Comment by mbid

How many systems are there that can't just spawn a thread for each task they have to work on concurrently? This has to be a system that is A) CPU or memory bound (since async doesn't make disk or network IO faster) and B) must work on ~tens of thousands of tasks concurrently, i.e. can't just queue up tasks and work on only a small number concurrently. The only meaningful example I can come up with are load balancers, embedded software and perhaps something like browsers. But e.g. an application server implementing a REST API that needs to talk to a database anyway to answer each request doesn't really qualify, since the database connection and the work the database itself does are likely much more resource intensive than the overhead of a thread.