Cluster Workers

Run one Node process per CPU core for CPU isolation and throughput.

scale

Detailed Description

A single Node process runs JavaScript on one main thread, so it cannot use all CPU cores for JS work. Cluster workers run multiple processes to use more cores.

Use cluster mode or multiple Kubernetes replicas for horizontal concurrency. Each worker needs its own memory and DB connections, so update pool sizing accordingly.

Mental Model

primary
-> fork N workers
-> each worker handles requests

When To Use

->Single process cannot use all cores
->You need process-level fault isolation
->Before scaling to multiple machines

Tools: cluster module, PM2 cluster mode, Kubernetes replicas

cluster.js

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