Distributing AND-work and OR-work in parallel logic programming systems

In parallel logic programming systems that exploit both AND-parallelism and OR-parallelism, the problem arises of how to distribute processors between the dynamically varying amounts of AND-work and OR-work that are available. Solutions have been reported for distributing only OR-work, or distributing only AND-work, but the issue of distributing processors between both kinds of work has not yet been addressed. In this paper, we discuss the problem of distributing AND-work and OR-work in the context of Andorra-I, a parallel logic programming system that exploits determinate AND-parallelism and OR-parallelism. We describe dynamic scheduling strategies that aim at efficiently distributing processors between AND-work and OR-work, and compare their performance with the performance produced by a static scheduling strategy, for a wide range of benchmarks.