Seonglae ChoProvides functions to track asynchronous resources
Called when a promise starts or ends, receiving an ID
AsyncLocalStorage is fine and stable
React useContext() 랑 비슷
(1) It overlays a current execution context pointer on top of the async resource graph to automatically propagate values. Rather than storing "in one place" like a global variable, it stores in a context grouped by async chain (request chain).
How does AsyncLocalStorage have a separate store for each request? Node internally creates an async resource (Timeout, Promise, FSReq, TCPWrap, etc.) whenever an asynchronous operation is created. Each resource has a unique
asyncId, and when a new resource is created, it has a triggerAsyncId indicating "who created it". In other words, asynchronous operations form a parent-child relationship graph. So when you call als.run(store, fn) at the request starting point, storage can be safely propagated to all async resources created during fn execution; there is a store that is commonly referenced by async resources created in the request chainHowever, note that ALS can break in certain cases: when the request starting point is not properly wrapped with
run(): store becomes undefined, libraries/patterns that break context propagation: (certain native N-API addons, worker thread boundaries are thread-local so they're separate) Raw async_hooks are Experimental
Async hooks | Node.js v24.10.0 Documentation
We strongly discourage the use of the async_hooks API.
Other APIs that can cover most of its use cases include:
https://nodejs.org/api/async_hooks.html
NodeJS에서 async_hooks을 이용해 요청의 고유한 context 사용하기
이 글은 Guillaume Bession의 개인 블로그에 올라와있는 Getting per-request context in NodeJS with async_hooks 글의 번역글입니다.저는 최근 NodeJS로 HTTP 서버를 개발하던 도중 문제를 맞닥트리게 되었습니다. 저는 제 코드베이스의 많은 부분에서 로깅을 하고 있었고, 각 요청별로 유니크ID를 가졌습니다. 저는 이 유니크한 ID를 각 요청 안에서 무슨 일이 일어나고 있는지
https://tech.ssut.me/getting-per-request-context-in-nodejs-with-async_hooks/
nest
Documentation | NestJS - A progressive Node.js framework
Nest is a framework for building efficient, scalable Node.js server-side applications. It uses progressive JavaScript, is built with TypeScript and combines elements of OOP (Object Oriented Programming), FP (Functional Programming), and FRP (Functional Reactive Programming).
https://docs.nestjs.com/recipes/async-local-storage
aws lambda
Node.js runtime for Lambda Managed Instances - AWS Lambda
For Node.js runtimes, Lambda Managed Instances uses worker threads with async/await-based execution to handle concurrent requests.
https://docs.aws.amazon.com/lambda/latest/dg/lambda-managed-instances-nodejs-runtime.html
