Hierarchical token based mutual exclusion algorithms

Mutual exclusion is a basic block of distributed synchronization algorithms. One of the challenges in highly distributed environments (like peer-to-peer or Grid configurations) is to provide scalable synchronizations taking into account the hierarchical network topology. This paper proposes hierarchical mutual exclusion algorithms. These algorithms are extensions of the Naimi-Trehel token algorithm, reducing the cost of latency and the number of message exchanges between far hosts. We propose three main extensions : (1) hierarchical proxy-based approach; (2) aggregation of requests; and (3) token preemption by closer hosts. We compared the performance of these algorithms on an emulated Grid testbed. We study the impact of each of the extensions, showing that the combination of them can greatly improve performance of the original algorithm.