Multileader WAN Paxos: Ruling the Archipelago with Fast Consensus

WPaxos is a multileader Paxos protocol that provides low-latency and high-throughput consensus across wide-area network (WAN) deployments. Unlike statically partitioned multiple Paxos deployments, WPaxos perpetually adapts to the changing access locality through object stealing. Multiple concurrent leaders coinciding in different zones steal ownership of objects from each other using phase-1 of Paxos, and then use phase-2 to commit update-requests on these objects locally until they are stolen by other leaders. To achieve zone-local phase-2 commits, WPaxos adopts the flexible quorums idea in a novel manner, and appoints phase-2 acceptors to be at the same zone as their respective leaders. The perpetual dynamic partitioning of the object-space and emphasis on zone-local commits allow WPaxos to significantly outperform leaderless approaches, such as EPaxos, while maintaining the same consistency guarantees. We implemented WPaxos and evaluated it on WAN deployments across 5 AWS regions using the benchmarks introduced in the EPaxos work. Our results show that, for a ~70% access locality workload, WPaxos achieves 2.4 times faster average request latency and 3.9 times faster median latency than EPaxos due to the reduction in WAN communication. For a ~90% access locality workload, WPaxos improves further and achieves 6 times faster average request latency and 59 times faster median latency than EPaxos.