The Efficacy of Commutativity-Based Semantic Locking in a Real-World Application

While the dominant approach to persistent storage in practice is to use a relational DBMS, there are some specialist applications that rely on object stores. The performance of these applications depends on the efficiency of the object store´s concurrency control mechanism. Today´s predominant concurrency control mechanism is strict two-phase object locking. In the 1980s, an interesting alternative was developed: commutativity-based semantic locking. In theory, it can outperform traditional locking schemes in certain scenarios with appropriate commutativity potential. In this paper, we study the real-world performance of different locking strategies in a particular industrial application from the telecommunications sector. We compare object-based locking and commutativity-based semantic locking. We found that, in this application, semantic locking performs equally to, but no better than, object locking in reasonable mixes of real- world transactions, and that it only outperforms in a deliberately contrived mix.