What are some use cases for async hooks in Node.js?

What are some use cases for async hooks in Node.js?

Async hooks in Node.js are useful for tracking asynchronous resources. Common use cases include monitoring request lifecycles, managing context for logging, and debugging asynchronous code.

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

Sure! You can create an async hook using the 'async_hooks' module. 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();

This will log the lifecycle of async operations.

What are the performance implications of using async hooks?

Using async hooks can introduce some overhead, as they track the lifecycle of asynchronous operations. However, the impact is generally minimal unless you're handling a very high volume of async operations.

Are there any libraries that simplify working with async hooks?

Yes, libraries like 'cls-hooked' and 'async-local-storage' provide a simpler API for managing context in asynchronous code, making it easier to work with async hooks.