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os.cpus()

Returns an array of objects describing each logical CPU core.

Since Node 0.3 Spec ↗

Syntax

os.cpus()

Returns

object[] — Each entry has model, speed, and times (user/sys/idle).

Examples

import { cpus } from 'node:os';

console.log(cpus().length, 'cores');
Output 
8 cores

import { cpus } from 'node:os';
import cluster from 'node:cluster';

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

Notes

Commonly used to size a worker pool or cluster. In containers `cpus().length` reports host cores, not the cgroup CPU limit; consider `os.availableParallelism()` (Node 19.4+) for that.

See also