There's some interesting work going on at the Cambridge Computer Laboratory
on a project called Mirage which has integrated OCaml's virtual machine with
the OS in order to avoid the overhead of things like context switching
between threads:
http://www.openmirage.org/
So the OS can run async code directly without the unnecessary abstraction of
threads and thread pools.
--
Dr Jon Harrop, Flying Frog Consultancy Ltd.
http://www.ffconsultancy.com