A hybrid approach to mutual exclusion for distributed systems

Abstract

A hybrid approach to mutual exclusion is proposed to minimize both message traffic and time delay at the same time. A hybrid mutual exclusion algorithm using the release local sites first mode, the requesting group semantics, and the requesting sequence 1324 (i.e., local competition followed by global competition) is found to be an efficient way to control the interaction. This hybrid algorithm uses M. Singhal's (1989) algorithm as the local algorithm and M. Maekawa's (1985) algorithm as the global algorithm. Compared to Maekawa's algorithm, which needs 3 square root N. . .5 square root N messages but two time units delay between successive executions of the critical section (where N is the number of sites in the system), the proposed hybrid algorithm can reduce message traffic by 55% and time delay by 32% at the same time. Furthermore, when a distributed system exhibits locality of requests, the proposed hybrid algorithm can achieve even better performance. >