欢迎关注Hadoop、Spark、Flink、Hive、Hbase、Flume等大数据资料分享微信公共账号:iteblog_hadoop
  1. 文章总数:961
  2. 浏览总数:11,509,420
  3. 评论:3873
  4. 分类目录:103 个
  5. 注册用户数:5853
  6. 最后更新:2018年10月17日
过往记忆博客公众号iteblog_hadoop
欢迎关注微信公众号:
iteblog_hadoop
大数据技术博客公众号bigdata_ai
大数据猿:
bigdata_ai

Kafka集群扩展以及重新分布分区


  我们往已经部署好的Kafka集群里面添加机器是最正常不过的需求,而且添加起来非常地方便,我们需要做的事是从已经部署好的Kafka节点中复制相应的配置文件,然后把里面的broker id修改成全局唯一的,最后启动这个节点即可将它加入到现有Kafka集群中。

  但是问题来了,新添加的Kafka节点并不会自动地分配数据,所以无法分担集群的负载,除非我们新建一个topic。但是现在我们想手动将部分分区移到新添加的Kafka节点上,Kafka内部提供了相关的工具来重新分布某个topic的分区。在重新分布topic分区之前,我们先来看看现在topic的各个分区的分布位置:

./bin/kafka-topics.sh --topic iteblog --describe --zookeeper www.iteblog.com:2181
Topic:iteblog PartitionCount:7  ReplicationFactor:2 Configs:
  Topic: iteblog  Partition: 0  Leader: 1 Replicas: 1,2 Isr: 1,2
  Topic: iteblog  Partition: 1  Leader: 2 Replicas: 2,3 Isr: 2,3
  Topic: iteblog  Partition: 2  Leader: 3 Replicas: 3,4 Isr: 3,4
  Topic: iteblog  Partition: 3  Leader: 4 Replicas: 4,1 Isr: 4,1
  Topic: iteblog  Partition: 4  Leader: 1 Replicas: 1,3 Isr: 1,3
  Topic: iteblog  Partition: 5  Leader: 2 Replicas: 2,4 Isr: 2,4
  Topic: iteblog  Partition: 6  Leader: 3 Replicas: 3,1 Isr: 3,1

从上面的输出可以看出,iteblog主题一共有7个分区,但是我们broker的个数只有4个,所以会导致某些broker维护更多的分区。现在我们在现有集群的基础上再添加一个Kafka节点,然后使用Kafka自带的kafka-reassign-partitions.sh工具来重新分布分区。该工具有三种使用模式:

  1、generate模式,给定需要重新分配的Topic,自动生成reassign plan(并不执行)
  2、execute模式,根据指定的reassign plan重新分配Partition
  3、verify模式,验证重新分配Partition是否成功

现在我们需要将原先分布在broker 1-4节点上的分区重新分布到broker 1-5节点上,借助kafka-reassign-partitions.sh工具生成reassign plan,不过我们先得按照要求定义一个文件,里面说明哪些topic需要重新分区,文件内容如下:

[iteblog@www.iteblog.com ~]$ cat topics-to-move.json
{"topics": [{"topic": "iteblog"}],
 "version":1
}

然后使用kafka-reassign-partitions.sh工具生成reassign plan


[iteblog@www.iteblog.com ~]$ bin/kafka-reassign-partitions.sh --zookeeper www.iteblog.com:2181 --topics-to-move-json-file topics-to-move.json --broker-list "1,2,3,4,5" --generate
Current partition replica assignment

{"version":1,"partitions":[{"topic":"iteblog","partition":3,"replicas":[4,1]},{"topic":"iteblog","partition":5,"replicas":[2,4]},{"topic":"iteblog","partition":4,"replicas":[1,3]},{"topic":"iteblog","partition":0,"replicas":[1,2]},{"topic":"iteblog","partition":6,"replicas":[3,1]},{"topic":"iteblog","partition":1,"replicas":[2,3]},{"topic":"iteblog","partition":2,"replicas":[3,4]}]}
Proposed partition reassignment configuration

{"version":1,"partitions":[{"topic":"iteblog","partition":3,"replicas":[3,5]},{"topic":"iteblog","partition":5,"replicas":[5,3]},{"topic":"iteblog","partition":4,"replicas":[4,1]},{"topic":"iteblog","partition":0,"replicas":[5,2]},{"topic":"iteblog","partition":6,"replicas":[1,4]},{"topic":"iteblog","partition":1,"replicas":[1,3]},{"topic":"iteblog","partition":2,"replicas":[2,4]}]}

Proposed partition reassignment configuration下面生成的就是将分区重新分布到broker 1-5上的结果。我们将这些内容保存到名为result.json文件里面(文件名不重要,文件格式也不一定要以json为结尾,只要保证内容是json即可),然后执行这些reassign plan:


[iteblog@www.iteblog.com ~]$ bin/kafka-reassign-partitions.sh --zookeeper www.iteblog.com:2181 --reassignment-json-file result.json --execute
Current partition replica assignment

{"version":1,"partitions":[{"topic":"iteblog","partition":3,"replicas":[4,1]},{"topic":"iteblog","partition":5,"replicas":[2,4]},{"topic":"iteblog","partition":4,"replicas":[1,3]},{"topic":"iteblog","partition":0,"replicas":[1,2]},{"topic":"iteblog","partition":6,"replicas":[3,1]},{"topic":"iteblog","partition":1,"replicas":[2,3]},{"topic":"iteblog","partition":2,"replicas":[3,4]}]}

Save this to use as the --reassignment-json-file option during rollback
Successfully started reassignment of partitions {"version":1,"partitions":[{"topic":"iteblog","partition":1,"replicas":[1,3]},{"topic":"iteblog","partition":5,"replicas":[5,3]},{"topic":"iteblog","partition":4,"replicas":[4,1]},{"topic":"iteblog","partition":6,"replicas":[1,4]},{"topic":"iteblog","partition":2,"replicas":[2,4]},{"topic":"iteblog","partition":0,"replicas":[5,2]},{"topic":"iteblog","partition":3,"replicas":[3,5]}]}

这样Kafka就在执行reassign plan,我们可以校验reassign plan是否执行完成:


[iteblog@www.iteblog.com ~]$ bin/kafka-reassign-partitions.sh --zookeeper www.iteblog.com:2181 --reassignment-json-file result.json --verify
Status of partition reassignment:
Reassignment of partition [iteblog,1] completed successfully
Reassignment of partition [iteblog,5] is still in progress
Reassignment of partition [iteblog,4] completed successfully
Reassignment of partition [iteblog,6] completed successfully
Reassignment of partition [iteblog,2] completed successfully
Reassignment of partition [iteblog,0] is still in progress
Reassignment of partition [iteblog,3] completed successfully

[iteblog@www.iteblog.com ~]$ bin/kafka-reassign-partitions.sh --zookeeper www.iteblog.com:2181 --reassignment-json-file result.json --verify
Status of partition reassignment:
Reassignment of partition [iteblog,1] completed successfully
Reassignment of partition [iteblog,5] completed successfully
Reassignment of partition [iteblog,4] completed successfully
Reassignment of partition [iteblog,6] completed successfully
Reassignment of partition [iteblog,2] completed successfully
Reassignment of partition [iteblog,0] completed successfully
Reassignment of partition [iteblog,3] completed successfully

可以看出,分区正在Reassignment的状态是still in progress;如果分区Reassignment完成则completed successfully,然后我们就可以看到分区已经按照生成的reassign plan进行,我们可以看下topic各个分区现在的分布情况:


[iteblog@www.iteblog.com ~]$ ./bin/kafka-topics.sh --topic iteblog --describe --zookeeper www.iteblog.com:2181
Topic:iteblog PartitionCount:7  ReplicationFactor:2 Configs:
  Topic: iteblog  Partition: 0  Leader: 5 Replicas: 5,2 Isr: 2,5
  Topic: iteblog  Partition: 1  Leader: 1 Replicas: 1,3 Isr: 3,1
  Topic: iteblog  Partition: 2  Leader: 2 Replicas: 2,4 Isr: 4,2
  Topic: iteblog  Partition: 3  Leader: 3 Replicas: 3,5 Isr: 3,5
  Topic: iteblog  Partition: 4  Leader: 1 Replicas: 4,1 Isr: 1,4
  Topic: iteblog  Partition: 5  Leader: 5 Replicas: 5,3 Isr: 3,5
  Topic: iteblog  Partition: 6  Leader: 1 Replicas: 1,4 Isr: 1,4

分区的分布的确和操作之前不一样了,broker 5上已经有分区分布上去了。但是仔细的同学应该可以发现,broker 4上居然没有分区的Leader,这肯定不是我们想要的!所以使用kafka-reassign-partitions.sh工具生成的reassign plan只是一个建议,方便大家而已。其实我们自己完全可以编辑一个reassign plan,然后执行它,如下:

{
    "version": 1, 
    "partitions": [
        {
            "topic": "iteblog", 
            "partition": 0, 
            "replicas": [
                1, 
                2
            ]
        }, 
        {
            "topic": "iteblog", 
            "partition": 1, 
            "replicas": [
                2, 
                3
            ]
        }, 
        {
            "topic": "iteblog", 
            "partition": 2, 
            "replicas": [
                3, 
                4
            ]
        }, 
        {
            "topic": "iteblog", 
            "partition": 3, 
            "replicas": [
                4, 
                5
            ]
        }, 
        {
            "topic": "iteblog", 
            "partition": 4, 
            "replicas": [
                5, 
                1
            ]
        }, 
        {
            "topic": "iteblog", 
            "partition": 5, 
            "replicas": [
                1, 
                3
            ]
        }, 
        {
            "topic": "iteblog", 
            "partition": 6, 
            "replicas": [
                2, 
                4
            ]
        }
    ]
}

将上面的json数据文件保存到result.json文件中,然后也是执行它:


[iteblog@www.iteblog.com ~]$ bin/kafka-reassign-partitions.sh --zookeeper www.iteblog.com:2181 --reassignment-json-file result.json --execute

等这个reassign plan执行完,我们再来看看分区的分布:


[iteblog@www.iteblog.com ~]$  ./bin/kafka-topics.sh --topic iteblog --describe --zookeeper www.iteblog.com:2181
Topic:iteblog PartitionCount:7  ReplicationFactor:2 Configs:
  Topic: iteblog  Partition: 0  Leader: 1 Replicas: 1,2 Isr: 2,1
  Topic: iteblog  Partition: 1  Leader: 2 Replicas: 2,3 Isr: 3,2
  Topic: iteblog  Partition: 2  Leader: 3 Replicas: 3,4 Isr: 4,3
  Topic: iteblog  Partition: 3  Leader: 4 Replicas: 4,5 Isr: 5,4
  Topic: iteblog  Partition: 4  Leader: 5 Replicas: 5,1 Isr: 1,5
  Topic: iteblog  Partition: 5  Leader: 1 Replicas: 1,3 Isr: 3,1
  Topic: iteblog  Partition: 6  Leader: 2 Replicas: 2,4 Isr: 4,2

果然已经按照我们需求分布了。。

本博客文章除特别声明,全部都是原创!
转载本文请加上:转载自过往记忆(https://www.iteblog.com/)
本文链接: 【Kafka集群扩展以及重新分布分区】(https://www.iteblog.com/archives/1611.html)
喜欢 (18)
分享 (0)
发表我的评论
取消评论

表情
本博客评论系统带有自动识别垃圾评论功能,请写一些有意义的评论,谢谢!
(2)个小伙伴在吐槽
  1. 写得真好,受益,最后那个手写plan,Replicas配置不应该出现6、7吧
    Riordon2016-04-19 08:32 回复
    • 感谢指正,已经纠正了。
      w3970907702016-04-19 13:04 回复