## 1 概述 ### 1.1 zookeeper 简介 - 中间件，提供协调服务 - 作用于分布式系统，发挥其优势，为大数据服务 - 支持 Java，提供 Java 和 C语言的客户端 API ### 1.2 什么是分布式系统 - 很多台计算机组成一个整体,一个整体一致对外并且处理同一请求 - 内部的每台计算机都可以相互通信(REST/RPC) - 客户端到服务端的一次请求到响应结束会经历多台计算机 ### 1.3 分布式系统的瓶颈 #### 1.3.1 zookeeper 的特性 - 一致性 数据一致性,数据按照顺序分批入库 - 原子性 事务要么成功要么失败,不会局部化 - 单一视图 客户端连接集群中的任一 zk 节点,数据都是一致的 - 可靠性 每次对 zk的操作状态都会保存在服务端 - 实时性 客户端可以读取到 zk 服务端的最新数据 ## 2 下载、安装以及配置 安装 JDK ### 2.1 单机模式 #### 2.1.1 Linux环境操作    linux etc/profile：  #### 2.1.2 Mac OS操作 ```bash $brew install zookeeper ==> Downloading https://homebrew.bintray.com/bottles/zookeeper-3.4.6_1.mavericks.bottle.2.tar.gz ######################################################################## 100.0% ==> Pouring zookeeper-3.4.6_1.mavericks.bottle.2.tar.gz ==> Caveats To have launchd start zookeeper at login: ln -sfv /usr/local/opt/zookeeper/*.plist ~/Library/LaunchAgents Then to load zookeeper now: launchctl load ~/Library/LaunchAgents/homebrew.mxcl.zookeeper.plist Or, if you don't want/need launchctl, you can just run: zkServer start ==> Summary ``` 安装成功后，在/usr/local/etc/zookeeper/目录，已有默认配置文件 ```bash $ cd /usr/local/etc/zookeeper/ $ ls zoo.cfg ``` 配置[/usr/local/etc/zookeeper/zoo.cfg] 文件 ```bash # The number of milliseconds of each tick tickTime=2000 # The number of ticks that the initial # synchronization phase can take initLimit=10 # The number of ticks that can pass between # sending a request and getting an acknowledgement syncLimit=5 # the directory where the snapshot is stored. # do not use /tmp for storage, /tmp here is just # example sakes. dataDir=/usr/local/var/run/zookeeper/data dataLogDir=/usr/local/var/run/zookeeper/log # the port at which the clients will connect clientPort=2181 ``` bin下的可执行文件：  ##### 手动下载 下载tar包解压，推荐使用3.5.x，不要使用3.6以高版本，和JDK1.8冲突，事到如今，也不要直接brew install zookeeper--默认会下载最高版本！很难用！ 下载二进制安装包： https://www.apache.org/dyn/closer.lua/zookeeper/zookeeper-3.5.10/apache-zookeeper-3.5.10-bin.tar.gz 解压缩： ```bash tar -zxvf apache-zookeeper-3.5.10-bin.tar.gz ``` 将conf目录下的zoo_sample.cfg文件更名为zoo.cfg，简单修改配置文件，自定义设置数据文件目录和日志文件目录。 新建文件夹data和log： ```bash $ zookeeper-3.5.10 ll total 48 -rw-r--r--@ 1 sss admin 11K 5 19 2022 LICENSE.txt -rw-r--r--@ 1 sss admin 432B 5 19 2022 NOTICE.txt -rw-r--r--@ 1 sss admin 1.5K 5 19 2022 README.md -rw-r--r--@ 1 sss admin 1.3K 5 19 2022 README_packaging.txt drwxr-xr-x@ 13 sss admin 416B 5 19 2022 bin drwxr-xr-x@ 5 sss admin 160B 3 8 17:49 conf drwxr-xr-x 2 sss admin 64B 3 8 17:50 data drwxr-xr-x@ 21 sss admin 672B 5 29 2022 docs drwxr-xr-x 54 sss admin 1.7K 3 8 17:46 lib drwxr-xr-x 2 sss admin 64B 3 8 17:50 log ``` 修改路径地址：dataDir 和 dataLogDir ```properties # The number of milliseconds of each tick tickTime=2000 # The number of ticks that the initial # synchronization phase can take initLimit=10 # The number of ticks that can pass between # sending a request and getting an acknowledgement syncLimit=5 # the directory where the snapshot is stored. # do not use /tmp for storage, /tmp here is just # example sakes. dataDir=/Volumes/doc/zookeeper-3.5.10/data dataLogDir=/Volumes/doc/zookeeper-3.5.10/log # the port at which the clients will connect clientPort=2181 # the maximum number of client connections. # increase this if you need to handle more clients #maxClientCnxns=60 # # Be sure to read the maintenance section of the # administrator guide before turning on autopurge. # # http://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_maintenance # # The number of snapshots to retain in dataDir #autopurge.snapRetainCount=3 # Purge task interval in hours # Set to "0" to disable auto purge feature #autopurge.purgeInterval=1 ``` ##### 配置环境变量 sudo vi ~/.bash_profile ``` export ZK_HOME=/Volumes/doc/zookeeper-3.5.10/ export PATH=$PATH:$ZK_HOME/bin ``` ```bash $ cd bin $ bin zkServer.sh start ZooKeeper JMX enabled by default Using config: /Volumes/doc/zookeeper-3.5.10/bin/../conf/zoo.cfg Starting zookeeper ... STARTED ``` ## 3 常用命令 ### 3.1 启动 执行命令zkServer： ```bash $ zkServer ZooKeeper JMX enabled by default Using config: /usr/local/etc/zookeeper/zoo.cfg Usage: ./zkServer.sh {start|start-foreground|stop|restart|status|upgrade|print-cmd} ``` zkServer status ```bash $ zkServer status ZooKeeper JMX enabled by default Using config: /usr/local/etc/zookeeper/zoo.cfg Mode: standalone ``` zkServer start ```bash $ zkServer start ZooKeeper JMX enabled by default Using config: /usr/local/etc/zookeeper/zoo.cfg Starting zookeeper ... STARTED ``` ```bash brew services start zookeeper brew services restart zookeeper ``` ### 3.2 查看运行状态 ```bash $ zkServer status ZooKeeper JMX enabled by default Using config: /usr/local/etc/zookeeper/zoo.cfg Mode: standalone ```
