process/concurrency simulation

[spector@mimsy.umd.edu (Lee Spector)]

I am in search of MCL code for "process" abstractions and simulation
of concurrency. Any related code (e.g., schedulers) would also be of
interest. The only archived, relevant code of which I'm aware is Joseph
Chung's scheduler in the hyperlisp package. This provides "do x at time t"
scheduling services, while I'm more interested in "do x while doing y and z"
services. Ideal solutions would allow arbitrarily long pieces of code to
be "forked off" and run "at the same time." I'm also interested in simpler
mechanisms that assume multiple calls will be made to functions that run
quickly -- for such cases timed queue mechanisms can do the job. I've 
hacked together such a mechanism but I'm wondering if someone has developed a
solid, principled package of this sort. Any hints would also be appreciated.
 
Thanks!
 -Lee Spector (spector@cs.umd.edu)
  Department of Computer Science
  University of Maryland
  College Park, MD 20742