Zookeeper常用节点命令
1 新增节点
create [-s] [-e] path data #其中-s 为有序节点，-e 临时节点
创建持久化节点并写入数据：
[zk: localhost:2181(CONNECTED) 0] create /hadoop "123456" Created /hadoop [zk: localhost:2181(CONNECTED) 1] get /hadoop 123456 cZxid = 0x2 ctime = Sat Apr 11 19:15:47 CST 2020 mZxid = 0x2 mtime = Sat Apr 11 19:15:47 CST 2020 pZxid = 0x2 cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 6 numChildren = 0
退出客户端在查看，是否能查到：
[zk: localhost:2181(CONNECTED) 3] quit Quitting... 2020-04-11 19:29:52,410 [myid:] - INFO [main:[email protected]] - Session: 0x17168d c8c420000 closed 2020-04-11 19:29:52,412 [myid:] - INFO [main-EventThread:ClientCnxn$EventThread @519] - EventThread shut down for session: 0x17168dc8c420000 [root@iZ1la3d1xbmukrZ bin]# ./zkCli.sh Connecting to localhost:2181 2020-04-11 19:29:54,955 [myid:] - INFO [main:[email protected]] - Client environm ent:zookeeper.version=3.4.10-39d3a4f269333c922ed3db283be479f9deacaa0f, built on 03/23/2017 10:13 GMT 2020-04-11 19:29:54,958 [myid:] - INFO [main:[email protected]] - Client environm ent:host.name=iZ1la3d1xbmukrZ 2020-04-11 19:29:54,958 [myid:] - INFO [main:[email protected]] - Client environm ent:java.version=1.8.0_131 2020-04-11 19:29:54,960 [myid:] - INFO [main:[email protected]] - Client environm ent:java.vendor=Oracle Corporation 2020-04-11 19:29:54,961 [myid:] - INFO [main:[email protected]] - Client environm ent:java.home=/home/zookeeper/jdk1.8.0_131/jre 2020-04-11 19:29:54,961 [myid:] - INFO [main:[email protected]] - Client environm
[zk: localhost:2181(CONNECTED) 0] get /hadoop 123456 cZxid = 0x2 ctime = Sat Apr 11 19:15:47 CST 2020 mZxid = 0x2 mtime = Sat Apr 11 19:15:47 CST 2020 pZxid = 0x2 cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 6 numChildren = 0
创建持久化有序节点，此时创建的节点名为指定节点名 + 自增序号:
[zk: localhost:2181(CONNECTED) 1] create -s /a "a" Created /a0000000001 [zk: localhost:2181(CONNECTED) 2] get /a0000000001 a cZxid = 0x5 ctime = Sat Apr 11 19:35:03 CST 2020 mZxid = 0x5 mtime = Sat Apr 11 19:35:03 CST 2020 pZxid = 0x5 cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 1 numChildren = 0 [zk: localhost:2181(CONNECTED) 3] create -s /b "b" Created /b0000000002
创建临时节点，临时节点会在会话过期后被删除：
Created /b0000000002 [zk: localhost:2181(CONNECTED) 4] create -e /tmp "tmp" Created /tmp [zk: localhost:2181(CONNECTED) 5] quit Quitting... 2020-04-11 20:25:24,342 [myid:] - INFO [main:[email protected]] - Session: 0x17168dc8c420001 closed 2020-04-11 20:25:24,344 [myid:] - INFO [main-EventThread:ClientCnxn$EventThread@519] - EventThread shut down for session: 0x17168dc8c420001 [root@iZ1la3d1xbmukrZ bin]# ./zkCli.sh WATCHER:: WatchedEvent state:SyncConnected type:None path:null [zk: localhost:2181(CONNECTED) 0] get /tmp Node does not exist: /tmp [zk: localhost:2181(CONNECTED) 1]
创建临时有序节点，临时节点会在会话过期后被删除：
[zk: localhost:2181(CONNECTED) 2] create -s -e /aa 'aaa' Created /aa0000000004 [zk: localhost:2181(CONNECTED) 3] create -s -e /bb 'nnn' Created /bb0000000005 [zk: localhost:2181(CONNECTED) 4]
2 更新节点
更新节点的命令是 set ，可以直接进行修改，如下：
[zk: localhost:2181(CONNECTED) 4] get /hadoop 123456 cZxid = 0x2 ctime = Sat Apr 11 19:15:47 CST 2020 mZxid = 0x2 mtime = Sat Apr 11 19:15:47 CST 2020 pZxid = 0x2 cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 6 numChildren = 0 [zk: localhost:2181(CONNECTED) 5] set /hadoop "3456" cZxid = 0x2 ctime = Sat Apr 11 19:15:47 CST 2020 mZxid = 0xc mtime = Sat Apr 11 20:27:51 CST 2020 pZxid = 0x2 cversion = 0 dataVersion = 1 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 4 numChildren = 0 [zk: localhost:2181(CONNECTED) 6] get /hadoop 3456 cZxid = 0x2 ctime = Sat Apr 11 19:15:47 CST 2020 mZxid = 0xc mtime = Sat Apr 11 20:27:51 CST 2020 pZxid = 0x2 cversion = 0 dataVersion = 1 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 4 numChildren = 0 [zk: localhost:2181(CONNECTED) 7]
可以基于版本号进行更改，此时类似于乐观锁机制，当你传入的数据版本号(dataVersion) 和当前节点的数据版本号不符合时，zookeeper 会拒绝本次修改：
[zk: localhost:2181(CONNECTED) 7] set /hadoop "345" 1 cZxid = 0x2 ctime = Sat Apr 11 19:15:47 CST 2020 mZxid = 0xd mtime = Sat Apr 11 20:29:15 CST 2020 pZxid = 0x2 cversion = 0 dataVersion = 2 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 3 numChildren = 0 [zk: localhost:2181(CONNECTED) 8] set /hadoop "345" 3 version No is not valid : /hadoop [zk: localhost:2181(CONNECTED) 9]
3 删除节点
删除节点的语法如下：
delete path [version]
和更新节点数据一样，也可以传入版本号，当你传入的数据版本号 (dataVersion)，当前节点的数据版本号不符合时，zookeeper 不会执行删除操作。
[zk: localhost:2181(CONNECTED) 9] delete /hadoop 3 version No is not valid : /hadoop [zk: localhost:2181(CONNECTED) 10] delete /hadoop 2 [zk: localhost:2181(CONNECTED) 11] get /hadoop Node does not exist: /hadoop [zk: localhost:2181(CONNECTED) 12]
要想删除某个节点及其所有后代节点，可以使用递归删除，命令为 rmr
[zk: localhost:2181(CONNECTED) 2] create /tmp "123" Created /tmp [zk: localhost:2181(CONNECTED) 3] create /tmp/wgr "123" Created /tmp/wgr [zk: localhost:2181(CONNECTED) 4] create /tmp/wgr/qwer "123" Created /tmp/wgr/qwer [zk: localhost:2181(CONNECTED) 5] create /tmp/wgr/qwer/re "123" Created /tmp/wgr/qwer/re [zk: localhost:2181(CONNECTED) 6] delete /tmp Node not empty: /tmp [zk: localhost:2181(CONNECTED) 7] get /tmp 123 cZxid = 0x15 ctime = Sat Apr 11 20:32:16 CST 2020 mZxid = 0x15 mtime = Sat Apr 11 20:32:16 CST 2020 pZxid = 0x16 cversion = 1 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 3 numChildren = 1 [zk: localhost:2181(CONNECTED) 8] [zk: localhost:2181(CONNECTED) 8] rmr /tmp [zk: localhost:2181(CONNECTED) 9] get /tmp Node does not exist: /tmp [zk: localhost:2181(CONNECTED) 10]
查看节点
get path
[zk: localhost:2181(CONNECTED) 6] get /hadoop 3456 cZxid = 0x2 ctime = Sat Apr 11 19:15:47 CST 2020 mZxid = 0xc mtime = Sat Apr 11 20:27:51 CST 2020 pZxid = 0x2 cversion = 0 dataVersion = 1 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 4 numChildren = 0
节点各个属性如下表。其中一个重要的概念是 Zxid(ZooKeeper TransactionId)，ZooKeeper 节点的每一次更改都具有唯一的 Zxid，如果 Zxid1 小于 Zxid2，则Zxid1 的更改发生在 Zxid2 更改之前。
| 状态属性 | 说明 |
| cZxid | 数据节点创建时的事务 ID |
| ctime | 数据节点创建时的时间 |
| mZxid | 数据节点最后一次更新时的事务 ID |
| mtime | 数据节点最后一次更新时的时间 |
| pZxid | 数据节点的子节点最后一次被修改时的事务 ID |
| cversion | 子节点的更改次数 |
| dataVersion | 节点数据的更改次数 |
| aclVersion | 节点的 ACL 的更改次数 |
| ephemeralOwner | 如果节点是临时节点， 则表示创建该节点的会话的 SessionID； 如果节点是持久节点， 则该属性值为 0 |
| dataLength | 数据内容的长度 |
| numChildren | 数据节点当前的子节点个数 |
当创建子节点的时候，pZxid会发生改变
查看节点状态
可以使用 stat 命令查看节点状态， 它的返回值和 get 命令类似， 但不会返回节点数据
[zk: localhost:2181(CONNECTED) 11] stat /hadoop cZxid = 0x1e ctime = Sat Apr 11 20:39:10 CST 2020 mZxid = 0x1e mtime = Sat Apr 11 20:39:10 CST 2020 pZxid = 0x1e cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 3 numChildren = 0 [zk: localhost:2181(CONNECTED) 12]
查看节点列表
查看节点列表有 ls path 和 ls2 path 两个命令，后者是前者的增强，不仅可以查看指定路径下的所有节点，还可以查看当前节点的信息
[zk: localhost:2181(CONNECTED) 12] ls / [b0000000002, a0000000001, hadoop, zookeeper, tmp0000000006] [zk: localhost:2181(CONNECTED) 13] ls2 / [b0000000002, a0000000001, hadoop, zookeeper, tmp0000000006] cZxid = 0x0 ctime = Thu Jan 01 08:00:00 CST 1970 mZxid = 0x0 mtime = Thu Jan 01 08:00:00 CST 1970 pZxid = 0x1e cversion = 13 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 0 numChildren = 5 [zk: localhost:2181(CONNECTED) 14]
4 监听器
get path [watch]
使用 get path [watch] 注册的监听器能够在节点内容发生改变的时候，向客户端发出通知。需要注意的是 zookeeper 的触发器是一次性的 (One-time trigger)，即触发一次后就会立即失效。
[zk: localhost:2181(CONNECTED) 18] get /hadoop watch 456 cZxid = 0x1e ctime = Sat Apr 11 20:39:10 CST 2020 mZxid = 0x1f mtime = Sat Apr 11 20:46:15 CST 2020 pZxid = 0x20 cversion = 1 dataVersion = 1 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 3 numChildren = 1 [zk: localhost:2181(CONNECTED) 19] set /hadoop 45678 WATCHER:: WatchedEvent state:SyncConnected type:NodeDataChanged path:/hadoop cZxid = 0x1e ctime = Sat Apr 11 20:39:10 CST 2020 mZxid = 0x21 mtime = Sat Apr 11 20:53:32 CST 2020 pZxid = 0x20 cversion = 1 dataVersion = 2 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 5 numChildren = 1 [zk: localhost:2181(CONNECTED) 20] set /hadoop 43 cZxid = 0x1e ctime = Sat Apr 11 20:39:10 CST 2020 mZxid = 0x22 mtime = Sat Apr 11 20:53:46 CST 2020 pZxid = 0x20 cversion = 1 dataVersion = 3 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 2 numChildren = 1 [zk: localhost:2181(CONNECTED) 21]
监听器stat path [watch]
使用 stat path [watch] 注册的监听器能够在节点状态发生改变的时候，向客户端发出通知
[zk: localhost:2181(CONNECTED) 0] stat /hadoop watch cZxid = 0x1e ctime = Sat Apr 11 20:39:10 CST 2020 mZxid = 0x22 mtime = Sat Apr 11 20:53:46 CST 2020 pZxid = 0x20 cversion = 1 dataVersion = 3 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 2 numChildren = 1 [zk: localhost:2181(CONNECTED) 1] set /hadoop 112233 WATCHER:: WatchedEvent state:SyncConnected type:NodeDataChanged path:/hadoop cZxid = 0x1e ctime = Sat Apr 11 20:39:10 CST 2020 mZxid = 0x26 mtime = Sat Apr 11 20:56:48 CST 2020 pZxid = 0x20 cversion = 1 dataVersion = 4 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 6 numChildren = 1
监听器ls\ls2 path [watch]
使用 ls path [watch] 或 ls2 path [watch] 注册的监听器能够监听该节点下所有子节点的增加和删除操作。
[zk: localhost:2181(CONNECTED) 3] ls /hadoop watch [hbase] [zk: localhost:2181(CONNECTED) 4] create /hadoop/node3 "node3" WATCHER:: Created /hadoop/node3 WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/hadoop [zk: localhost:2181(CONNECTED) 5] ls /hadoop watch [node3, hbase] [zk: localhost:2181(CONNECTED) 6] delete /hadoop/node3 WATCHER:: [zk: localhost:2181(CONNECTED) 7] WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/hadoop [zk: localhost:2181(CONNECTED) 7]