twitter/finagle

Dtab alternate not chosen over higher-precedence failing service

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#653 创建于 2017年10月4日

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 (3 评论) (0 反应) (0 负责人)Scala (8,864 star) (1,435 fork)batch import
help wanted

描述

Expected behavior

Suppose I have a dtab

  /svc => /$/namer/srv1 | /$/namer/srv2

I would expect that if every request issued to srv1 resulted in a failure, requests would start being sent to srv2 instead.

Actual behavior

So long as srv1 can be bound to an address, it receives all the traffic.

Is there any way to make it so that srv1 failures will result in requests being routed to srv2? I want srv1 to get traffic preferentially, and I don't want to rely solely on a namer's active health checks to control that.

贡献者指南

技术栈
scala
领域
backendapi
议题类型
bug
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
4
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
3-5 days
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
stale
清晰度议题是否清楚说明期望改动、验收标准和下一步。
clear
前置要求
Understanding of Finagle's Dtab routingScala basics
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
25
研究方向
Investigate how Finagle's Dtab resolution currently handles service failures. The key files are likely in com.twitter.finagle.loadbalancer and com.twitter.finagle.naming. Look at how the Balancer interface handles failed requests and whether there is existing support for failure based fallback. The issue asks for a failover mechanism when a service returns failures, which may require changes to the Dtab interpreter or load balancer configuration. Consider looking at the 'loadbalancer' package and the 'failFast' or 'retries' configuration options.