How many threads?

I am about to do some multithreading code to get some parallelism when
waiting for Internet links to respond. The question comes How many
threads? Well it depend on too many things. How much ram, how fast the
connections, what else is going on in the machine.

The optimal choice could change over time, even within a single run.

What I need is some sort of homing mechanism that homes in on the
optimal number. Surely this is a common problem. Are there classes to
handle this automatically?
--

Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com
.