Clustering & Worker Threads

// Cluster & Worker Threads
// Cluster — multiple processes
import cluster from 'cluster';
import os from 'os';

if (cluster.isPrimary) {
  const cpus = os.cpus().length;
  console.log(`Primary ${process.pid} forking ${cpus} workers`);
  for (let i = 0; i < cpus; i++) cluster.fork();
  cluster.on('exit', (worker) => {
    console.log(`Worker ${worker.process.pid} died, restarting...`);
    cluster.fork(); // auto-restart
  });
} else {
  // Each worker runs the server
  import('./server').then(m => m.start());
}

// Worker Threads — for CPU-intensive in same process
import { Worker, parentPort, workerData } from 'worker_threads';

function runHeavyTask(data: number[]): Promise<number> {
  return new Promise((resolve, reject) => {
    const worker = new Worker('./worker.ts', { workerData: data });
    worker.on('message', resolve);
    worker.on('error', reject);
  });
}

// worker.ts
const data = workerData as number[];
const result = data.reduce((a, b) => a + b, 0);
parentPort?.postMessage(result);

// File System Operations
import { readFile, writeFile, mkdir, readdir, stat } from 'fs/promises';
import { existsSync } from 'fs';
import path from 'path';

// Read & write
const data = await readFile('config.json', 'utf-8');
const config = JSON.parse(data);

await writeFile('output.json', JSON.stringify(config, null, 2));

// Directory operations
await mkdir('dist/assets', { recursive: true });
const files = await readdir('./src', { withFileTypes: true });
const tsFiles = files.filter(f => f.isFile() && f.name.endsWith('.ts'));

// File info
const info = await stat('package.json');
console.log(info.size, info.mtime);

// Path utilities
path.join('/Users', 'project', 'src');   // OS-specific separators
path.resolve('./src', '../dist');         // absolute path
path.extname('file.ts');                  // '.ts'
path.basename('/a/b/file.ts', '.ts');     // 'file'