What are async hooks in Node.js and how do I use them?

What are async hooks in Node.js and how do I use them?

Async hooks are a way to track asynchronous resources in Node.js. They allow you to create a context for each asynchronous operation, which can be useful for debugging and monitoring.

Can you give me an example of how to implement async hooks?

Sure! Here's a simple example:

const async_hooks = require('async_hooks');

const hook = async_hooks.createHook({
  init(asyncId, type, triggerAsyncId, resource) {
    console.log(`Init: ${asyncId} of type ${type}`);
  },
  before(asyncId) {
    console.log(`Before: ${asyncId}`);
  },
  after(asyncId) {
    console.log(`After: ${asyncId}`);
  },
  destroy(asyncId) {
    console.log(`Destroy: ${asyncId}`);
  }
});

hook.enable();

setTimeout(() => {
  console.log('Timeout executed');
}, 100);

What are the use cases for async hooks?

Async hooks can be used for various purposes, such as tracking request lifecycles, managing context in asynchronous operations, and debugging complex asynchronous code.

Are there any performance implications when using async hooks?

Yes, using async hooks can introduce some overhead, as they add additional tracking to asynchronous operations. It's important to use them judiciously.