Satu proses Node hanya menggunakan satu inti CPU (JS-nya berjalan pada satu thread). Untuk menggunakan semua inti pada mesin, Anda menjalankan berbagai proses Node — melalui modul cluster, pengelola proses seperti PM2, atau orkestrasi kontainer — dan menyeimbangkan beban permintaan di antara mereka.\n\n## Masalahnya\n\n\n\n## The cluster module — fork worker processes\n\n```js
import cluster from "cluster";
import { cpus } from "os";
import http from "http";
text A server with 8 CPU cores running ONE Node process → uses ~1 core, wastes 7. Need multiple processes to utilize all cores and handle more concurrent load. if (cluster.isPrimary) {
const numCPUs = cpus().length;
for (let i = 0; i < numCPUs; i++) {
cluster.fork(); // spawn one worker process per CPU core
}
cluster.on("exit", (worker) => {
console.log(worker ${worker.process.pid} died — restarting);
cluster.fork(); // restart a crashed worker (resilience)
});
} else {
// each worker runs the actual server; the OS load-balances connections across them
http.createServer((req, res) => res.end("handled by " + process.pid)).listen(3000);
}
\n\nProses utama melakukan fork satu worker per inti; semua worker berbagi port yang sama, dan koneksi masuk didistribusikan di antara mereka — meningkatkan throughput. Worker yang mogok dapat dimulai ulang secara otomatis untuk resilience.\n\n## Dalam praktik: gunakan PM2 (cluster mode)\n\nbash
pm2 start app.js -i max # run one instance per CPU core, with auto-restart & monitoring
\n\nAplikasi produksi biasanya menggunakan **PM2** (atau serupa) daripada menulis kode cluster secara manual — ia menangani forking, load balancing, reloads tanpa downtime, monitoring, dan restart.\n\n## Atau scaling dengan kontainer/orkestrasi\n\ntext
Run ONE Node process per container, and run MANY containers (Kubernetes, ECS),
with a load balancer in front. This is the modern cloud approach — simpler
per-process model, scaling handled by the orchestrator across machines.
\n\n## Peringatan kritis: statelessness\n\ntext
Multiple processes don't share memory. So:
⚠️ Don't store sessions/state in process memory → use Redis/a shared store
⚠️ In-memory caches aren't shared across workers → use Redis for shared cache
⚠️ WebSocket connections live on one worker → use a Redis adapter to coordinate
Perpustakaan pertanyaan wawancara IT dengan jawaban mendetail — dari Junior hingga Senior.
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