Here <http://www.kegel.com/c10k.html> is an extremely interesting
article/resource list about io/thread scaling implementation.

I'm involved in a linguistic project that needs to make several
thousand concurrent connections to mine the internet for corpi. At the
moment neither ocaml lwt or heavier pthreads are capable of scaling
well enough to do this. If this problem were solved ocaml would make
an wonderful language for all kinds of massively concurrent io
interaction.

Cheers,
Julian.