Speeding up Consensus by Chasing Fast Decisions

TL;DR

Caesar is a new multi-leader consensus protocol that improves performance in geo-replicated systems by allowing fast decisions even with conflicting requests, outperforming existing protocols under high conflict scenarios.

Contribution

It introduces a novel ordering protocol that enables fast decisions without rejection in multi-leader consensus, enhancing performance during conflicting workloads.

Findings

Caesar outperforms EPaxos by up to 1.7x with 30% conflicts.

Caesar outperforms Multi-Paxos by up to 3.5x.

Demonstrated effectiveness on Amazon EC2 with 5 geo sites.

Abstract

This paper proposes Caesar, a novel multi-leader Generalized Consensus protocol for geographically replicated sites. The main goal of Caesar is to overcome one of the major limitations of existing approaches, which is the significant performance degradation when application workload produces conflicting requests. Caesar does that by changing the way a fast decision is taken: its ordering protocol does not reject a fast decision for a client request if a quorum of nodes reply with different dependency sets for that request. The effectiveness of Caesar is demonstrated through an evaluation study performed on Amazon's EC2 infrastructure using 5 geo-replicated sites. Caesar outperforms other multi-leader (e.g., EPaxos) competitors by as much as 1.7x in the presence of 30% conflicting requests, and single-leader (e.g., Multi-Paxos) by up to 3.5x.