How the single threaded non blocking IO model works in Node.js

Question

I\'m not a Node programmer, but I\'m interested in how the single threaded non blocking IO model works. After I read the article understanding-the-node-js-e

Answer 1

Node.js uses libuv behind the scenes. libuv has a thread pool (of size 4 by default). Therefore Node.js does use threads to achieve concurrency.

However, your code runs on a single thread (i.e., all of the callbacks of Node.js functions will be called on the same thread, the so called loop-thread or event-loop). When people say "Node.js runs on a single thread" they are really saying "the callbacks of Node.js run on a single thread".