Research on concurrency control protocol DHP-2PL for Mobile Distributed Real-Time DataBase based

The concurrency control protocol is essential for achieving high performance.This paper studies the distributed high priority two phrase locking protocol(DHP-2PL) for mobile distributed real-time databases.Two strategies are proposed to further improve the system performance:on the one hand,a dynamic priority assignment policy is adopted,which can shorten the executive time of real-time transactions and avoid the Hunger phenomenon;on the other hand,in order to increase the level of concurrency control,a hybrid locking mechanism is proposed and it can reduce the locking expense.The performance is measured and analyzed in the end of the paper.It is shown that the improvement of two methods can satisfy the deadline demands of transactions and improve the successful ratios of mobile real-time transactions.