Message-efficient distributed mutual exclusion incorporating the `least recently used' fairness criterion

The fairness criterion is a crucial attribute of distributed mutual exclusion algorithms. This criterion determines for how long a node, which has issued a request for executing a critical section, has to wait. All solutions to the distributed mutual exclusion problem are expected to be starvation free. Ensuring starvation freedom alone may not be sufficient in large distributed systems with online users. The least recently used (LRU) criterion is better suited for such systems. In this note, the authors have presented a distributed mutual exclusion algorithm incorporating the LRU fairness criterion. The algorithm is an improvement on Raymond's tree based algorithm for distributed mutual exclusion. The message complexity of the algorithm is low despite incorporating such a strong fairness criterion.