C10K is a coroutine-based alternative implementation of the posix thread. It allows existing non-asynchronous programs, regardless of the programming language they use, to become coroutine-based asynchronous programs without any modifications, and makes it possible for programs to handle a large number of clients at the same time.
At this moment C10K is still under heavy development.
The c10k command can start a specified program that runs asynchronously.
$ c10k ab -c 1000 -n 10000 http://example.com/$ c10k bash