A dynamic token-based distributed mutual exclusion algorithm

The authors present a dynamic token-based mutual exclusion algorithm for distributed systems. In the algorithm, a site invoking mutual exclusion sends token request messages to a set of sites possibly holding the token as opposed to all the sites as in the algorithm proposed by I. Suzuki and T. Kasami (1985). A request set is used to record the identifiers of such a set of sites in the system. The algorithm is dynamic because the request set is dynamically changed as the algorithm is executed. As the size of the request set is reduced, the number of the messages exchanged per critical section (CS) execution is reduced. Compared with Suzuki and Kasami's algorithm, the proposed algorithm can reduce the number of the messages exchanged by 40% when the traffic is light. Finally, the authors discuss relationship between the token-based and non-token-based mutual exclusion algorithms. This relationship motivated the authors to design such a dynamic token-based algorithm.>