November 2022
Beginner to intermediate
346 pages
11h
Chinese
Content preview from Kafka权威指南（第2版）
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302
｜
第
14
章
除了单元测试，还需要进行集成测试。对
Streams
来说，有两个流行的集成测试框架：
EmbeddedKafkaCluster
和
Testcontainers
。前者的
broker
和测试代码运行在同一个
JVM
中，
后者的
broker
运行
Docker
容器中
（还有其他需要用到的组件）。建议使用
Testcontainer
，
因为它使用了
Docker
，
可以将
Kafka
、依赖项和要用到的资源与要测试的应用程序完全隔
离开。
以上这些只是对
Streams
测试方法的一个简单概述
。如果想更深入地了解拓扑测试，并获
得更详细的代码示例，那么建议阅读“
T
esting Kafka Streams
—
A Deep Dive
”这篇博文。
14.5.4
扩展拓扑
Streams
的伸缩方式有两种，一种是在一个应用程序实例中运行多个线程，一种是在分
布式实例之间进行负载均衡。我们可以在一台机器上使用多线程或在多台机器上运行
Streams
应用程序
，不管是哪一种，应用程序中的所有活动线程都将均衡地分摊数据处理
工作。
Streams
引擎会将拓扑分为多个并行执行的任务
。任务数由
Streams
引擎决定，也取决于应
用程序处理的主题有多少个分区。每个任务负责处理一部分分区：它们会订阅这些分区并
从分区中读取事件。对于所读取的每一个事件，任务都会在将最终结果写入目标主题之前
按顺序执行所有的处理步骤。这些任务是
Streams
最基本的并行执行单元
，每个任务都可
以独立执行，如图
14-1
1
所示。
主题
输出主题
分区
1
任务
1
任务
2
分区
2
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