University of Utah
			Department of Computer Science
				       
				 UUCS-92-011
				       
				       
				       
		  A Distributed Garbage Collection Algorithm
				       
			      Terence Critchlow
				       
				   Abstract
				       

Concurrent Scheme extends the Scheme programming language, providing parallel
program execution on a distributed network.  The Concurrent Scheme environment
requires a garbage collector to reclaim global objects; objects that exist in
a portion of the global heap located on the node that created them.  Because a
global object may be referenced by several nodes, traditional garbage
collection algorithms cannot be used.  The garbage collector used must be able
to reclaim global objects with minimal disturbance to the user program, and
without the use of global state information.  It must operate asynchronously,
have a low network overhead, and be able to handle out-of-order messages.
This thesis describes a distributed reference counting garbage collector
appropriate for the reclamation of global objects in the Concurrent Scheme
environment.