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arXiv · 2110.00960

Be Aware of Your Leaders

Shir Cohen·Rati Gelashvili·Lefteris Kokoris Kogias·Zekun Li·Dahlia Malkhi·Alberto Sonnino·Alexander Spiegelman
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Abstract

Advances in blockchains have influenced the State-Machine-Replication (SMR) world and many state-of-the-art blockchain-SMR solutions are based on two pillars: Chaining and Leader-rotation. A predetermined round-robin mechanism used for Leader-rotation, however, has an undesirable behavior: crashed parties become designated leaders infinitely often, slowing down overall system performance. In this paper, we provide a new Leader-Aware SMR framework that, among other desirable properties, formalizes a Leader-utilization requirement that bounds the number of rounds whose leaders are faulty in crash-only executions. We introduce Carousel, a novel, reputation-based Leader-rotation solution to achieve Leader-Aware SMR. The challenge in adaptive Leader-rotation is that it cannot rely on consensus to determine a leader, since consensus itself needs a leader. Carousel uses the available on-chain information to determine a leader locally and achieves Liveness despite this difficulty. A HotStuff implementation fitted with Carousel demonstrates drastic performance improvements: it increases throughput over 2x in faultless settings and provided a 20x throughput increase and 5x latency reduction in the presence of faults.

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Shir Cohen, Rati Gelashvili, Lefteris Kokoris Kogias, Zekun Li, Dahlia Malkhi, Alberto Sonnino, Alexander Spiegelman. 2021-10-03. Be Aware of Your Leaders. https://arxiv.org/abs/2110.00960

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