A reasonable compromise is to use a threadpool (which is a big part of what comes with wangle) with a fixed number of threads and you queue the tasks to be run

A reasonable compromise is to use a threadpool (which is a big part of what comes with wangle) with a fixed number of threads and you queue the tasks to be run by the threads. It works quite well in practice, and you can use coroutines (I'm most familiar with the implementation in boost coroutine and the Ewan webserver personally) to go the whole hog and get something as lightweight as Erlang green threads or goroutines. I would only bother doing that of course if in your particular use case you find the threadpool doesn't perform well. With proper sizing and broken up units of work, it really works quite well in practice.