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

linux etc/profile

2.1.2 Mac OS操作

$brew install zookeeper
==&gt; Downloading https://homebrew.bintray.com/bottles/zookeeper-3.4.6_1.mavericks.bottle.2.tar.gz
######################################################################## 100.0%
==&gt; Pouring zookeeper-3.4.6_1.mavericks.bottle.2.tar.gz
==&gt; 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
==&gt; 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