Scalable predictive concurrency control for large distributed virtual environments with densely populated objects.

ABSTRACTWe propose an enhanced prediction-based concurrency control scheme that supports the scalability of concurrency control for large distributed virtual environments especially where entities are highly populated and tend to gather closely. The prediction scheme is based on an entity-centric multicast group. Only the users surrounding a target entity multicast the ownership requests via an entity multicast group and become owner candidates. The current owner predicts the next owner among the owner candidates and sends an ownership to the next owner in advance. However, if entities are assigned their own multicast address when they are close to each other, users have to continuously issue join messages as moving by the entities. To reduce the network and message exchange overhead, we use the location proximity of entities in virtual environments. By grouping closely gathered entities into one entity group and sharing a multicast address among group member entities, we reduce the number of frequent join and leave operations and join messages, therefore maintain enough interactive performance. The experiment results show that the proposed mechanism improves scalability especially when entities are closely gathered.