What is clustering in Node.js, and why is it needed?
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.
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Utilize all available CPU cores instead of just one
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Improve application throughput and concurrency
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Achieve fault tolerance — if one worker crashes, others keep serving requests
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Scale the application vertically without changing application logic
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Handle more concurrent connections efficiently