Distributed mutual exclusion algorithms

Abstract

In this thesis we present three original algorithms which solve the distributed mutual exclusion problem. Two of the three solve the problem of allowing only one site at a time into the critical section. The third solves the more difficult problem of allowing a specific number of sites (k sites) into the critical section at a time; All three algorithms are Token Based . That is, they make use of a token and token queue in order to guarantee mutual exclusion. Only the site that currently has the token is allowed to enter its critical section in the 1 mutual exclusion algorithms. Only the sites that have seen the token, since they requested it, are allowed to enter their critical sections in the k mutual exclusion algorithm; The primary goal of our algorithms is efficiency. Both of our 1 mutual exclusion algorithms require between 2 and n messages per critical section (n being the number of sites) depending on the number of requests for the critical section. Our k mutual exclusion has similar requirements between 3 and n messages per critical section depending on the number of requests for the critical section. (Abstract shortened by UMI.)