A parallel copying garbage collection algorithm for symbolic languages executing on shared-memory multiprocessors is proposed. The algorithm is an extension of Baker's sequential algorithm with a novel method of heap allocation to prevent fragmentation and facilitate load distribution during garbage collection. An implementation of the algorithm within a concurrent logic programming system, VPIM, has been evaluated and the results, for a wide selection of benchmarks, are analyzed here. We show (1) how much the algorithm reduces the contention for critical sections during garbage collection, (2) how well the load-balancing strategy works and its expected overheads, and (3) the expected speedup achieved by the algorithm.
This article appears in the IEEE Transactions on Parallel and Distributed Computing, 1993.