Comparison of optimistic and pessimistic pilgrims for concurrency management in CSCW through a probabilistic study

Abstract

Concurrency management protocols are required in CSCW applications in which users create, update and delete shared objects. Pessimistic protocols are based on lock-unlock mechanisms before writings, whereas users are allowed to do modifications without having locked the object in optimistic protocols. Our pilgrim protocol is pessimistic since a user has to become the owner of an object before modifying it optimistic protocols minimize the delays before writing. This is the reason why we defined an optimistic protocol based on the pilgrim protocol, using multiversion. After having presenting both of those protocols through a finite state automaton, we make a comparison of them based on a probabilistic study. This study allows us to choose whether the optimistic or the pessimistic pilgrim regarding user activities, types of CSCW and network.