ZooKeeper常用命令行操作

ZooKeeper常用命令行操作

• 通过./zkCli.sh 打开zk的客户端进入命令行后台

  • ls/ls2 列出当前节点下的子节点 ls2还会列出当前节点的状态

  [zk: localhost:2181(CONNECTED) 5] ls2 /
  [cluster, controller_epoch, brokers, zookeeper, admin, isr_change_notification, consumers, log_dir_event_notification, latest_producer_id_block, config]
  cZxid = 0x0
  ctime = Thu Jan 01 08:00:00 CST 1970
  mZxid = 0x0
  mtime = Thu Jan 01 08:00:00 CST 1970
  pZxid = 0x4e
  cversion = 14
  dataVersion = 0
  aclVersion = 0
  ephemeralOwner = 0x0
  dataLength = 0
  numChildren = 10
  
  

  • get 与 stat命令
    • stat 列出节点状态 ls2相当于 ls + stat

  [zk: localhost:2181(CONNECTED) 6] stat /
  cZxid = 0x0
  ctime = Thu Jan 01 08:00:00 CST 1970
  mZxid = 0x0
  mtime = Thu Jan 01 08:00:00 CST 1970
  pZxid = 0x4e
  cversion = 14
  dataVersion = 0
  aclVersion = 0
  ephemeralOwner = 0x0
  dataLength = 0
  numChildren = 10
  
  

  • get命令 获取节点内容和节点状态

  [zk: localhost:2181(CONNECTED) 8] get /zookeeper
  
  cZxid = 0x0 #该节点创建（Create）时的id
  ctime = Thu Jan 01 08:00:00 CST 1970
  mZxid = 0x0 #该节点修改（Modify）后的id
  mtime = Thu Jan 01 08:00:00 CST 1970
  pZxid = 0x0 #子节点列表最后一次被修改的事务id
  cversion = -1 #子节点的版本号
  dataVersion = 0 #当前节点数据的版本号 节点数据改变时这个值会变化
  aclVersion = 0  # 权限版本, 权限发生变化时版本号回发生变化
  ephemeralOwner = 0x0
  dataLength = 0 #数据长度
  numChildren = 1 #子节点数量
  

4.2 zk特性 session的基本原理与create命令使用

• 客户端与服务端之间的链接存在Session(会话)

• 每个会话可以设置一个超时时间

• 心跳机制: 客户端向服务端的ping包请求

• 心跳结束, session则过期

• Session过期, 则临时节点znode会被抛弃

• create命令

  [zk: localhost:2181(CONNECTED) 10] create /czk czk-data #创建永久节点
  Created /czk
  [zk: localhost:2181(CONNECTED) 11] get /czk
  czk-data
  cZxid = 0x50
  ctime = Sat Dec 29 17:17:53 CST 2018
  mZxid = 0x50
  mtime = Sat Dec 29 17:17:53 CST 2018
  pZxid = 0x50
  cversion = 0
  dataVersion = 0
  aclVersion = 0
  ephemeralOwner = 0x0
  dataLength = 12
  numChildren = 0
  

  • 创建临时节点 &session过期临时节点删除

  [zk: localhost:2181(CONNECTED) 12] create -e /czk/tmp czk-data
  Created /itheima/tmp
  [zk: localhost:2181(CONNECTED) 13] get /czk
  itheima-data
  cZxid = 0x50
  ctime = Sat Dec 29 17:17:53 CST 2018
  mZxid = 0x50
  mtime = Sat Dec 29 17:17:53 CST 2018
  pZxid = 0x51
  cversion = 1
  dataVersion = 0
  aclVersion = 0
  ephemeralOwner = 0x0
  dataLength = 12
  numChildren = 1
  

  • 创建顺序节点

  [zk: localhost:2181(CONNECTED) 1] ls /czk
  []
  [zk: localhost:2181(CONNECTED) 2] create -s /czk/sec seq
  Created /itheima/sec0000000001
  [zk: localhost:2181(CONNECTED) 3] create -s /czk/sec seq
  Created /itheima/sec0000000002
  [zk: localhost:2181(CONNECTED) 4] ls /czk
  [sec0000000001, sec0000000002]
  
  

4.3 set/delete 命令

• set命令:

   set path data [version] # set 路径 数据 [版本号]       []内为可选参数
  

  • 不传入版本号

  [zk: localhost:2181(CONNECTED) 17] get /czk
  czk-data1
  cZxid = 0x5b
  ctime = Sat Dec 29 17:45:26 CST 2018
  mZxid = 0x66
  mtime = Sat Dec 29 18:00:12 CST 2018
  pZxid = 0x65
  cversion = 5
  dataVersion = 1
  aclVersion = 0
  ephemeralOwner = 0x0
  dataLength = 13
  numChildren = 3
  [zk: localhost:2181(CONNECTED) 18] set /czk czk-data2
  cZxid = 0x5b
  ctime = Sat Dec 29 17:45:26 CST 2018
  mZxid = 0x67
  mtime = Sat Dec 29 18:02:15 CST 2018
  pZxid = 0x65
  cversion = 5
  dataVersion = 2
  aclVersion = 0
  ephemeralOwner = 0x0
  dataLength = 13
  numChildren = 3
  [zk: localhost:2181(CONNECTED) 19] get /czk
  czk-data2
  cZxid = 0x5b
  ctime = Sat Dec 29 17:45:26 CST 2018
  mZxid = 0x67
  mtime = Sat Dec 29 18:02:15 CST 2018
  pZxid = 0x65
  cversion = 5
  dataVersion = 2
  aclVersion = 0
  ephemeralOwner = 0x0
  dataLength = 13
  numChildren = 3
  

  • 不传入版本号可能会有并发修改问题 可以通过指定版本号类似加锁功能

  [zk: localhost:2181(CONNECTED) 22] set /czk czk-data3 1
  version No is not valid : /czk  #版本不匹配 修改失败 当前版本2
  [zk: localhost:2181(CONNECTED) 23] set /czk czk-data3 2
  cZxid = 0x5b
  ctime = Sat Dec 29 17:45:26 CST 2018
  mZxid = 0x69
  mtime = Sat Dec 29 18:29:21 CST 2018
  pZxid = 0x65
  cversion = 5
  dataVersion = 3
  aclVersion = 0
  ephemeralOwner = 0x0
  dataLength = 13
  numChildren = 3
  [zk: localhost:2181(CONNECTED) 24] get /czk
  itheima-data3
  cZxid = 0x5b
  ctime = Sat Dec 29 17:45:26 CST 2018
  mZxid = 0x69
  mtime = Sat Dec 29 18:29:21 CST 2018
  pZxid = 0x65
  cversion = 5
  dataVersion = 3
  aclVersion = 0
  ephemeralOwner = 0x0
  dataLength = 13
  numChildren = 3
  

  • delete 命令: delete path [version]

  [zk: localhost:2181(CONNECTED) 25] ls /czk
  [sec0000000003, sec0000000001, sec0000000002]
  [zk: localhost:2181(CONNECTED) 27] delete /czk/sec000000000
  sec0000000003   sec0000000001   sec0000000002
  [zk: localhost:2181(CONNECTED) 27] delete /czk/sec0000000001
  [zk: localhost:2181(CONNECTED) 28] ls /czk
  [sec0000000003, sec0000000002]
  [zk: localhost:2181(CONNECTED) 29] set /czk/sec000000000
  sec0000000003   sec0000000002
  [zk: localhost:2181(CONNECTED) 29] set /czk/sec0000000002 test2
  cZxid = 0x64
  ctime = Sat Dec 29 17:49:38 CST 2018
  mZxid = 0x6b
  mtime = Sat Dec 29 18:54:33 CST 2018
  pZxid = 0x64
  cversion = 0
  dataVersion = 1
  aclVersion = 0
  ephemeralOwner = 0x0
  dataLength = 5
  numChildren = 0
  [zk: localhost:2181(CONNECTED) 30] delete /czk/sec000000000
  sec0000000003   sec0000000002
  [zk: localhost:2181(CONNECTED) 30] delete /czk/sec0000000002 0
  version No is not valid : /czk/sec0000000002
  

• 总结 使用set / delete命令的时候尽量使用版本号 避免误操作

4.4 watcher机制

• 针对每个节点的操作, 都会有一个监督者->watcher

• 当监控的某个对象(znode)发生了变化, 则触发watcher事件

• zk中的watcher是一次性的, 触发后立即销毁

• 父节点, 子节点增删改都能触发其watcher

• 针对不同类型的操作, 触发的watcher事件也不同:

  • (子)节点创建事件
  • (子)节点删除事件
  • (子)节点数据变化事件

• watcher命令行

  • 通过get path [watch]设置watcher
  • 父节点 增 删 改操作触发 watcher
  • 子节点 增 删 改操作触发 watcher

• 创建父节点触发: NodeCreated

  • stat path [watch]

  [zk: localhost:2181(CONNECTED) 33] stat /czk watch
  Node does not exist: /itcast
  [zk: localhost:2181(CONNECTED) 35] create /czk 123
  
  WATCHER::Created /czk
  
  
  WatchedEvent state:SyncConnected type:NodeCreated path:/czk
  
  

  • get path [watch]

  [zk: localhost:2181(CONNECTED) 36] get /czk watch
  123
  cZxid = 0x6d
  ctime = Sat Dec 29 19:43:13 CST 2018
  mZxid = 0x6d
  mtime = Sat Dec 29 19:43:13 CST 2018
  pZxid = 0x6d
  cversion = 0
  dataVersion = 0
  aclVersion = 0
  ephemeralOwner = 0x0
  dataLength = 3
  numChildren = 0
  [zk: localhost:2181(CONNECTED) 37] set /itcast 789
  
  WATCHER::
  
  WatchedEvent state:SyncConnected type:NodeDataChanged path:/czk
  cZxid = 0x6d
  ctime = Sat Dec 29 19:43:13 CST 2018
  mZxid = 0x6e
  mtime = Sat Dec 29 19:47:24 CST 2018
  pZxid = 0x6d
  cversion = 0
  dataVersion = 1
  aclVersion = 0
  ephemeralOwner = 0x0
  dataLength = 3
  numChildren = 0
  

  • ls/ls2 path [watch]

  [zk: localhost:2181(CONNECTED) 38] ls /czk watch
  []
  [zk: localhost:2181(CONNECTED) 39] delete /czk
  
  WATCHER::
  
  WatchedEvent state:SyncConnected type:NodeDeleted path:/czk
  

• ls为父节点设置watcher, 创建子节点触发:NodeChildrenChanged

• ls为父节点设置watcher, 删除子节点触发:NodeChildrenChanged

• ls为父节点设置watcher, 修改子节点不触发事件

  [zk: localhost:2181(CONNECTED) 49] ls /czk watch
  [sec0000000003, dir1, sec0000000002]
  [zk: localhost:2181(CONNECTED) 51] create /czk/dir2 123
  
  WATCHER::Created /czk/dir2
  
  
  WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/czk
  [zk: localhost:2181(CONNECTED) 52] ls /czk watch
  [sec0000000003, dir2, dir1, sec0000000002]
  [zk: localhost:2181(CONNECTED) 53] delete /czk/dir2
  
  WATCHER::
  
  WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/czk
  [zk: localhost:2181(CONNECTED) 54]