Or-parallel Prolog on a distributed memory architecture

Abstract

This paper discusses the design of Dorpp, an or-parallel Prolog system for distributed memory architectures. The problem of sharing the environment across a set of nodes that do not physically share memory is addressed in a novel manner by designing a Virtual Shared Memory (VSM) scheme to specifically meet the requirements of or-parallelism. The aim is to avoid the overheads of a general VSM scheme that would provide a stricter level of memory coherence than is actually required. The paper identifies the requirements for memory coherence in or-parallel Prolog, and describes how they can be met cheaply. Simulation results are presented and analyzed in order to highlight key aspects of the system's run-time behavior.