# Using NodeJS's AsyncLocalStorage to Instrument a Webserver In the dark times before [`AsyncLocalStorage`](https://nodejs.org/api/async_context.html#class-asynclocalstorage), it could be hard to tell why a request to a server would occasionally time out. Were there multiple relatively slow queries somewhere in that route's code? Was another request on the same container saturating a database connection pool? Did another request block the event loop? It was possible to use tracing, profiling,...
