【Author】
Choumas, Kostas; Korakis, Thanasis
【Source】IEEE TRANSACTIONS ON NETWORK AND SERVICE MANAGEMENT
【Abstract】Raft is a state-of-the-art consensus algorithm for state replication over a distributed system of nodes. According to Raft, all state updates occurring anywhere in the system are forwarded to the leader, which is elected among the system nodes to collect and replicate these updates to all other nodes. Thus, the time required for the state replication, named as system response time, depends on the delays between the leader and all other nodes. After multiple node failures and leadership transitions, each node can be leader with a probability that affects the expected response time. The leadership probabilities, in turn, are affected by the random intervals that nodes are waiting, after detecting a leader failure and before competing for the successive leadership. The Raft designers suggest the ranges of these intervals to be equal for all nodes. However, this may result in increased expected response time. In this paper, mathematical models are presented for estimating the ranges resulting in the desired leadership probabilities. The presented theoretical results are also confirmed by testbed experimentation with an open-source and widely used Raft implementation.
【Keywords】Voting; Time factors; Leadership; Delays; Heart beat; Protocols; Open source software; Raft; distributed-system; clustering; testbed-experimentation
【标题】关于在网络上使用 Raft：改进领导者选举
【摘要】Raft 是一种最先进的共识算法，用于在分布式节点系统上进行状态复制。根据 Raft 的说法，系统中任何地方发生的所有状态更新都会转发给领导者，领导者在系统节点中选举产生，以收集这些更新并将这些更新复制到所有其他节点。因此，状态复制所需的时间，称为系统响应时间，取决于领导者和所有其他节点之间的延迟。在多个节点故障和领导权转移之后，每个节点都可能成为领导者，其概率会影响预期的响应时间。反过来，领导概率受节点在检测到领导失败之后和竞争后续领导之前等待的随机间隔的影响。 Raft 设计者建议这些间隔的范围对于所有节点都是相等的。但是，这可能会导致预期响应时间增加。在本文中，提出了用于估计导致所需领导概率的范围的数学模型。所提出的理论结果也通过使用开源和广泛使用的 Raft 实现的测试平台实验得到证实。
【关键词】表决;时间因素；领导;延误；心跳;协议；开源软件;筏;分布式系统；聚类；试验台实验
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