What should I learn first about Node.js threading?
That JavaScript runs on a single main thread. The event loop processes callbacks here. Blocking the main thread is the biggest performance issue. This is the foundation for understanding everything else about threading in Node.js.
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More FAQs in A Roadmap to Understanding Threading in Node.js
In order: the single main thread, non-blocking I/O and the event loop, the libuv thread pool, CPU-bound vs I/O-bound work, worker threads, and tuning and monitoring. Each step builds real understanding of how Node.js handles concurrency.
After understanding non-blocking I/O and the event loop. The thread pool handles operations that cannot be done async by the OS, so it builds on your understanding of async I/O. Learn UV_THREADPOOL_SIZE and which operations use the pool.
After understanding CPU-bound vs I/O-bound work. Worker threads are for CPU-heavy computation that would block the main thread, so understanding the difference between CPU and I/O work comes first.
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