C.A.R. Hoare's book Communicating Sequential Processes (CSP) should be useful. Also, Russ Cox (the principal author of the C code this library is based upon) has a brief history of this approach to threading, which might be informative.
The package is layered on top of Bordeaux-Threads for portability. It has had at least rudimentary testing under SBCL, Lispworks, openMCL, ECL and Allegro. Documentation and a couple of examples are included with the package.
Download ASDF package from http://www.staff.ncl.ac.uk/roger.peppe/csp.tgz
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