Is NodeJS really single-threaded?
No! Not really! NodeJS has one main thread called event-loop and it also has a worker pool to handle blocking IO and CPU-intensive tasks. The default number of threads in the worker pool is 4, and you can change it. Node.js uses a small number of threads to handle many clients. In Node.js there are two types of threads: one Event Loop (aka the main loop, main thread, event thread, etc.), and a pool of k Workers in a Worker Pool (aka the threadpool). ...