Context-Aware Tracking with AsyncLocalStorage

Snippet

Context-Aware Tracking with AsyncLocalStorage

AsyncLocalStorage allows persisting data across asynchronous boundaries without manual prop drilling. It is essential for tracking request-specific metadata (like correlation IDs) in complex Node.js microservices.

snippet.js
javascript
const { AsyncLocalStorage } = require('node:async_hooks');
const storage = new AsyncLocalStorage();
 
function logWithId(msg) {
  const id = storage.getStore()?.requestId || 'anonymous';
  console.log(`[${id}] ${msg}`);
}
 
function handleRequest(reqId) {
  storage.run({ requestId: reqId }, () => {
    setImmediate(() => logWithId('Processing complete'));
  });
}
 
handleRequest('req-123');

nodejs

Breakdown

const storage = new AsyncLocalStorage();

Initializes a new storage instance to hold asynchronous context.

storage.getStore()?.requestId

Safely retrieves the current context from the async execution chain.

storage.run({ requestId: reqId }, () => { ... });

Executes a callback within a scoped context that persists through nested async calls.

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Context-Aware Tracking with AsyncLocalStorage

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