Distributed Algorithms for Multiple Entries to a Critical Section with Priority

Abstract The distributed Mutual Exclusion (M.E.) algorithms for multiple entries to a critical section (C.S.) proposed in previous publications adopt an FCFS discipline to serialize M.E. requests, i.e., the ordering of the M.E. requests is done at their virtual generation time or physical arrival time. The insertion of priority disciplines such as Short-Job-First, Head-Of-Line, Shortest-Remaining-Job-First, etc., could be useful in many applications to optimize some performance indices. A drawback is that priority disciplines are prone to starvation. This paper shows how to insert a priority-based serialization discipline in token-based M.E. algorithms for multiple entries to a C.S. avoiding starvation. Moreover, we investigate its implementation overhead in the algorithm and the number of messages per C.S. entry.