Blocking And Non-Blocking IO in Node Js

Understanding blocking and non-blocking IO in Node Js is important for creating efficient and responsive applications. However, Node js works on the non-blocking I/O model. In this blog post, we will explain what blocking and non-blocking IO in Node Js mean, how they impact Node Js applications, and when to use each approach.

What is Blocking I/O?

As the name suggests, blocking means the execution of one operation block until the current operation is finished. Such operations take place synchronously means they take place in a step-by-step procedure. Let us explain to you in a more general way with real-life examples. Suppose you are standing in a line to order food, you have to stand there until your turn comes to order, and while you’re waiting, you cannot do anything. Similarly in Node js the blocking I/O occurs when the program has to wait for resources like reading files from disks or making network requests.

The drawback of Node js is that it can cause inefficiencies, especially in operations applications that require a high level of synchrony. 

What is Non-Blocking I/O?

Non-blocking I/O in contrast allows other codes to execute while waiting for I/O operations to complete. It does not block the execution of further operations. These operations are executed synchronously means that programs do not necessarily have to execute line by line. Connecting it with our food ordering example, it’s like placing your order at a self-service kiosk and then mingling with other activities while your food is being prepared. 

In Node.js, non-blocking I/O allows programs to function in multiple I/O operations without waiting for each one to finish before moving on to the next task. It is also beneficial as it improves the responsiveness and efficiency of the application specifically when there is a requirement of high concurrency or real-time. By allowing the program to handle multiple tasks simultaneously, non-blocking I/O can significantly enhance the performance of Node.js applications.

Choosing Between Blocking And Non-Blocking I/O

Wondering when you should opt for blocking versus non-blocking I/O in your Node.js applications? The choice depends on the specific requirements of your project.

You can go for Blocking I/O for simple scripts or applications where performance is not a critical concern. Whereas, if responsiveness and scalability are your concern then non-blocking I/O is the preferred approach. By utilizing asynchronous operations and event-driven architecture, non-blocking I/O enables Node.js applications to tackle large amounts of simultaneous requests efficiently.

You should carefully choose between blocking and non-blocking I/O when designing your Node.js applications. Blocking I/O may be simpler to implement initially, non-blocking I/O means superior performance and scalability, especially in modern web and microservices architecture.


Wrapping up, it’s important to understand the concept of blocking and non-blocking I/O for developing high-performance Node.js applications. You can optimize the responsiveness and scalability of your applications by selecting the appropriate approach based on your requirements. You must master these concepts to utilize the potential of Node.js, no matter if you’re building a simple script or a complex web applications