization of multi-core processors, as Node.js is single-threaded by default. Clustering automatically distributes incoming requests among the workers.

Child processes are created using the child_process module and allow running separate processes to perform tasks that may be heavy or blocking, such as executing scripts, commands, or other programs. They are not necessarily related to handling HTTP requests.

Example of using clustering:

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

if (cluster.isMaster) {
  for (let i = 0; i < numCPUs; i++) {
    cluster.fork();
  }
} else {
  http.createServer((req, res) => {
    res.writeHead(200);
    res.end('Hello from worker ' + process.pid);
  }).listen(8000);
}

Example of spawning a child process:

const { exec } = require('child_process');

exec('ls -la', (error, stdout, stderr) => {
  if (error) {
    console.error(`Error: ${error.message}`);
    return;
  }
  if (stderr) {
    console.error(`Standard error: ${stderr}`);
    return;
  }
  console.log(`Result:
${stdout}`);
});