The Message Passing Group Mutual Exclusion: A Review

The group mutual exclusion (GME) problem is an interesting generalization of the mutual exclusion problem. The group mutual exclusion problem deals with two contradictory issues of mutual exclusion and concurrency. The purpose is to allow concurrent access to the processes requesting for the same resource. However, the processes requesting for different resources must access requested resources in mutually exclusive way. GME is also advantageous in the scenarios, when several users share large data object stored on some secondary storage. The users, interested in currently buffered object, may access it concurrently; however, users interested in some other object (s) have to wait. Various solutions for GME problem have been proposed in the literature both for shared memory as well as message passing systems. However, a good review of the problem is still missing in the literature. In order to limit the present exposition, we could accommodate GME algorithms only for the message passing systems. Nevertheless, in addition to token-based as well as non token-based algorithms, two variants of GME problem, namely group-k mutual exclusion and extended group mutual exclusion, have also been covered.