Study of an optimistic protocol for concurrency management in CSCW

Users need to access to shared objects concurrently in CSCW applications. Concurrency management protocols have been designed in order to maintain the consistency. Those protocols are either optimistic or pessimistic, like our own protocol called Pilgrim. This protocol is based on ownership and lock-unlock mechanisms. In order to minimize the delay before writing, we defined an optimistic protocol based on mechanisms such as atomization and multiversion. This paper presents both of those protocols through a finite state automaton, and we compare them computing the probabilities to be able to modify a shared object using the pessimistic version on the one hand, and the optimistic one on the other hand. Finally, we propose an accurate study of parameters that permits to choose one of the both protocols studied.