Adaptive Speculative Locking Protocol for Distributed Real-Time Database Systems

W. Haque and P.R. Stokes (Canada)


Distributed real-time database, concurrency control, adaptive, speculative locking.


Speculative Locking protocol (SL) is a concurrency control protocol that allows for parallel execution of conflicting transactions through a method of multilevel lending and versioning. The SL protocol shows performance improvements over the standard two-phase locking (2PL) protocol, but relies on several assumptions that would make it unsuitable in real-world scenarios. In this paper, we have proposed an adaptive speculative locking (ASL) protocol that improves performance of real-time distributed database systems by augmenting the SL protocol with four features: distributed real-time database system support; simultaneous multi-threading or page execution; control of transaction execution through transaction queue management; and restricting system memory through the use of virtual memory. The simulation results demonstrate the superiority of the ASL protocol over the SL protocols through the reduction of data contention caused by finite memory and the overall increase in transaction throughput.

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