Exploiting Total Order Multicast in Weakly Consistent Transactional Caches

P. Ruivo, M. Couceiro, P. Romano, and L. Rodrigues.

Selected sections of this report were published in the Proceedings of the 17th Pacific Rim International Symposium on Dependable Computing (PRDC 11), Pasadena, California, USA, December 12-14, 2011.


Nowadays, distributed in-memory caches are in- creasingly used as a way to improve the performance of ap- plications that require frequent access to large amounts of data, by decoupling the persistent memory access from the critical path of the application. In order to maximize performance and scalability, these platforms typically rely on weakly consistent partial replication mechanisms. These schemes partition the data across the nodes and ensure a predefined (and typically very small) replication degree, thus maximizing the global memory capacity of the platform and ensuring that the cost to ensure replica consistency remains constant as the scale of the platform grows. Moreover, even though several of these platforms provide transactional support, they typically sacrifice consistency, ensur- ing guarantees that are weaker than classic 1-copy serializability, but that allow for more efficient implementations.

This paper proposes and evaluates two partial replication tech- niques, providing different (weak) consistency guarantees, but with in common the reliance on total order multicast primitives to serialize transactions without incurring in distributed deadlocks, a main source of inefficiency of classical two-phase commit (2PC) based replication mechanisms.

We integrate the proposed replication schemes into Infinispan, a prominent open-source distributed in-memory cache, which represents the reference clustering solution for the well-known JBoss AS platform. Our performance evaluation highlights speed- ups of up to 10x when using the proposed with respect to the native Infinispan replication mechanism, which rely on classic 2PC-based replication.

Also available extended report (pdf)

Luís Rodrigues