A Hybrid Distributed Optimistic Concurrency Control Method for High—Performance Real—Time Transaction Processing

The conventional lock scheme tends to suffer from a cascade of blockings, while the optimistic concurrency control (OCC) scheme may suffer from wasting resources. To overcome these problems, some researchers have proposed a combination of OCC and lock in transaction processing. Using this method, Thomasian proposed the hybrid method for conventional distributed transaction processing, and Lam proposed the DOCC-DA protocol for distributed realtime database system based on forward validation. This paper proposes a new protocol, called Hybrid Distributed Optimistic Concurrency Control Embedded in two-Phase Commit, which is based on back validation. The new protocol makes use of access invariance and runtime information which can guarantee a rerun transaction to meet its deadline and abort the fruitless run transactions as early as possible. A series of simulation experiments have been done to investigate the performance of the new protocol. The results show that its performance is consistently better than that of other protocols.