Node.js runs on a single thread, meaning it can only utilize one CPU core at a time. Clustering solves this by spawning multiple worker processes, each running on its own core, enabling true parallelism and better resource utilization.
Node.js is single-threaded by design, which means a standard Node.js application can only use one CPU core regardless of how many cores the server has. This becomes a bottleneck under heavy load. The Cluster module allows you to create child processes (workers) that all share the same server port, effectively distributing the workload across all available CPU cores.
Utilize all available CPU cores instead of just one
Improve application throughput and concurrency
Achieve fault tolerance — if one worker crashes, others keep serving requests
Scale the application vertically without changing application logic
Handle more concurrent connections efficiently