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,可以为大数据服务
- 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
2.1.2 Mac OS操作
代码语言:javascript复制$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
- 安装后,在/usr/local/etc/zookeeper/目录下,已经有了默认的配置文件
- 配置[/usr/local/etc/zookeeper/zoo.cfg] 文件
# 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
# 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
- 在bin下有很多可执行文件
3 常用命令
3.1 启动
- 执行命令zkServer
- zkServer status
- zkServer start