How Node.js Handles Multiple Requests with a Single Thread
Introduction
Hey there folks! Hope you are doing great in your life, and enjoying every bit of it, enjoyin life is also an important thing, never forget that
So, today we'll be talking about the following topics:
Single-threaded nature of Node.js
Event loop role in concurrency
Delegating tasks to background workers
Handling multiple client requests
Why Node.js scales well
Gather your focus here and bear with me till the very end of it, I promise you'll understand every bit of it!
How Node.js Handles Multiple Requests with a Single Thread
Single-Threaded Nature of NodeJS
As you know it has only a single main thread right?
Unlike other traditional servers, who create a new thread for each request, It doesn't. That's why it is more memory efficient!
Now, the question comes into the picture, how does it handles so many cuncurrent requests, despite having a single thread?
And now our whole blog will be to answer this particular question, so without wasting any further time, let's jump onto the next section!
Event Loop Role In Concurrency
What is Event Loop
Now, i am going to give you a high level idea of what event loop is, for a deeper dive you can click here.
So, basically is somewhat like a Manager for NodeJS who decided what should be done next?
The Flow of Handling Multiple Requests
It offloads the asynchronous operations to the system kernel or thread pool.
Since, it offloads the tasks, the main thread can continue to work without stopping.
When the asynchronous task gets completed, it takes the callback functions and places that in the queue to be executed by call stack.
Delegating Tasks To The Background Workers
How the Work Gets Done?
Now, have you wondered that when event loops offloads the task to the system or thread pool, what happens? Who does the job done?
This section will answer the exact same questions
Till now we only know that async operations get offloaded.
Now, the LibUV library manages 4 worker threads by deafult (you can increase or decrease but i ain't telling you how, search about it, I'm not spoon feeding here).
These worker threads are a standalone thread in themselves which does the job.
Methods of Delegation
Automatic: See, most of the async tasks automatically gets offloaded by the runtime.
Manual: For your own CPU-intensive tasks, you must manually have to delegate the work.
Now, your job is to research how to do it manually?
Why NodeJS Scales Well?
Reduced Resource Overhead: By using a single thread, Node.js avoids the significant memory consumption.
Asynchronous I/O: Whenever someone requests something that is CPU-Intensive (like DB queries, File Handling, Password Hashing, etc), NodeJS initiates the task and immediately moves to the next client. It doesn't waits for the slow operation to finish, which maximizes CPU utilisation.
Event-Driven Design: The runtime reacts to events (like a database returning data) only when they are ready. This makes it ideal for real-time applications such as chat platforms, streaming services, and IoT dashboards where small interactions happen frequently.
Lightweight Nature: Because it is built on Google's V8 engine and has a low memory footprint, Node.js is naturally suited for horizontal scaling in containerised environments like Docker and Kubernetes.
Wrap Up!
Today, we didn't just learnt about NodeJS,
We understood how it works internally right?
This is the right place where we end this blog, and congratulations, this was the last theory blog, from the next blog we'll start building backend applications using ExpressJS.
So be ready because you are coming to my domain Explaining Code
That was it for this blog, let's end it right here, Hope you enjoyed it!
I'll catch you up in the next one, until then keep coding and start enjoying life if you aren't 💝