RACE: A Concurrency Control Protocol for Time-Constrained Transactions

Abstract

The two-phase locking with high priority (2PL-HP) protocol is a broadly used concurrency control protocol as it better handles the priority inversion problem. However, its performance might get degraded due to the inclusion of cyclic restart, deadlock, unnecessary abort, pseudo-priority inversion, and starvation. To overcome the above problems, this paper proposes a Reduction of long transactions starvation effect, Avoidance of deadlock and pseudo-priority inversion, and Conditional-restart for an Efficient resource utilization (RACE) concurrency control protocol. The RACE specifically aims at reducing the transaction miss percent by eliminating the following problems—deadlock through dividing the execution stage in the locking phase and processing phase, the cyclic restart through prejudging its occurrence, and the pseudo-priority inversion that may occur with an intermediate lock holder low priority cohort. Moreover, it reduces unnecessary transaction aborts through the utilization of the priority inheritance method and saves long transactions from being starved to some extent by ensuring fair chances of their completion. Simulation results confirm up to 11% improvement in transactions miss percent and up to 38% reduction in transactions’ rollbacks in RACE protocol over 2PL-HP and extended 2PL-HP.