Zookeeper技術介紹

 ZooKeeper是一個分佈式的，開放源碼的分佈式應用程序協調服務，是Google的Chubby一個開源的實現，是Hadoop和Hbase的重要組件。它是一個爲分佈式應用提供一致性服務的軟件，提供的功能包括：配置維護、域名服務、分佈式同步、組服務等。

  ZooKeeper的目標就是封裝好複雜易出錯的關鍵服務，將簡單易用的接口和性能高效、功能穩定的系統提供給用戶。

  ZooKeeper包含一個簡單的原語集提供Java和C的接口。

  ZooKeeper代碼版本中，提供了分佈式獨享鎖、選舉、隊列的接口，代碼在zookeeper-3.4.3\src\recipes。其中分佈鎖和隊列有Java和C兩個版本，選舉只有Java版本。

主要做用是用來解決分佈式應用中常常遇到的一些數據管理問題，如集羣管理、統一命名管理、分佈式配置管理、分佈式消息隊列、分佈式鎖、分佈式通知協調

官方網站：https://zookeeper.apache.org/

zookeeper體系結構

  zk的集羣中有一個Leader，有一個或多個follower，它們之間是相互通訊的，而後還存在一個客戶端用來訪問zk服務器。

  服務器端具備fast fail特性，一旦主故障後，會選舉從成爲新的主，主從模式是目前最多見的模式。

 

 

zookeeper名字空間由節點NODE構成,相似於文件系統,其中各個節點至關於目錄和文件,經過路徑做爲惟一標識,與文件系統不一樣的是,每一個節點具備與之對應的數據內容,同時也能夠具備子節點,它用來存儲協調數據,如狀態、配置、位置信息、每一個節點存儲的數據量很小，KB級別.

watches介紹

zk對節點的增、刪、改、查均可以觸發監聽

watch事件是一次性觸發器，當它監視的數據發生變化時，通知設置了該客戶端

Zookeeper安裝佈署

四臺服務器

zk-001  10.0.0.8

zk-002  10.0.0.9

zk-003  10.0.0.10

zk-client 10.0.0.100

 

下載安裝JDK環境

tar zxf jdk-8u60-linux-x64.tar.gz

mv jdk1.8.0_60 /usr/local/jdk

export JAVA_HOME=/usr/local/jdk

export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

export PATH=$JAVA_HOME/bin:$PATH

source /etc/profile

java -version

[root@zk-001 ~]# java -version

java version "1.8.0_60"

Java(TM) SE Runtime Environment (build 1.8.0_60-b27)

Java HotSpot(TM) 64-Bit Server VM (build 25.60-b23, mixed mode)

下載安裝zookeeper

wget http://www.apache.org/dist/zookeeper/zookeeper-3.4.6/zookeeper-3.4.6.tar.gz

tar zxf zookeeper-3.4.6.tar.gz

mv zookeeper-3.4.6 /usr/local/zookeeper

[root@zk-001 ~]# cd /usr/local/zookeeper/

配置環境變量

export ZOOKEEPER_HOME=/usr/local/zookeeper

export PATH=$ZOOKEEPER_HOME/bin:$PATH

source /etc/profile

Zookeeper的配置

三種配置模式

一、僞分佈模式

二、徹底分佈式

三、獨立模式

 

獨立模式配置

[root@zk-001 zookeeper]# cd conf/

[root@zk-001 conf]# ll

total 12

-rw-rw-r-- 1 1000 1000  535 Feb 20  2014 configuration.xsl

-rw-rw-r-- 1 1000 1000 2161 Feb 20  2014 log4j.properties

-rw-rw-r-- 1 1000 1000  922 Feb 20  2014 zoo_sample.cfg

[root@zk-001 conf]# cp zoo_sample.cfg zoo.cfg

[root@zk-001 conf]#vim zoo.cfg

# The number of milliseconds of each tick

tickTime=2000   #心跳檢查週期（單位毫秒）

# the directory where the snapshot is stored.

# do not use /tmp for storage, /tmp here is just

# example sakes.

dataDir=/tmp/zookeeper  #存放數據目錄

# the port at which the clients will connect

clientPort=2181  #供客戶端鏈接的端口

 

集羣模式配置

tickTime=2000

initLimit=10

syncLimit=5

//server.n=host:port1:port2 

數字N必須是myid中的值，Myid文件位於dataDIR目錄下，只能是一個n值

//port1:leader端口，做爲leader時，供follower鏈接的端口

//port2:選舉端口，選舉leader時，供follower鏈接的端口

server.1=s1:2888:3888

server.2=s2:2888:3888

server.3=s3:2888:3888

zk處理集羣故障的算法是2n+1,最好在奇數機器數佈署，若是同臺服務器配置多實例就要注意端口衝突問題，能夠寫成以下

server.1=s1:2888:3888

server.2=s2:2889:3889

server.3=s3:2887:3887

 

配置過程以下

配置hosts文件

vim /etc/hosts

10.0.0.8 zk-001

10.0.0.9 zk-002

10.0.0.10 zk-003               

配置各服務器配置文件

[root@zk-001 conf]# mkdir /tmp/zookeeper

[root@zk-001 conf]# cd /tmp/zookeeper/

[root@zk-001 zookeeper]# echo 8 >myid

[root@zk-001 conf]# egrep -v "^#|^$" zoo.cfg

tickTime=2000

initLimit=10

syncLimit=5

dataDir=/tmp/zookeeper

clientPort=2181

server.8=zk-001:2888:3888

server.9=zk-002:2888:3888

server.10=zk-003:2888:3888

[root@zk-002 ~]# mkdir /tmp/zookeeper

[root@zk-002 ~]# cd /tmp/zookeeper/

[root@zk-002 zookeeper]# echo 9 >myid

[root@zk-002 zookeeper]# ll

total 4

-rw-r--r-- 1 root root 2 May 13 15:51 myid

[root@zk-002 zookeeper]# cd /usr/local/zookeeper/conf/

[root@zk-002 conf]# cp zoo_sample.cfg zoo.cfg

[root@zk-002 conf]# vim zoo.cfg

tickTime=2000

initLimit=10

syncLimit=5

dataDir=/tmp/zookeeper

clientPort=2181

server.8=zk-001:2888:3888

server.9=zk-002:2888:3888

server.10=zk-003:2888:3888

[root@zk-003 ~]# mkdir /tmp/zookeeper

[root@zk-003 ~]# cd /tmp/zookeeper/

[root@zk-003 zookeeper]# echo 10 >myid

[root@zk-003 zookeeper]# cd /usr/local/zookeeper/conf/

[root@zk-003 conf]# cp zoo_sample.cfg zoo.cfg

[root@zk-003 conf]# vim zoo.cfg

tickTime=2000

initLimit=10

syncLimit=5

dataDir=/tmp/zookeeper

clientPort=2181

server.8=zk-001:2888:3888

server.9=zk-002:2888:3888

server.10=zk-003:2888:3888

啓動服務

[root@zk-001 bin]# zkServer.sh start

JMX enabled by default

Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg

Starting zookeeper ... STARTED

[root@zk-002 bin]# zkServer.sh start

JMX enabled by default

Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg

Starting zookeeper ... STARTED

[root@zk-003 bin]# zkServer.sh start

JMX enabled by default

Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg

Starting zookeeper ... STARTED

查看狀態

[root@zk-001 conf]# zkServer.sh status

JMX enabled by default

Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg

Mode: follower

[root@zk-002 conf]# zkServer.sh status

JMX enabled by default

Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg

Mode: follower

[root@zk-003 conf]# zkServer.sh status

JMX enabled by default

Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg

Mode: leader

能夠看出已經選舉leader出來了，代表配置是正確的

測試leader故障後切換狀況

[root@zk-003 conf]# jps

2694 Jps

2430 QuorumPeerMain

[root@zk-003 conf]# kill 2430

[root@zk-003 conf]# jps     

2724 Jps

[root@zk-002 conf]# zkServer.sh status

JMX enabled by default

Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg

Mode: follower

[root@zk-001 conf]# zkServer.sh status

JMX enabled by default

Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg

Mode: leader

能夠看出zk-001這臺服務器被選舉成新的leader了

 

Zookeeper客戶端四字符指令

conf 配置信息

cons 鏈接信息

dump 未處理會話節點

envi 環境信息

reqs 未處理請求   

stat 統計信息

wchs 服務器watch的詳細信息

wchp 列出指定路徑下服務器信息

[root@zk-003 ~]# echo conf | nc 10.0.0.8 2181

clientPort=2181

dataDir=/tmp/zookeeper/version-2

dataLogDir=/tmp/zookeeper/version-2

tickTime=2000

maxClientCnxns=60

minSessionTimeout=4000

maxSessionTimeout=40000

serverId=8

initLimit=10

syncLimit=5

electionAlg=3

electionPort=3888

quorumPort=2888

peerType=0

[root@zk-003 ~]# echo envi | nc 10.0.0.8 2181   

Environment:

zookeeper.version=3.4.6-1569965, built on 02/20/2014 09:09 GMT

host.name=zk-001

java.version=1.8.0_121

java.vendor=Oracle Corporation

java.home=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.121-0.b13.el6_8.x86_64/jre

java.class.path=/usr/local/zookeeper/bin/../build/classes:/usr/local/zookeeper/bin/../build/lib/*.jar:/usr/local/zookeeper/bin/../lib/slf4j-log4j12-1.6.1.jar:/usr/local/zookeeper/bin/../lib/slf4j-api-1.6.1.jar:/usr/local/zookeeper/bin/../lib/netty-3.7.0.Final.jar:/usr/local/zookeeper/bin/../lib/log4j-1.2.16.jar:/usr/local/zookeeper/bin/../lib/jline-0.9.94.jar:/usr/local/zookeeper/bin/../zookeeper-3.4.6.jar:/usr/local/zookeeper/bin/../src/java/lib/*.jar:/usr/local/zookeeper/bin/../conf:

java.library.path=/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib

java.io.tmpdir=/tmp

java.compiler=<NA>

os.name=Linux

os.arch=amd64

os.version=2.6.32-504.el6.x86_64

user.name=root

user.home=/root

user.dir=/usr/local/zookeeper/conf

[root@zk-003 ~]# echo stat | nc 10.0.0.8 2181       

Zookeeper version: 3.4.6-1569965, built on 02/20/2014 09:09 GMT

Clients:

 /10.0.0.10:41192[0](queued=0,recved=1,sent=0)

Latency min/avg/max: 0/0/0

Received: 4

Sent: 3

Connections: 1

Outstanding: 0

Zxid: 0x200000000

Mode: leader

Node count: 4

Zookeeper客戶端命令

經過zkCli.sh 鏈接服務器

zkCli.sh -server zk-001:2181

         -server 10.0.0.9:2181

[root@zk-001 ~]# zkCli.sh -server zk-002:2181             

Connecting to zk-002:2181

WATCHER::

WatchedEvent state:SyncConnected type:None path:null

[zk: zk-002:2181(CONNECTED) 0] h ##幫助命令

ZooKeeper -server host:port cmd args

        stat path [watch]

        set path data [version]

        ls path [watch]

        delquota [-n|-b] path

        ls2 path [watch]

        setAcl path acl

        setquota -n|-b val path

        history

        redo cmdno

        printwatches on|off

        delete path [version]

        sync path

        listquota path

        rmr path

        get path [watch]

        create [-s] [-e] path data acl

        addauth scheme auth

        quit

        getAcl path

        close

        connect host:port

[zk: zk-002:2181(CONNECTED) 1] ls /             

#列出目錄下內容

[zookeeper]

[zk: zk-002:2181(CONNECTED) 2] ls /zookeeper

[quota]

[zk: zk-002:2181(CONNECTED) 3] ls /zookeeper/quota

[]

[zk: zk-002:2181(CONNECTED) 4] create /root testfile  

#建立目錄及數據

Created /root

[zk: zk-002:2181(CONNECTED)5]get /root #獲取數據

testfile

cZxid = 0x200000002

ctime = Sat May 13 20:09:52 CST 2017

mZxid = 0x200000002

mtime = Sat May 13 20:09:52 CST 2017

pZxid = 0x200000002

cversion = 0

dataVersion = 0

aclVersion = 0

ephemeralOwner = 0x0

dataLength = 8

numChildren = 0

[zk: zk-002:2181(CONNECTED) 6] set /root testfile-001

cZxid = 0x200000002

ctime = Sat May 13 20:09:52 CST 2017

mZxid = 0x200000003

mtime = Sat May 13 21:04:17 CST 2017

pZxid = 0x200000002

cversion = 0

dataVersion = 1

aclVersion = 0

ephemeralOwner = 0x0

dataLength = 12

numChildren = 0

須要注意的是ZK是不能一次建立多級節點的

[zk: zk-002:2181(CONNECTED) 7] create /root/s1/s1-1

[zk: zk-002:2181(CONNECTED) 8] ls /root #提示是空

[]

[zk: zk-002:2181(CONNECTED) 9] create /root/s1 s1-data

Created /root/s1

[zk: zk-002:2181(CONNECTED) 10] create /root/s2 s2-data

Created /root/s2

[zk: zk-002:2181(CONNECTED) 11] create /root/s3 s3-data

Created /root/s3

[zk: zk-002:2181(CONNECTED) 13] ls /root

[s3, s1, s2]

查看狀態

[zk: zk-002:2181(CONNECTED) 14] stat /root

cZxid = 0x200000002

ctime = Sat May 13 20:09:52 CST 2017

mZxid = 0x200000003

mtime = Sat May 13 21:04:17 CST 2017

pZxid = 0x200000006

cversion = 3

dataVersion = 1

aclVersion = 0

ephemeralOwner = 0x0

dataLength = 12

numChildren = 3

刪除目錄

[zk: zk-002:2181(CONNECTED) 15] delete /root/s3

[zk: zk-002:2181(CONNECTED) 16] ls /root

[s1, s2]

斷開鏈接

[zk: zk-002:2181(CONNECTED) 17] close

2017-05-13 21:13:00,603 [myid:] - INFO[main:ZooKeeper@684] - Session: 0x95c0122efa50000 closed

2017-05-13 21:13:00,604 [myid:] - INFO[main-EventThread:ClientCnxn$EventThread@512] - EventThread shut down

從新鏈接

因爲ZK服務器間的數據是一致的，所以此次我鏈接其它服務器

[zk: zk-002:2181(CLOSED) 18] connect zk-001:2181

[zk: zk-001:2181(CONNECTED) 19] get /root

testfile-001

cZxid = 0x200000002

ctime = Sat May 13 20:09:52 CST 2017

mZxid = 0x200000003

mtime = Sat May 13 21:04:17 CST 2017

pZxid = 0x200000007

cversion = 4

dataVersion = 1

aclVersion = 0

ephemeralOwner = 0x0

dataLength = 12

numChildren = 2

[zk: zk-001:2181(CONNECTED) 20] get /root/s1

s1-data

cZxid = 0x200000004

ctime = Sat May 13 21:07:42 CST 2017

mZxid = 0x200000004

mtime = Sat May 13 21:07:42 CST 2017

pZxid = 0x200000004

cversion = 0

dataVersion = 0

aclVersion = 0

ephemeralOwner = 0x0

dataLength = 7

numChildren = 0