TIP: As an asynchronous event-driven JavaScript runtime, Node.js is designed to build scalable network applications.
Almost no function in Node.js directly performs I/O, so the process never blocks. Thanks to this, scalable systems is very reasonable to be developed in Node.js.
https://nodejs.org/en/docs/guides/blocking-vs-non-blocking/[Overview of Blocking vs Non-Blocking^]
TIP: *Node.js* is similar in design to, and influenced by, systems like *Ruby's Event Machine* and *Python's Twisted.*
Node.js takes the event model a bit further. It presents an *event loop as a runtime construct* instead of a library.
*In other systems, there is always a blocking call to start the event-loop.*
Typically,
- behavior is defined through callbacks at the beginning of a script,
- and at the end a server is started through a blocking call like *EventMachine::run().*
[NOTE]
====
In Node.js, there is no such start-the-event-loop call.
- *Node.js* simply *enters the event loop after executing the input script.*
- *Node.js exits the event loop* when there are *no more callbacks to perform.*
Node.js being *designed without threads* doesn't mean you can't take advantage of multiple cores in your environment.
Child processes can be spawned by using our *child_process.fork() API,* and are designed to be easy to communicate with.
TIP: Built upon that same interface is the cluster module, which *allows you to share sockets between processes* to enable load balancing over your cores.
