ZooKeeper常用命令行操作

时间：2021-07-18 17:05:41

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]

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