May 2020
Beginner to intermediate
319 pages
7h 3m
Chinese
Content preview from 数据库系统内幕
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184
｜
第
10
章
a
）
b
）
c
）
图
10-4
：邀请算法
与其他讨论过的算法类似，该算法允许各个进程处于多个组中，并允许多个领导者存
在。邀请算法允许创建进程组并合并它们，而不必从头开始触发新的选举，这减少了完
成选举所需的消息数量。
10.5
环算法
在环算法（ring algorithm）[CHANG79] 中，系统中所有的节点形成一个环，并且知道环
拓扑（即它们在环中的前驱和后继）。当进程检测到领导者故障时，它发起新的选举。选
举消息沿着环向下转发：每个进程联系它的后继节点（环中离它最近的下一个节点）。如
果该节点不可用，则进程跳过不可达的节点，并尝试联系环中之后的节点，直到最终有
一个节点响应为止。
节点联系其兄弟节点，沿着环收集活动节点的集合，并在将集合传递到下一个节点之前
将其自身添加到该集合中，类似于 9.1.1 节中描述的故障检测算法那样，节点在将其传
递到下一个节点之前将其标识符附加到路径中。
该算法通过完全遍历环来进行。当消息返回到开始选举的节点时，从活动节点集中选择
排名最高的节点作为领导者。在图 10-5 中，你可以看到这样一个遍历的例子：
•
a) 先前的领导者 6 发生了故障，并且每个进程都具有该环的视图。
•
b) 3 通过开始遍历来发起选举。每一步中，都维护一个在路径上遍历过的节点集合。
5 无法达到 6，所以它跳过 6 直接联系 1。
•
c) 由于 5 是排名最高的节点，3 会发起另一轮消息传递来广播关于新领导者的信息。
这种算法的变体包括收集单个排名最高的标识符，而不是一组活动节点，以节省空间 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.