[Solution] Mason: Scalable, Contiguous Sequencing for Building Consistent Services

Abstract

This paper introduces a contiguous multi-sequence abstraction for building consistent, scalable services. The multi-sequence abstraction is useful when dealing with sharded datastores; the contiguity property strengthens the multi-sequence abstraction to guarantee no gaps in the sequence can be left even in the presence of failures. The outcome is an increased simplicity in developing consistent services, which is crucial for practical systems. The paper also presents MASON, a system that implements the multi-sequence abstraction and solves the scalability problem of a single monolithic sequencer. For the sake of evaluating its performance, MASON has been integrated into a distributed shared log based on CORFU, and a distributed prototype of the coordination service ZooKeeper. Overall, reviewers found the problem very relevant and timely. The presented solution is well presented, and well evaluated.