All 15 Clustering & Worker Threads questions
More in Clustering & Worker Threads
How does PM2's cluster mode compare to manually using Node's built-in cluster module directly in application code? How do you pass data between the main thread and a worker thread using postMessage(), and what are the limits on what can be sent? What is the difference between the 'sticky' and default load-balancing strategies when using Node's cluster module, and when does it matter? What is the difference between the number of CPU cores and the optimal number of cluster workers for a given Node.js application? How do you gracefully terminate a worker thread, and what's the difference between worker.terminate() and letting it exit naturally? What happens to in-memory state (like an in-memory cache) when using the Node.js cluster module, and how do you handle this correctly? How do you use SharedArrayBuffer to share memory directly between Node.js worker threads, and what are the safety considerations? What is a worker thread pool, and why would you build one rather than creating a new Worker for every task? How does zero-downtime restart work with Node's cluster module or PM2, and why is it important for production deployments? How do you handle an uncaught exception inside a specific cluster worker without taking down the entire application?
Advertisement
Node.js › Clustering & Worker Threads

What is the difference between spawning a Worker Thread and spawning a Child Process for running a CPU-intensive JavaScript function?

Intermediate

Answer

A Worker Thread runs within the same process, sharing the V8 binary but with its own JS heap, communicating cheaply and able to share memory via SharedArrayBuffer. A Child Process is a fully separate OS process with isolated memory, higher creation overhead, but stronger isolation -- a crash can't corrupt the parent's memory.
const worker = new Worker('./cpu-task.js'); // lighter weight, shared process
const child = fork('./cpu-task.js'); // heavier, fully isolated process
Real-world example A sandbox running untrusted user-submitted JavaScript deliberately uses child_process.fork() with resource limits rather than a worker thread, since stronger process isolation prevents a malicious snippet from corrupting the parent's memory.

Common follow-ups: In what scenario is the stronger isolation of a child process worth the higher overhead?;How does IPC between a parent and forked child compare to postMessage() between worker threads?

Child Processes & Process Management;Security
All 15 Clustering & Worker Threads questions