SpotLess: Concurrent Rotational Consensus Made Practical through Rapid View Synchronization

The emergence of blockchain technology has renewed the interest in consensus-based data management systems that are resilient to failures. To maximize the throughput of these systems, we have recently seen several prototype consensus solutions that optimize for throughput at the expense of overall implementation complexity, high costs, and reliability. Due to this, it remains unclear how these prototypes will perform in real-world environments. In this paper, we present SpotLess, a novel concurrent rotational consensus protocol made practical. Central to SpotLess is the combination of (1) a chained consensus design for replicating requests with a reduced message cost; (2) the novel Rapid View Synchronization protocol that enables robust and continuous low-cost failure recovery that eliminates the traditional complex, error-prone view-change protocol; and (3) a high-performance concurrent consensus architecture in which independent instances of the chained consensus operate concurrently to process requests with high throughput and without single-replica bottlenecks. Due to the concurrent consensus architecture, SpotLess greatly outperforms traditional primary-backup consensus protocols such as PBFT (by up to 430%), Narwhal-HS (by up to 137%), and HotStuff (by up to 3803%). Due to its reduced message cost, SpotLess is even able to outperform RCC, a state-of-the-art high-throughput concurrent consensus protocol, by up to 23%. Furthermore, SpotLess is able to maintain a stable and low latency and consistently high throughput even during failures.