NodeJS in MultiCore System

Question 1

The JavaScript running in the Node.js V8 engine is single-threaded, but the underlying libuv multi-platform support library is multi-threaded and those threads will be distributed across the CPU cores by the operating system according to it's scheduling algorithm, so with your JavaScript application running asynchronously (and single-threaded) at the top level, you still benefit from multi-core under the covers.

As others have mentioned, the Node.js Cluster module is an excellent way to exploit multi-core for concurrency at the application (JavaScript V8) level, and since Express is cluster aware, you can have multiple worker processes executing concurrent server logic, without needing a unique listening port for each process. Impressive.

As others have mentioned, you will need Redis or equivalent to share data among the cluster worker processes. You will also want a logging facility that is cluster aware, so the cluster master and all worker processes can log to a single shared log file. The Node log4node module is a good choice here, and it works with logrotate.

Typical web examples show using the runtime detected number of cores as the number of cluster worker processes to fork, but I prefer to make that a configuration option in a config.yaml file so I can tune the number of worker processes running the main JavaScript application as needed.

Question 2

Nodejs runs in one thread, but you can start multiple nodejs processes.

If you are, for example, building web server you can route every request to one of nodejs processes.

Edit: As hereandnow78 and vkurchatkin suggested, maybe the best way to use power of multi core system would be to use nodejs cluster module

Question 3

cluster module is the solution. But u need to know that, node.js cluster is, it invokes child process. It means each process cannot share the data. To share data, u need to use Redis or other IMDG to share the data across the cluster nodes.