How do I use async_hooks in Node.js?

What is async_hooks in Node.js?

async_hooks is a module in Node.js that allows you to track asynchronous resources and their lifecycle.

How can I use async_hooks to track promises?

You can use async_hooks to create a new async context when a promise is created and track its execution.

Can you show me a simple example of using async_hooks?

Sure! Here's a basic example:

const async_hooks = require('async_hooks');

const asyncHook = 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}`);
  }
});

asyncHook.enable();

const promise = new Promise((resolve) => {
  resolve('Hello, async_hooks!');
});

promise.then(console.log);

What are some common use cases for async_hooks?

Common use cases include tracking request lifecycles, debugging asynchronous code, and managing context in async operations.