Clustering spawns multiple OS-level processes ideal for I/O-bound tasks like HTTP servers, while Worker Threads run multiple threads within a single process, sharing memory, and are ideal for CPU-bound tasks like data processing or computation.
Both Clustering and Worker Threads allow Node.js to use multiple CPU cores, but they work at different levels and solve different problems. Clustering is best for scaling network servers, while Worker Threads are best for parallelizing heavy computations without spawning expensive OS processes.
Each worker is a separate OS process — higher memory overhead per worker
No shared memory — complete isolation between processes
Ideal for HTTP servers, API services, and I/O-bound workloads
Communication via IPC with JSON message serialization
A process crash is isolated — one worker dying does not affect others
Available since Node.js v0.8
Threads within the same process — lower memory overhead
Can share memory via SharedArrayBuffer and Atomics
Ideal for CPU-intensive tasks: image processing, cryptography, ML inference
Communication via MessageChannel or postMessage
Thread crash can potentially affect the entire process
Available since Node.js v10.5 (stable in v12)