How Does Node.js Handle Concurrency? 2023

Node.js is a single-threaded runtime environment, which means that it can only use a single CPU core at a time. However, Node.js uses an event-driven programming model and an asynchronous, non-blocking I/O API, which allows it to efficiently handle multiple concurrent connections and to perform multiple tasks simultaneously.

In Node.js, the event loop is responsible for managing and processing events, such as user input, network requests, and timer events. When an event occurs, the event loop adds the event to a queue and executes a corresponding event handler to process the event. This allows Node.js to handle multiple events concurrently and to perform multiple tasks simultaneously, without blocking the execution of the program.

For example, when a Node.js application receives a network request, the event loop will add the request to the queue and execute the appropriate event handler to process the request. While the request is being processed, the event loop can continue to handle other events and perform other tasks, such as accepting new connections or processing other requests. This allows Node.js to efficiently handle a large number of concurrent connections and to provide high levels of performance and scalability.

Overall, Node.js uses an event-driven programming model and an asynchronous, non-blocking I/O API to handle concurrency and to enable the efficient processing of multiple concurrent events and tasks. This allows Node.js to provide high levels of performance and scalability, despite being single-threaded.