Queueing Analysis of Global Locking Synchronization Schemes for Multicopy Databases

Locking is a simple scheme to synchronize multiple updates in a multicopy distributed database system. Various schemes were proposed before to maintain the consistency of the distributed database. But these schemes were compared to each other mostly on heuristic base. In this paper, three analytic queueing models for the Network Semaphore scheme, Hopping Permit scheme, and Adaptive Hopping Permit scheme are developed. Incorporating special waiting stages allows the latter two control schemes to he modeled as M/G/1 queueing systems. Shown in this paper are various performance measures of the models, which can provide much insight into these schemes. The validity of these models is verified by the simulation results.