arXiv subjects

Reginald Frank

Publications and source records attributed to Reginald Frank.

3 recordsLinked to original sources

arXiv2026

Real Life Is Uncertain. Consensus Should Be Too!

Modern distributed systems rely on consensus protocols to build a fault-tolerant-core upon which they can build applications. Consensus protocols are correct under a specific failure model, where up to $f$ machines can fail. We argue that this $f$-threshold failure model oversimplifies the real world and limits potential opportunities to optimize for cost or performance. We argue instead for a probabilistic failure model that captures the complex and nuanced nature of faults observed in practice. Probabilistic consensus protocols can explicitly leverage individual machine \textit{failure curves} and explore side-stepping traditional bottlenecks such as majority quorum intersection, enabling systems that are more reliable, efficient, cost-effective, and sustainable.

cs.DC↗

arXiv2023

Picsou: Enabling Replicated State Machines to Communicate Efficiently

Replicated state machines (RSMs) cannot communicate effectively today as there is no formal framework or efficient protocol to do so. To address this issue, we introduce a new primitive, Cross-Cluster Consistent Broadcast (C3B) and present PICSOU, a practical implementation of the C3B primitive. PICSOU draws inspiration from networking and TCP to allow two RSMs to communicate with constant metadata overhead in the failure-free case and a minimal number of message resends in the case of failures. PICSOU is flexible and allows both crash fault tolerant and Byzantine fault tolerant consensus protocols to communicate. At the heart of PICSOU's good performance and generality is the concept of QUACKs (quorum acknowledgments). QUACKs allow nodes in each RSM to precisely determine when messages have definitely been received, or likely lost. Our results are promising: we obtain up to 24x better performance than prior solutions on microbenchmarks and applications, ranging from disaster recovery to data reconciliation.

cs.DC↗

arXiv2018

A Tight Lower Bound for Clock Synchronization in Odd-Ary M-Toroids

Synchronizing clocks in a distributed system in which processes communicate through messages with uncertain delays is subject to inherent errors. Prior work has shown upper and lower bounds on the best synchronization achievable in a variety of network topologies and assumptions about the uncertainty on the message delays. However, until now there has not been a tight closed-form expression for the optimal synchronization in $k$-ary $m$-cubes with wraparound, where $k$ is odd. In this paper, we prove a lower bound of $\frac{1}{4}um\left(k-\frac{1}{k}\right)$, where $k$ is the (odd) number of processes in the each of the $m$ dimensions, and $u$ is the uncertainty in delay on every link. Our lower bound matches the previously known upper bound.

cs.DC↗