SIMULATING CONCURRENCY CONTROL WITH DEADLOCK AVOIDANCE IN REAL-TIME TRANSACTION PROCESSING

摘要

The correctness of real-time database systems depends on both the data consistency and the timeliness of the results. We present a very comprehensive study which demonstrates the effect of using various priority assignment and concurrency control protocols with a variety of underlying system configurations, including use of multiple disks, CPUs, and buffer sizes. The study identifies various bottlenecks and solutions under varying system loads and transaction parameters. Both preemptive and non-preemptive protocols are studied under realistic assumptions. Finally, a performance comparison of such a system operating under deadlock and no-deadlock conditions provides insight into the potential waste of resources when concurrency is restricted.