You measure the things that block, to predict when they will queue. Your async dispatcher still takes time per request. The resources that each request needs wi

You measure the things that block, to predict when they will queue. Your async dispatcher still takes time per request. The resources that each request needs will eventually be exhausted. Your network interface isn't infinitely fast. Identify these, measure them, and you'll have a decent chance at predicting some of the problems you'll run into as things scale.