Modified Raymond's algorithm for priority (MRA-P) based mutual exclusion in distributed systems

Abstract

The traditional approaches towards implementing mutual exclusion can not be applied for distributed systems where nodes are loosely coupled. The existing algorithms typically follow either a symmetric or a token based approach. While the symmetric algorithms tend to increase the network traffic, token based approach offers solutions at a lower communication cost. Raymond has designed an efficient token based mutual exclusion algorithm. However, one major limitation of Raymond's algorithm is the lack of fairness in the sense that a token request that is generated later may be granted ahead of another request that was made earlier. In this work, we have proposed a modification of Raymond's algorithm. The new token based algorithm not only overcomes the fairness problem, but also handles the priority of the requesting processes.