This can be solved by minimizing blocking code, either by using actors (Erlang, Akka, etc) or just chaining callbacks on futures/promises and using monadic comp

This can be solved by minimizing blocking code, either by using actors (Erlang, Akka, etc) or just chaining callbacks on futures/promises and using monadic composition to avoid callback hell. For a concrete example, check out my Redis-based Twitter clone http://typesafe.com/activator/template/redis-twitter-clone http://typesafe.com/activator/template/redis-twitter-clone, running at https://clockwork-semaphore.herokuapp.com/# https://clockwork-semaphore.herokuapp.com/#.