【ZooKeeper】ZooKeeper入门流水记

单机模式

下载zookeeper的包

wget http://mirror.bit.edu.cn/apache/zookeeper/zookeeper-3.4.9/zookeeper-3.4.9.tar.gz

解压、分解归档包

gzip -d zookeeper-3.4.9.tar.gz
tar -xf zookeeper-3.4.9.tar

修改配置文件

查看下默认的配置文件，基本符合本次测试要求。将zoo_sample.cfg拷贝为zoo.cfg：

cp zoo_sample.cfg zoo.cfg

zoo.cfg配置的简单解释：

[root@localhost bin]# cat /usr/local/zookeeper-3.4.9/conf/zoo.cfg 
# The number of milliseconds of each tick
tickTime=2000 # zk最小的单位时间，其他很多时间参数是此单位时间的n倍
# The number of ticks that the initial 
# synchronization phase can take
initLimit=10 # Leader服务器等待Follow服务器启动，完成数据同步的时间。这里配置为10表示单位时间的10倍
# The number of ticks that can pass between 
# sending a request and getting an acknowledgement
syncLimit=5 # Leader服务器与Follow服务器心跳检测的最大无响应时间
# the directory where the snapshot is stored.
# do not use /tmp for storage, /tmp here is just 
# example sakes.
dataDir=/var/zookeeper # 快照文件存储目录
# the port at which the clients will connect
clientPort=2181 # 服务端口
# 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

启动

[root@localhost bin]# sh zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper-3.4.9/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED

查看启动日志

[root@localhost bin]# less zookeeper.out 

测试是否成功

[root@localhost bin]# telnet 127.0.0.1 2181
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
stat
Zookeeper version: 3.4.9-1757313, built on 08/23/2016 06:50 GMT
Clients:
 /127.0.0.1:42587[0](queued=0,recved=1,sent=0)

Latency min/avg/max: 0/0/0
Received: 1
Sent: 0
Connections: 1
Outstanding: 0
Zxid: 0x0
Mode: standalone
Node count: 4
Connection closed by foreign host.

关闭

[root@localhost local]# sh /usr/local/zookeeper-3.4.9/bin/zkServer.sh stop
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper-3.4.9/bin/../conf/zoo.cfg
Stopping zookeeper ... STOPPED

单机模式（Windows）

如果我们在Windows下开发，最方便地是用Windows版本的ZooKeeper，安装起来非常方便。

下载

下载的版本与Linux版本一致的，并没有就不同的平台下载不同的包。
下载后就解压吧。

修改配置

在ZooKeeper的conf目录下，拷贝一份zoo_sample.cfg文件，命名为zoo.cfg，修改dataDir的值为Windows的路径格式，比如dataDir=d:/tmp/zookeeper。

启动

在ZooKeeper的bin目录下，运行zkServer.cmd即运行ZooKeeper了，默认端口为2181。

集群模式

集群模式，最少需要3个节点。

修改配置

我们沿用基础配置，在zoo.cfg后面追加各节点的地址：

server.1=192.168.1.101:2888:3888
server.2=192.168.1.102:2889:3889
server.3=192.168.1.103:2890:3890

这里的端口我都分离开来了，因为我的其中两个虚拟系统安装在同一物理机器中，为了避免冲突。

拷贝文件到其他节点

将修改好的完整的zookeeper远程拷贝到另外两个节点：

scp -r /usr/local/zookeeper-3.4.9-cluster/ root@192.168.1.102:/usr/local/
scp -r /usr/local/zookeeper-3.4.9-cluster/ root@192.168.1.103:/usr/local/

创建myid标识节点

需要在各个节点的数据目录中用一个叫myid的文件标识自己的节点ID，myid的内容只有一个ID，对照zoo.cfg的配置，这里应该分别是1、2、3。
各个节点分别执行以下3条指令（一个节点一条）：
echo "1" > /var/zookeeper/myid、echo "2" > /var/zookeeper/myid、echo "3" > /var/zookeeper/myid。

启动

sh /usr/local/zookeeper-3.4.9-cluster/bin/zkServer.sh start

测试是否成功

[root@localhost local]# telnet 127.0.0.1 2181
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
stat
Zookeeper version: 3.4.9-1757313, built on 08/23/2016 06:50 GMT
Clients:
 /127.0.0.1:46009[0](queued=0,recved=1,sent=0)

Latency min/avg/max: 0/0/0
Received: 1
Sent: 0
Connections: 1
Outstanding: 0
Zxid: 0x300000000
Mode: leader
Node count: 4
Connection closed by foreign host.

可能遇到的问题

• 端口的冲突
• 防火墙拦截了
• myid没配置或配置不正确

客户端命令

客户端连接命令

连接命令：/opt/zookeeper-3.4.9/bin/zkCli.sh -server 127.0.0.1:2181进入客户端命令行模式。

查看指定路径下的节点

[zk: 127.0.0.1:2181(CONNECTED) 0] ls /
[my-elastic-job-nn, zookeeper]

其中/zookeeper是保留的节点，而my-elastic-job-nn是我创建的节点。

查看节点的信息

[zk: 127.0.0.1:2181(CONNECTED) 7] get /my-elastic-job-nn/mySimpleJob/config 
{"jobName":"mySimpleJob","jobClass":"com.nicchagil.MySimpleJob","jobType":"SIMPLE","cron":"0/5 * * * * ?","shardingTotalCount":2,"shardingItemParameters":"0u003dX,1u003dY","jobParameter":"myParameteru003d123","failover":false,"misfire":true,"description":"","jobProperties":{"job_exception_handler":"com.dangdang.ddframe.job.executor.handler.impl.DefaultJobExceptionHandler","executor_service_handler":"com.dangdang.ddframe.job.executor.handler.impl.DefaultExecutorServiceHandler"},"monitorExecution":true,"maxTimeDiffSeconds":-1,"monitorPort":9999,"jobShardingStrategyClass":"","reconcileIntervalMinutes":-1,"disabled":false,"overwrite":true}
cZxid = 0x5
ctime = Thu Aug 03 08:25:46 PDT 2017
mZxid = 0x1a2b
mtime = Sat Aug 05 09:47:41 PDT 2017
pZxid = 0x5
cversion = 0
dataVersion = 20
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 646
numChildren = 0

输入结果的JSON是节点的内容，后面分别是节点的信息：

• cZxid，创建节点的事务ID
• ctime，创建节点的时间
• mZxid，最后更新节点的事务ID
• mtime，节点的最后更新时间
• pZxid，最后更新当前节点子节点列表的事务ID
• cversion，TODO
• dataVersion，TODO
• aclVersion，节点的ACL变更版本
• ephemeralOwner，TODO
• dataLength，节点内容的长度
• numChildren，子节点的个数

创建节点

创建一个持久节点

[zk: 127.0.0.1:2181(CONNECTED) 7] create /my-data 123456
Created /my-data

创建一个临时节点：

[zk: 127.0.0.1:2181(CONNECTED) 0] create -e /my-extemporaneous-node 123456
Created /my-extemporaneous-node
[zk: 127.0.0.1:2181(CONNECTED) 1] get /my-extemporaneous-node
123456
cZxid = 0x1a58
ctime = Sat Aug 05 10:34:35 PDT 2017
mZxid = 0x1a58
mtime = Sat Aug 05 10:34:35 PDT 2017
pZxid = 0x1a58
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x15da922d510000b
dataLength = 6
numChildren = 0

创建顺序的节点：

[zk: 127.0.0.1:2181(CONNECTED) 2] create -s /my-sequential-node 123456
Created /my-sequential-node0000000005

设置节点的值

[zk: 127.0.0.1:2181(CONNECTED) 7] set /my-data 789   
cZxid = 0x1a5c
ctime = Sat Aug 05 10:37:27 PDT 2017
mZxid = 0x1a5d
mtime = Sat Aug 05 10:37:51 PDT 2017
pZxid = 0x1a5c
cversion = 0
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 3
numChildren = 0

删除节点

[zk: 127.0.0.1:2181(CONNECTED) 4] delete /my-data

级联删除节点

如果节点有子节点，通过delete无法删除，可通过rmr删除

[zk: 127.0.0.1:2181(CONNECTED) 4] rmr /my-data