A tree-based algorithm for distributed mutual exclusion

Reviewer: Charles N. Schroeder

This interesting and well-written paper presents an algorithm for distributed mutual exclusion in a computer network. The algorithm uses messages, rather than shared memory, to pass the equivalent of a token that allows the node holding the privilege to enter the critical section. The author compares the algorithm to others, suggests ways to improve it, and lists some possible problems. The network topology affects the algorithm's performance (the number of messages passed); Raymond discusses best and worst cases as well as two variations of the algorithm's implementation. I found the paper easy to read and to follow. One could easily scan it for the major concepts, and even a novice at distributed systems and networking should be able to follow the flow of the paper and most of the proofs. I recommend this interesting approach to the general reader interested in distributed systems and networks.