Performance of two-phase locking schemes in distributed database systems

Abstract

Many researches on the performance analysis of two-phase locking schemes for both centralized and distributed database systems are limited in scope : some of the models for locking considered only ``static`` locking and used only exclusive locks. In this thesis, the performance of two-phase locking schemes is studied. To be this, a transaction processing model in which shared locks as well as exclusive locks can be handled is used. Static and dynamic locking schemes are simulated under the same assumptions by using the concurrent language Path Pascal. Simulation results of these two schemes are analyzed and the two schemes are compared with respect to the average response time. In general, the average response time of the static 2PL is greater than that of the dynamic 2PL under the same conditions. In addition, the rate of changes in the values of the average response time in the static 2PL is greater than that in the dynamic 2PL.