ZooKeeper常用命令列操作

四 ZooKeeper常用命令列操作

• 通過./zkCli.sh 開啟zk的客戶端進入命令列後臺

  • ls/ls2 列出當前節點下的子節點 ls2還會列出當前節點的狀態

  [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 與 stat命令
    • stat 列出節點狀態 ls2相當於 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 獲取節點內容和節點狀態

  [zk: localhost:2181(CONNECTED) 8] get /zookeeper
  
  cZxid = 0x0 #該節點建立（Create）時的id
  ctime = Thu Jan 01 08:00:00 CST 1970
  mZxid = 0x0 #該節點修改（Modify）後的id
  mtime = Thu Jan 01 08:00:00 CST 1970
  pZxid = 0x0 #子節點列表最後一次被修改的事務id
  cversion = -1 #子節點的版本號
  dataVersion = 0 #當前節點資料的版本號 節點資料改變時這個值會變化
  aclVersion = 0  # 許可權版本, 許可權發生變化時版本號回發生變化
  ephemeralOwner = 0x0
  dataLength = 0 #資料長度
  numChildren = 1 #子節點數量

4.2 zk特性 session的基本原理與create命令使用

• 客戶端與服務端之間的連結存在Session(會話)

• 每個會話可以設定一個超時時間

• 心跳機制: 客戶端向服務端的ping包請求

• 心跳結束, session則過期

• Session過期, 則臨時節點znode會被拋棄

• create命令

  [zk: localhost:2181(CONNECTED) 10] create /czk czk-data #建立永久節點
  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

  • 建立臨時節點 &session過期臨時節點刪除

  [zk: localhost:2181(CONNECTED) 12] create -e /itheima/tmp itheima-data
  Created /itheima/tmp
  [zk: localhost:2181(CONNECTED) 13] get /itheima
  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

  • 建立順序節點

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

4.3 set/delete 命令

• set命令:

   set path data [version] # set 路徑 資料 [版本號]       []內為可選引數

  • 不傳入版本號

  [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

  • 不傳入版本號可能會有併發修改問題 可以通過指定版本號類似加鎖功能

  [zk: localhost:2181(CONNECTED) 22] set /itheima itheima-data3 1
  version No is not valid : /itheima  #版本不匹配 修改失敗 當前版本2
  [zk: localhost:2181(CONNECTED) 23] set /itheima itheima-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 /itheima
  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 /itheima
  [sec0000000003, sec0000000001, sec0000000002]
  [zk: localhost:2181(CONNECTED) 27] delete /itheima/sec000000000
  sec0000000003   sec0000000001   sec0000000002
  [zk: localhost:2181(CONNECTED) 27] delete /itheima/sec0000000001
  [zk: localhost:2181(CONNECTED) 28] ls /itheima
  [sec0000000003, sec0000000002]
  [zk: localhost:2181(CONNECTED) 29] set /itheima/sec000000000
  sec0000000003   sec0000000002
  [zk: localhost:2181(CONNECTED) 29] set /itheima/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 /itheima/sec000000000
  sec0000000003   sec0000000002
  [zk: localhost:2181(CONNECTED) 30] delete /itheima/sec0000000002 0
  version No is not valid : /itheima/sec0000000002

• 總結 使用set / delete命令的時候儘量使用版本號 避免誤操作

4.4 watcher機制

• 針對每個節點的操作, 都會有一個監督者->watcher

• 當監控的某個物件(znode)發生了變化, 則觸發watcher事件

• zk中的watcher是一次性的, 觸發後立即銷燬

• 父節點, 子節點增刪改都能觸發其watcher

• 針對不同型別的操作, 觸發的watcher事件也不同:

  • (子)節點建立事件
  • (子)節點刪除事件
  • (子)節點資料變化事件

• watcher命令列

  • 通過get path [watch]設定watcher
  • 父節點 增 刪 改操作觸發 watcher
  • 子節點 增 刪 改操作觸發 watcher

• 建立父節點觸發: NodeCreated

  • stat path [watch]

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

  • get path [watch]

  [zk: localhost:2181(CONNECTED) 36] get /itcast 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:/itcast
  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 /itcast watch
  []
  [zk: localhost:2181(CONNECTED) 39] delete /itcast
  
  WATCHER::
  
  WatchedEvent state:SyncConnected type:NodeDeleted path:/itcast

• ls為父節點設定watcher, 建立子節點觸發:NodeChildrenChanged

• ls為父節點設定watcher, 刪除子節點觸發:NodeChildrenChanged

• ls為父節點設定watcher, 修改子節點不觸發事件

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

• watcher 使用場景

  •