面向基于领导者的共识数据存储的操作类型感知客户端路由
Operation-Type-Aware Client Routing for Leader-Based Consensus Datastores
- Amazon Web Services（亚马逊云服务）
- NVIDIA（英伟达）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
针对基于领导者的共识数据存储，提出操作感知客户端路由策略，将写操作固定至领导者、读操作分发至健康读池，可显著降低延迟并提升吞吐量，且在etcd与ZooKeeper上均有效。
AI中文摘要：
基于领导者的共识数据存储（如etcd、ZooKeeper）面临两个相互竞争的路由目标：在集群成员间均匀分散负载，以及将操作路由至协议角色与操作匹配的成员。写操作必须通过领导者提交，因此将其发送至其他成员会增加一次转发跳数；线性一致性读操作仅需轻量级领导者确认，即可由任意成员本地处理。当前etcd客户端使用gRPC的round_robin负载均衡器，在集群成员间均匀分发读操作与写操作。操作感知客户端通过将写操作固定至领导者、将读操作分发至健康读池来解决该问题。在3节点etcd集群的稳态下（读/写比例为80/20，共5次试验），该方法将写操作的P50延迟降低29%，吞吐量提升9%；当某个跟随者发生静默降级时，操作感知客户端可检测到延迟变化并将其从读池中移除，进而将读操作的P99延迟降低64%、写操作的P99延迟降低74%，吞吐量提升89%。将相同路由规则应用于ZooKeeper（ZAB协议，不同实现）也得到一致结果，表明该结果源于基于领导者的共识结构，而非单个系统的实现细节。自适应发现该策略的关键障碍在于，领导者确认的往返发生在集群成员之间，因此客户端仅能观测到混合延迟信号，无法直接获取决定性的协调开销。
英文摘要：
Leader-based consensus datastores (etcd, ZooKeeper) face two competing routing goals: spread load evenly across members, and route operations to the member whose protocol role matches the operation. Writes must commit through the leader, so sending them elsewhere adds a forwarding hop. Linearizable reads need only a lightweight leader confirmation before any member can serve them locally. The upstream etcd client uses gRPC's round_robin balancer, distributing reads and writes uniformly across cluster members. An operation-aware client resolves this by pinning writes to the leader and distributing reads across the healthy read pool. In steady state on a 3-node etcd cluster (80/20 read/write mix, 5 trials), this lowers write P50 by 29% and raises throughput by 9%. When a follower degrades silently, the operation-aware client detects the latency shift and removes it from the read pool, cutting read P99 by 64%, write P99 by 74%, and raising throughput by 89%. The same routing rule applied to ZooKeeper (ZAB protocol, different implementation) points in the same direction, showing that the result follows from leader-based consensus structure rather than one system's implementation. The key obstacle to discovering this policy adaptively is that the leader confirmation round-trip occurs between cluster members, so the client sees only a blended latency signal rather than the decisive coordination cost directly.
