January 2018
Beginner to intermediate
234 pages
7h 8m
Chinese
Content preview from Kafka权威指南
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32
｜
第
3
章
3.1
生产者概览
一个应用程序在很多情况下需要往
Kafka
写入消息：记录用户的活动（用于审计和分析）、
记录度量指标、保存日志消息、记录智能家电的信息、与其他应用程序进行异步通信、缓
冲即将写入到数据库的数据，等等。
多样的使用场景意味着多样的需求：是否每个消息都很重要？是否允许丢失一小部分消
息？偶尔出现重复消息是否可以接受？是否有严格的延迟和吞吐量要求？
在之前提到的信用卡事务处理系统里，消息丢失或消息重复是不允许的，可以接受的延迟
最大为
500ms
，对吞吐量要求较高——我们希望每秒钟可以处理一百万个消息。
保存网站的点击信息是另一种使用场景。在这个场景里，允许丢失少量的消息或出现少量
的消息重复，延迟可以高一些，只要不影响用户体验就行。换句话说，只要用户点击链接
后可以马上加载页面，那么我们并不介意消息要在几秒钟之后才能到达
Kafka
服务器。吞
吐量则取决于网站用户使用网站的频度。
不同的使用场景对生产者
API
的使用和配置会有直接的影响。
尽管生产者
API
使用起来很简单，但消息的发送过程还是有点复杂的。图
3-1
展示了向
Kafka
发送消息的主要步骤。
ProducerRecord
主题A
分区0
主题B
分区1
批次0
批次1
批次2
批次0
批次1
批次2
序列化器
分区器
是
是
重试？
失败？
如果成功，
返回元数据
如果不能重试，
抛出异常
图 3-1：Kafka 生产者组件图
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