CPU utilization of Node.js on Amazon EC2

Question

Seeing as how node is single threaded, If I have node server running on an amazon EC2 instance with 4 EC2 Compute units will it run any faster / handle more load than if I have

Answer 1

In Node.js, your code is single-threaded, but calls that e.g. access the file system or a database server do not use the main node.js thread. The main thread keeps executing while other threads are waiting for 4GB to be read from disk to RAM or for the DB server to return a response. Once the action finishes, the supplied callback is put in a queue to execute in the main thread. More or less, anyway.

The advantage being that in a server situation, you have one very fast thread that can handle thousands of concurrent requests without putting any one entirely on hold or spawning an OS thread for each client request-response cycle.

More to the point, you should benchmark your specific use case on EC2 -- multiple processors may be useful when running a single instance of node if the app does a lot of IO.