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arXiv · 2609.31302

KCensus: Synthesizing Latency-Optimal Consensus Fast Paths (Extended Version)

Clément Burgelin·Antoine Murat·Gal Sela·Marcos K. Aguilera·Rachid Guerraoui
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Abstract

Strongly consistent geo-replication often relies on fast paths to reduce latency in the common case of no failures or contention. Existing fast-path schemes, however, are ad hoc and restrictive: each corresponds to a point in a broad design space shaped by network topology, workload, and latency objective, so no single scheme works best across settings. This paper looks at fast-path schemes from a new perspective, as mechanisms that spread knowledge about proposals. With this view, we identify a fundamental condition on the spread of knowledge for a fast-path scheme to work. We then introduce KCensus, a framework that turns this condition into an optimization problem, synthesizing new fast-path schemes that are optimal for a given setting. We use KCensus to build a geo-replicated key-value store and evaluate it across AWS regions. Our system outperforms competing protocols, with up to 16% lower average latency.

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Clément Burgelin, Antoine Murat, Gal Sela, Marcos K. Aguilera, Rachid Guerraoui. 2026-09-28. KCensus: Synthesizing Latency-Optimal Consensus Fast Paths (Extended Version). https://doi.org/10.1145/3842654.3848528

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