Node.js, by design, is single-threaded. This means it processes one task at a time in its main event loop. So what happens when you want to handle CPU-intensive tasks like video processing or heavy computations without blocking the entire application? This is where child processes come in — and to make it easy, let’s explain it using a toddler analogy.
Imagine a Toddler and Their Toys
Think of Node.js as a toddler playing with a single toy at a time. They are focused — pick up a toy, play with it, and only then move to the next. That’s single-threaded behavior.
Now imagine someone asks the toddler to also solve a big puzzle. If the toddler starts working on it alone, they’ll stop playing with their other toys until it’s done. This is similar to how Node.js blocks the event loop during a heavy task.
Bringing in the Siblings – The Child Processes
Instead of stopping everything, the toddler (Node.js) can call in siblings (child processes) to help. Each sibling can take on a heavy task like solving the puzzle while the toddler continues playing. These siblings work independently but still stay in touch. That’s how child processes work in Node.js — they are separate instances that can handle work without blocking the main thread.
Technical View
Node.js provides a built-in child_process module. Using methods like fork(), exec(), or spawn(), developers can create child processes that run alongside the main process, communicating through events and messages.
const { fork } = require('child_process');
const child = fork('heavyTask.js');
child.on('message', (msg) => {
console.log('Message from child:', msg);
});
child.send({ task: 'start' });Summary
When Node.js (the toddler) can't multitask due to its single-threaded nature, it brings in child processes (siblings) to help with big tasks. This allows the toddler to keep playing while others take care of the heavy lifting — all without chaos.
Would you like a visual diagram of this toddler analogy?