Distributed Breakout vs. Distributed Stochastic: A Comparative Evaluation on Scan Scheduling

This research is motivated by an application of solving a distributed scan scheduling problem in distributed sensor networks. In this paper, we study distributed stochastic algorithm (DSA) and distributed breakout algorithm (DBA), two distributed algorithms developed earlier for distributed constraint satisfaction problems. We experimentally study their properties and compare their performance using the distributed scan scheduling problem as a benchmark. We first formulate the scheduling problem as a distributed multi-coloring problem. We then experimentally show that the solution quality and communication cost of DSA exhibit phasetransition or thrashing behavior, in that the performance degenerates abruptly and dramatically when the degree of parallel executions of distributed agents increases beyond some critical value. The results show that when controlled properly, DSA is superior to DBA, having better or competitive solution quality and significantly smaller communication cost than DBA. Therefore, DSA is the choice of algorithm for our distributed scan scheduling problem.