1-zookeeper基本原理和使用

1 分布式应用

1.1 分布式系统原理

　　在一个网络中，每台服务器上各跑一个应用，然后彼此连接起来就组成一套系统。比如提供完成的游戏服务，需要有认证应用，道具应用，积分应用，游戏主应用等，应用并非跑在一台服务器上，而是分布在整个网络中，整合起来提供服务。

1.2 分布式协调技术

　　解决分布式环境中的资源调度问题。分布式锁是其核心技术。比如有三个进程物理分布在网络中，有一个磁盘资源，原本三个进程会对它发生资源争抢，互相干扰。分布式调度就是使用调度器，让进程1先访问磁盘，然后用分布式锁对资源进行上锁，使其他进程无法访问。进程1用完磁盘后，锁就释放掉。调度器分配其他进程来使用资源，并且上锁独占该资源。这样，就实现了分布式环境中资源的有序调度。

1.3 分布式锁应用

　　google开发了非开源的chbby实现，而后雅虎模仿开发了zookeeper，并且开源、捐给了apache。zookeeper在可用性、性能、一致性上都有非常好的表现。

　　zeekeeper目前使用广泛。企业在构建分布式系统时，可以使用zookeeper为基础来做。

2 zook配置

　　centos7默认会安装openjdk，卸载。然后安装jdk，配置env。（在PATH中，java的路径要写在前面，不然会读取原先的openjdk）

[root@yhzk02 ~]# rpm -ivh jdk-8u171-linux-x64.rpm
#安装jdk
 
[root@yhzk02 latest]# rpm -qa | grep openjdk
java-1.8.0-openjdk-1.8.0.131-11.b12.el7.x86_64
java-1.8.0-openjdk-headless-1.8.0.131-11.b12.el7.x86_64
[root@yhzk02 latest]# rpm -e java-1.8.0-openjdk java-1.8.0-openjdk-headless --nodeps
#卸载openjdk
 
vim /etc/profile.d/java.sh
export JRE_HOME=/usr/java/latest/jre
export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib
 
[root@yhzk02 latest]# . /etc/profile.d/java.sh
[root@yhzk02 latest]# java -version
java version "1.8.0_171"
Java(TM) SE Runtime Environment (build 1.8.0_171-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.171-b11, mixed mode)
#配置env并检查

　　

zook包不用安装，直接放进/usr/local目录下，解包。然后需要写一个conf/zoo.cfg文件。

[root@yhzk02 zookeeper-3.4.11]# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.10.12 yhzk01
192.168.10.13 yhzk02
192.168.10.14 yhzk03
#先设定hosts

tickTime=2000
initLimit=10
syncLimit=5
dataDir=/zookeeperdata
clientPort=2181
server.1=yhzk01:2888:3888
server.2=yhzk02:2888:3888
server.3=yhzk03:2888:3888
#然后写conf/zoo.cfg文件。
#ticktime：心跳信息检测时间，最小会话超时时间为ticktime的两倍，单位为毫秒。
#dataDir：内存db快照。
#clientPort：监听客户端访问的端口
#server.id=hostname:port（选举端口）:port（通信端口）。

　　

[root@yhzk01 /]# cat /zookeeperdata/myid
1
#在每个集群节点的dataDir下创建ID标识文件。

　　

然后可以使用zkServer.sh start启动。（按myid按顺序启动，1->2->3）

启动后，在bin/下有一个zookeeper.out文件，是zook的日志文件。正确配置会有如下输出

2018-04-20 09:47:31,682 [myid:] - INFO  [main:QuorumPeerConfig@136] - Reading configuration from: /usr/local/zookeeper-3.4.11/bin/../conf/
zoo.cfg
2018-04-20 09:47:31,703 [myid:] - INFO  [main:QuorumPeer$QuorumServer@184] - Resolved hostname: yhzk01 to address: yhzk01/192.168.10.12
2018-04-20 09:47:31,703 [myid:] - INFO  [main:QuorumPeer$QuorumServer@184] - Resolved hostname: yhzk03 to address: yhzk03/192.168.10.14
2018-04-20 09:47:31,704 [myid:] - INFO  [main:QuorumPeer$QuorumServer@184] - Resolved hostname: yhzk02 to address: yhzk02/192.168.10.13
2018-04-20 09:47:31,704 [myid:] - INFO  [main:QuorumPeerConfig@398] - Defaulting to majority quorums
2018-04-20 09:47:31,707 [myid:2] - INFO  [main:DatadirCleanupManager@78] - autopurge.snapRetainCount set to 3
2018-04-20 09:47:31,707 [myid:2] - INFO  [main:DatadirCleanupManager@79] - autopurge.purgeInterval set to 0
2018-04-20 09:47:31,707 [myid:2] - INFO  [main:DatadirCleanupManager@101] - Purge task is not scheduled.
2018-04-20 09:47:31,726 [myid:2] - INFO  [main:QuorumPeerMain@130] - Starting quorum peer
2018-04-20 09:47:31,739 [myid:2] - INFO  [main:ServerCnxnFactory@117] - Using org.apache.zookeeper.server.NIOServerCnxnFactory as server c
onnection factory
2018-04-20 09:47:31,743 [myid:2] - INFO  [main:NIOServerCnxnFactory@89] - binding to port 0.0.0.0/0.0.0.0:2181
2018-04-20 09:47:31,751 [myid:2] - INFO  [main:QuorumPeer@1158] - tickTime set to 2000
2018-04-20 09:47:31,751 [myid:2] - INFO  [main:QuorumPeer@1204] - initLimit set to 10
2018-04-20 09:47:31,752 [myid:2] - INFO  [main:QuorumPeer@1178] - minSessionTimeout set to -1
2018-04-20 09:47:31,752 [myid:2] - INFO  [main:QuorumPeer@1189] - maxSessionTimeout set to -1
2018-04-20 09:47:31,763 [myid:2] - INFO  [main:QuorumPeer@1467] - QuorumPeer communication is not secured!
2018-04-20 09:47:31,764 [myid:2] - INFO  [main:QuorumPeer@1496] - quorum.cnxn.threads.size set to 20
2018-04-20 09:47:31,779 [myid:2] - INFO  [ListenerThread:QuorumCnxManager$Listener@736] - My election bind port: yhzk02/192.168.10.13:3888
2018-04-20 09:47:31,797 [myid:2] - INFO  [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:QuorumPeer@909] - LOOKING
2018-04-20 09:47:31,798 [myid:2] - INFO  [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:FastLeaderElection@820] - New election. My id =  2, prop
osed zxid=0x0

2018-04-20 10:02:15,286 [myid:2] - INFO  [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:QuorumPeer$QuorumServer@184] - Resolved hostname: yhzk03
 to address: yhzk03/192.168.10.14
2018-04-20 10:02:15,286 [myid:2] - INFO  [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:FastLeaderElection@854] - Notification time out: 60000
2018-04-20 10:02:44,463 [myid:2] - INFO  [yhzk02/192.168.10.13:3888:QuorumCnxManager$Listener@743] - Received connection request /192.168.
10.12:33318
2018-04-20 10:02:44,561 [myid:2] - INFO  [WorkerReceiver[myid=2]:FastLeaderElection@602] - Notification: 1 (message format version), 1 (n.
leader), 0x0 (n.zxid), 0x1 (n.round), LOOKING (n.state), 1 (n.sid), 0x0 (n.peerEpoch) LOOKING (my state)
2018-04-20 10:02:44,561 [myid:2] - INFO  [WorkerReceiver[myid=2]:FastLeaderElection@602] - Notification: 1 (message format version), 3 (n.
leader), 0x0 (n.zxid), 0x1 (n.round), LOOKING (n.state), 1 (n.sid), 0x0 (n.peerEpoch) LOOKING (my state)
2018-04-20 10:02:44,577 [myid:2] - INFO  [WorkerSender[myid=2]:QuorumCnxManager@347] - Have smaller server identifier, so dropping the con
nection: (3, 2)
2018-04-20 10:02:44,578 [myid:2] - INFO  [WorkerReceiver[myid=2]:FastLeaderElection@602] - Notification: 1 (message format version), 3 (n.
leader), 0x0 (n.zxid), 0x1 (n.round), LOOKING (n.state), 2 (n.sid), 0x0 (n.peerEpoch) LOOKING (my state)
2018-04-20 10:02:44,624 [myid:2] - INFO  [yhzk02/192.168.10.13:3888:QuorumCnxManager$Listener@743] - Received connection request /192.168.
10.14:56120
2018-04-20 10:02:44,680 [myid:2] - INFO  [WorkerReceiver[myid=2]:FastLeaderElection@602] - Notification: 1 (message format version), 3 (n.
leader), 0x0 (n.zxid), 0x1 (n.round), LOOKING (n.state), 3 (n.sid), 0x0 (n.peerEpoch) LOOKING (my state)
2018-04-20 10:02:44,888 [myid:2] - INFO  [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:QuorumPeer@979] - FOLLOWING
2018-04-20 10:02:44,901 [myid:2] - INFO  [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:Learner@86] - TCP NoDelay set to: true
2018-04-20 10:02:44,927 [myid:2] - INFO  [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:Environment@100] - Server environment:zookeeper.version=
3.4.11-37e277162d567b55a07d1755f0b31c32e93c01a0, built on 11/01/2017 18:06 GMT
2018-04-20 10:02:44,927 [myid:2] - INFO  [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:Environment@100] - Server environment:host.name=yhzk02
2018-04-20 10:02:44,927 [myid:2] - INFO  [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:Environment@100] - Server environment:java.version=1.8.0
_171
2018-04-20 10:02:44,928 [myid:2] - INFO  [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:Environment@100] - Server environment:java.vendor=Oracle
 Corporation
2018-04-20 10:02:44,928 [myid:2] - INFO  [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:Environment@100] - Server environment:java.home=/usr/jav
a/jdk1.8.0_171-amd64/jre
2018-04-20 10:02:44,928 [myid:2] - INFO  [QuorumPeer[myid=2]/0:0:0:0:0:0:0:0:2181:Environment@100] - Server environment:java.class.path=/u
sr/local/zookeeper-3.4.11/bin/../build/classes:/usr/local/zookeeper-3.4.11/bin/../build/lib/*.jar:/usr/local/zookeeper-3.4.11/bin/../lib/s
lf4j-log4j12-1.6.1.jar:/usr/local/zookeeper-3.4.11/bin/../lib/slf4j-api-1.6.1.jar:/usr/local/zookeeper-3.4.11/bin/../lib/netty-3.10.5.Fina
l.jar:/usr/local/zookeeper-3.4.11/bin/../lib/log4j-1.2.16.jar:/usr/local/zookeeper-3.4.11/bin/../lib/jline-0.9.94.jar:/usr/local/zookeeper
-3.4.11/bin/../lib/audience-annotations-0.5.0.jar:/usr/local/zookeeper-3.4.11/bin/../zookeeper-3.4.11.jar:/usr/local/zookeeper-3.4.11/bin/
../src/java/lib/*.jar:/usr/local/zookeeper-3.4.11/bin/../conf:.:/usr/java/latest/lib/dt.jar:/usr/java/latest/lib/tools.jar:/usr/java/lates
t/jre/lib

　　

4 zook工具

4.1 启停&状态：

zkServer.sh {start|stop|status}

使用telnet可以查看更多信息。

clients是处于tcp长连接状态的客户端及数据收发信息。

[root@yhzk01 bin]# telnet 127.0.0.1 2181
stat
Zookeeper version: 3.4.11-37e277162d567b55a07d1755f0b31c32e93c01a0, built on 11/01/2017 18:06 GMT
Clients:
 /127.0.0.1:56962[0](queued=0,recved=1,sent=0)
 
Latency min/avg/max: 0/0/0
Received: 5
Sent: 4
Connections: 1
Outstanding: 0
Zxid: 0x0
Mode: follower
Node count: 4

　　

4.2 zkCli工具

集群之间是互通的，在一个zook操作，另外两台上也会同步。

./zkCli.sh -server 127.0.0.1:22181
#指定服务器和端口

　　

4.2.1 查看目录结构 && 状态 && 设立WATCHER

[zk: localhost:2181(CONNECTED) 0] ls /
[zookeeper]
#查看/节点下的子节点
[zk: localhost:2181(CONNECTED) 27] ls /worker
[process3, process1, process2]
#查看/worker下面的子节点
[zk: localhost:2181(CONNECTED) 30] ls /worker/process1 true
[121]
[zk: localhost:2181(CONNECTED) 31]
WATCHER::
 
WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/worker/process1
#监听/worker/process1子节点数量。在其他id中创建子节点，本id会收到WATCHER。
 
[zk: localhost:2181(CONNECTED) 18] stat /yinhe
cZxid = 0x500000003
ctime = Thu Apr 26 11:06:17 CST 2018　　#节点创建时间
mZxid = 0x500000003
mtime = Thu Apr 26 11:06:17 CST 2018　　#节点修改时间
pZxid = 0x500000003
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 0
numChildren = 0　　#子节点数量，类似目录树，可能有好几层。
#查看节点状态
#后面再加true参数表示watch临时节点。在集群中，id2可以监听在id1上创建的节点，当id1挂了，id2就会收到消息。

　　

4.2.2 增

[zk: localhost:2181(CONNECTED) 42] create -s /worker/process1/123 'i am auth process'
Created /worker/process1/1230000000003
#增加顺序子节点。类似一个名为123的进程需要很多线程。
[zk: localhost:2181(CONNECTED) 0] create -e  /worker/process1/124 ''
Created /worker/process1/124
#创建临时节点。client把一个临时节点注册到zook，client一旦失联，节点消失。

　　

4.2.3 删

[zk: localhost:2181(CONNECTED) 40] delete /worker/process1/123
#删除一节点

　　

4.2.4 查

[zk: localhost:2181(CONNECTED) 3] get /worker/process1/1250000000005
wip="60.123.44.30";lip="192.168.10.3"
cZxid = 0x600000008
ctime = Fri Apr 27 10:12:33 CST 2018
mZxid = 0x600000008
mtime = Fri Apr 27 10:12:33 CST 2018
pZxid = 0x600000008
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 37
numChildren = 0
#查一个节点的内容。可以发现dataLength = 37

　　

4.2.5 改

[zk: localhost:2181(CONNECTED) 4] set /worker/process1/1250000000005 'wip="60.123.44.30";lip="192.168.10.4"'