There are systems using light-weight threads to write very high concurrency servers. That's what the Erlang VM does, for example. The GHC Haskell runtime now does this as well. They both use epoll/kqueue/etc. in their I/O systems, but the code itself is threaded in user-space, and these lightweight threads can be mapped onto a pool of OS-level threads so the programs can run on multiple cores.
Even without fancy compiler and runtime support, you can do this. In Python, you can use eventlet or gevent to write very concurrent servers with what looks like threaded code, thanks to coroutines in the interpreter. It's very pleasant.
There are systems using light-weight threads to write very high concurrency servers. That's what the Erlang VM does, for example. The GHC Haskell runtime now does this as well. They both use epoll/kqueue/etc. in their I/O systems, but the code itself is threaded in user-space, and these lightweight threads can be mapped onto a pool of OS-level threads so the programs can run on multiple cores.
Even without fancy compiler and runtime support, you can do this. In Python, you can use eventlet or gevent to write very concurrent servers with what looks like threaded code, thanks to coroutines in the interpreter. It's very pleasant.