May 2020
Beginner to intermediate
319 pages
7h 3m
Chinese
Content preview from 数据库系统内幕
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故障检测
｜
177
组中的进程定期向其他成员发送 ping 消息，以查询它们是否仍处于活动状态。如果其中
一个成员由于崩溃、网络分区或链路故障而无法响应此消息，则发出这个 ping 的成员本
身将停止响应 ping 消息。
图 9-5 展示了四个通信进程：
•
a) 初始状态：所有进程都处于活动状态并可以通信。
•
b) P
2
崩溃并停止响应 ping 消息。
•
c) P
4
检测到 P
2
的故障并停止响应自己收到的 ping 消息。
•
d) 最终，P
1
和 P
3
注意到 P
4
和 P
2
都没有响应，将进程故障传播到整个组。
a） b） c） d）
图
9-5
：
FUSE
故障检测
所有故障都通过系统从故障源传播到所有其他参与者。参与者逐渐停止响应 ping 消息，
将单个节点故障转换为组故障。
在这里，我们利用不通信作为一种传播的手段。这种方法的一个优点是保证每个成员都
能了解组的故障并对其做出充分的反应。它的一个缺点是：将单个进程与其他进程分开
的链路故障也可能会被转换为组故障，但这其实也可以被看作是一个优点，应由具体的
用例所决定。应用程序可以使用其自身对故障传播的定义来应对这种情况。
9.5
本章小结
故障检测器在任何分布式系统中都是一个重要的组成部分。正如 FLP 不可能定理所说
的，异步系统中没有协议能够保证一致性。故障检测器有助于扩展模型，允许我们通过
在准确性和完备性之间进行权衡来解决一致性问题。文献 [CHANDRA96] 描述了这一领
域的一个重要发现，证明了故障检测器是有用的，它表明，即使使用一个犯了无限多个
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
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.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.