What is the thread pool in Node.js?
A pool of 4 threads (by default) in libuv that handles operations that cannot be done asynchronously, like file system operations and some crypto work. The thread pool runs blocking work off the main thread.
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More FAQs in Node.js Architecture Explained: V8, libuv, and the Event Loop
V8 runs JavaScript, libuv handles async I/O, the event loop processes callbacks on a single thread, and the thread pool handles blocking work like file system operations. Understanding how these fit is key to writing efficient Node.js code.
libuv is a C library that provides async I/O for Node.js. It handles file system operations, network operations, and the event loop. Without libuv, Node.js would not be non-blocking.
JavaScript runs on a single thread in Node.js, so one blocking operation stops all requests. However, libuv uses a thread pool for blocking work like file system operations, so those run off the main thread.
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