Kafka介绍
AMPQ
ampq定义
AMPQ(Advanced Message Queuing Protocal),是一种链接协议，即提供统一消息服务的应用层标准高级消息队列协议。
使用AMPQ实现的框架是：kafka，RabbitMQ
Kafka
kafka支持动态扩容（zookeeper组件支持）
RabbitMQ、ActiveMQ最大的特点:消息消费完成消息就删除
kafka特点：所有的消费会自动保存两天
RabbitMQ 是使用 Erlang 编写的一个开源的消息队列，本身支持很多的协议：AMQP，XMPP, SMTP, STOMP，也正因如此，它非常重量级，更适合于企业级的开发。同时实现了 Broker 构架，这意味着消息在发送给客户端时先在中心队列排队。对路由，负载均衡或者数据持久化都有很好的支持。
kafka原理
Kafka作为一个集群可以运行在多个可跨多个数据中心的服务器上。
kafka集群以称为主题的类别储存记录流
每个记录由一个键，一个值和一个时间戳组成
术语
producer :生产者【解释：发布消息的对象称之为主题生产者(Kafka topic producer)】
consumer :消费者，订阅消息并处理发布的消息的种子的对象称之为主题消费者(consumers)
topic : 标签(实际上可以看作队列)，【解释：kafka将消息种子feed分类，每一类的消息就是一个主题(Topic)】
broker:已发布的消息保存在一组服务器中，称之为Kafka集群。集群中的每一个服务器都是一个代理(Broker). 消费者可以订阅一个或多个主题（topic），并从Broker拉数据，从而消费这些已发布的消息。
四个核心API
1.应用程序使用Producer API发布消息到1个或多个topic（主题）。
2.应用程序使用Consumer API来订阅一个或多个topic，并处理产生的消息。
3.应用程序使用Stream API充当一个流处理器，从1个或多个topic消息输入流，并生产一个输出流到一个1个或多个输出topic，有效地将输入流转换输出流。
4：Connector API允许构建或运行可重复使用的生产者或消费者，将topic连接到现有的应用程序或数据系统。例如：一个关系数据库的连接器可捕获每一个变化
主题和日志（略）
生产者
消费者
常用命令
管理
## 创建主题（4个分区，2个副本）
bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 2 --partitions 4 --topic test
查询
## 查询集群描述
bin/kafka-topics.sh --describe --zookeeper
## 消费者列表查询
bin/kafka-topics.sh --zookeeper 127.0.0.1:2181 --list
## 新消费者列表查询（支持0.9版本+）
bin/kafka-consumer-groups.sh --new-consumer --bootstrap-server localhost:9092 --list
## 显示某个消费组的消费详情（仅支持offset存储在zookeeper上的）
bin/kafka-run-class.sh kafka.tools.ConsumerOffsetChecker --zookeeper localhost:2181 --group test
## 显示某个消费组的消费详情（支持0.9版本+）
bin/kafka-consumer-groups.sh --new-consumer --bootstrap-server localhost:9092 --describe --group test-consumer-group
发送和消费
## 生产者
bin/kafka-console-producer.sh --broker-list localhost:9092 --topic test
## 消费者
bin/kafka-console-consumer.sh --zookeeper localhost:2181 --topic test
## 新生产者（支持0.9版本+）
bin/kafka-console-producer.sh --broker-list localhost:9092 --topic test --producer.config config/producer.properties
## 新消费者（支持0.9版本+）
bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic test --new-consumer --from-beginning --consumer.config config/consumer.properties
## 高级点的用法
bin/kafka-simple-consumer-shell.sh --brist localhost:9092 --topic test --partition 0 --offset 1234 --max-messages 10
平衡leader
bin/kafka-preferred-replica-election.sh --zookeeper zk_host:port/chroot
kafka自带压测命令
bin/kafka-producer-perf-test.sh --topic test --num-records 100 --record-size 1 --throughput 100 --producer-props bootstrap.servers=localhost:9092
增加副本
1：创建规则json
cat > increase-replication-factor.json <<EOF
{"version":1, "partitions":[
{"topic":"__consumer_offsets","partition":0,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":1,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":2,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":3,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":4,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":5,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":6,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":7,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":8,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":9,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":10,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":11,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":12,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":13,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":14,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":15,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":16,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":17,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":18,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":19,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":20,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":21,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":22,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":23,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":24,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":25,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":26,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":27,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":28,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":29,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":30,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":31,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":32,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":33,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":34,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":35,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":36,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":37,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":38,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":39,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":40,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":41,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":42,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":43,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":44,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":45,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":46,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":47,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":48,"replicas":[0,1]},
{"topic":"__consumer_offsets","partition":49,"replicas":[0,1]}]
}
EOF
2：执行
bin/kafka-reassign-partitions.sh --zookeeper localhost:2181 --reassignment-json-file increase-replication-factor.json --execute
3:验证
bin/kafka-reassign-partitions.sh --zookeeper localhost:2181 --reassignment-json-file increase-replication-factor.jso
来源：https://www.cnblogs.com/mlan/p/11084526.html
