Zookeeper学习（3）：基本操作

一、单节点操作

1. 启动服务器和client：

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启动服务器 ~# zkServer.sh start ZooKeeper JMX enabled by default Using config: /data/zookeeper/bin/../conf/zoo.cfg Starting zookeeper ... STARTED 启动客户端 ~# zkCli.sh

2. 查看当前所有节点

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[zk: localhost:2181(CONNECTED) 0] ls -R /<br># Zookeeper系统自带的节点 / /zookeeper /zookeeper/config /zookeeper/quota

3. 新建app1和app2的znode

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[zk: localhost:2181(CONNECTED) 1] create /app1 [zk: localhost:2181(CONNECTED) 1] create /app2 [zk: localhost:2181(CONNECTED) 1] create /app1/p_1 [zk: localhost:2181(CONNECTED) 1] create /app1/p_2 [zk: localhost:2181(CONNECTED) 1] create /app1/p_3   # 查看一下 [zk: localhost:2181(CONNECTED) 0] ls -R / / /app1 /app2 /zookeeper /app1/p_1 /app1/p_2 /app1/p_3 /zookeeper/config /zookeeper/quota

 

二、实现一个分布式锁

分布式锁要求如果锁的持有者宕了，锁可以被释放。ZooKeeper 的 ephemeral 节点恰好具备这样的特性。

 客户端1：创建一个临时znode（获取锁）

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1 2	[zk: localhost:2181(CONNECTED) 6] create -e /lock Created /lock

客户端2：这个时候也去创建一个相同znode（由于被锁定了，客户端2无法获取）

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# 创建提示已经存在 [zk: localhost:2181(CONNECTED) 0] create -e /lock Node already exists: /lock   # 监控该znode [zk: localhost:2181(CONNECTED) 2] stat -w /lock cZxid = 0xb ctime = Thu May 19 09:13:48 EDT 2022 mZxid = 0xb mtime = Thu May 19 09:13:48 EDT 2022 pZxid = 0xb cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x1074e5aa8bc0000 dataLength = 0 numChildren = 0

客户端1：退出客户端，由于是临时znode，断开链接之后会自动删除（释放锁）

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[zk: localhost:2181(CONNECTED) 7] quit   WATCHER::   WatchedEvent state:Closed type:None path:null 2022-05-19 09:21:01,264 [myid:] - INFO  [main:ZooKeeper@1619] - Session: 0x1074e5aa8bc0000 closed 2022-05-19 09:21:01,266 [myid:] - ERROR [main:ServiceUtils@42] - Exiting JVM with code 0 2022-05-19 09:21:01,267 [myid:] - INFO  [main-EventThread:ClientCnxn$EventThread@578] - EventThread shut down for session: 0x1074e5aa8bc0000

客户端2：由于客户端2有监控这个znode，所以客户端1退出的时候，会收到日志，这个时候客户端2就可以创建了（获取锁）

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WATCHER::   WatchedEvent state:SyncConnected type:NodeDeleted path:/lock   # 创建znode [zk: localhost:2181(CONNECTED) 0] create -e /lock Created /lock

　　

三、3节点quorum模式Zookeeper集群搭建 

节点1：

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# 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=/data/zookeeper/data1 # 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   ## Metrics Providers # # https://prometheus.io Metrics Exporter #metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider #metricsProvider.httpPort=7000 #metricsProvider.exportJvmInfo=true   server.1=127.0.0.1:3333:3334 server.2=127.0.0.1:4444:4445 server.3=127.0.0.1:5555:5556

节点2：

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# 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.存储位置需要修改 dataDir=/data/zookeeper/data2 # the port at which the clients will connect，端口修改下 clientPort=2182 # 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   ## Metrics Providers # # https://prometheus.io Metrics Exporter #metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider #metricsProvider.httpPort=7000 #metricsProvider.exportJvmInfo=true   server.1=127.0.0.1:3333:3334 server.2=127.0.0.1:4444:4445 server.3=127.0.0.1:5555:5556

节点3：

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# 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.存储位置需要修改 dataDir=/data/zookeeper/data3 # the port at which the clients will connect，端口修改下 clientPort=2183 # 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   ## Metrics Providers # # https://prometheus.io Metrics Exporter #metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider #metricsProvider.httpPort=7000 #metricsProvider.exportJvmInfo=true   server.1=127.0.0.1:3333:3334 server.2=127.0.0.1:4444:4445 server.3=127.0.0.1:5555:5556

启动集群：

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zkServer.sh /data/zookeeper/conf/zoo-quorum-node1.cfg zkServer.sh /data/zookeeper/conf/zoo-quorum-node2.cfg zkServer.sh /data/zookeeper/conf/zoo-quorum-node3.cfg

连接集群：

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1	zkCli.sh -server 127.0.0.1:2181,127.0.0.1:2182,127.0.0.1:2183