Why is node.js not suitable for heavy CPU apps?

Question

Node.js servers are very efficient concerning I/O and large number of client connection. But why is node.js not suitable for heavy CPU apps in comparison to a traditional mu

Answer 1

A simple Node.js server is single-threaded, meaning that any operation that takes a long time to execute will block the rest of your program from running. Node.js apps manage to maintain a high level of concurrency by working as a series of events. When an event handler is waiting for something to happen (such as reading from the database), it tells Node to go ahead and process another event in the meantime. But since a single thread can only execute one instruction at a time, this approach can't save you from a function that needs to keep actively executing for a long time. In a multithreaded architecture, even if one function takes a long time to compute the result, other threads can still process other requests — and as long as you have a core that is not fully used at the time, there's a good chance they can do it about as quickly as if no other requests were running at all.

In order to deal with this, production Node.js apps that expect to hog a lot of CPU will usually be run in clusters. This means that instead of having several threads in one program's memory space, you run several instances of the same program under the control of one "master" instance. Each process is single-threaded, but since you have several of them, you end up gaining the benefits of multiple threads.