安裝Zookeeper
https://blog.csdn.net/greenplum_xiaofan/article/details/99020516#31_Zookeeper_40
1、ZK的數據模型
1） 樹形結構： /
2) ZK中的每個節點：znode，唯一的路徑標識
a) 每個znode都有自己的版本號
b） znode信息發生變化，那麼version+1
c） znode數據量不要太大，幾K就差不多了，都是存一些配置信息
d） 權限
e) Watcher
3） znode有兩種類型
a）臨時：當前session有效，不能有子節點的。
b）永久：不依賴於session
4） znode的四種形式
PERSISTENT
PERSISTENT_SEQUENTIAL 帶順序編號的
EPHEMERAL
EPHEMERAL_SEQUENTIA
ZK節點數：奇數個(>=3)
選舉：leader+flower
ZK集羣的寫操作，leader負責，會把通知所有節點寫入操作
只有收到半數以上節點的成功反饋，纔算成功
2、基本操作
啓動ZK
[hadoop@vm01 bin]$ ./zkServer.sh start
查看ZK狀態，單節點就是standalone，集羣是leader，flower
[hadoop@vm01 bin]$ ./zkServer.sh status
打開ZK客戶端
[hadoop@vm01 bin]$ ./zkCli.sh
[zk: localhost:2181(CONNECTED) 11] quit
[zk: localhost:2181(CONNECTED) 0] ls /
[zookeeper, kafka]
ls2 可以理解爲 ls+stat
[zk: localhost:2181(CONNECTED) 1] ls2 /
[zookeeper, kafka] #下面是ZK的狀態信息
cZxid = 0x0
ctime = Wed Dec 31 16:00:00 PST 1969
mZxid = 0x0
mtime = Wed Dec 31 16:00:00 PST 1969
pZxid = 0x2
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 0
numChildren = 2
顯示當前狀態信息,
[zk: localhost:2181(CONNECTED) 2] stat /
cZxid = 0x0
ctime = Wed Dec 31 16:00:00 PST 1969
mZxid = 0x0
mtime = Wed Dec 31 16:00:00 PST 1969
pZxid = 0x2
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 0
numChildren = 2
獲取
[zk: localhost:2181(CONNECTED) 3] get /zookeeper
cZxid = 0x0 #zk當前的id
ctime = Wed Dec 31 16:00:00 PST 1969
mZxid = 0x0 #修改後的id
mtime = Wed Dec 31 16:00:00 PST 1969
pZxid = 0x0 #最後跟新的子節點id
cversion = -1 #子節點版本號
dataVersion = 0 #數據版本
aclVersion = 0 #權限版本
ephemeralOwner = 0x0 #是否是臨時的
dataLength = 0 #數據長度
numChildren = 1 #有幾個孩子
create
[-s] #帶不帶編號
[-e] #臨時
[zk: localhost:2181(CONNECTED) 4] create /ruoze ruoze-data
Created /ruoze
[zk: localhost:2181(CONNECTED) 5] ls /
[ruoze, zookeeper, kafka]
[zk: localhost:2181(CONNECTED) 6] get /ruoze
ruoze-data #數據
cZxid = 0xe7
ctime = Thu Aug 15 06:16:21 PDT 2019
mZxid = 0xe7
mtime = Thu Aug 15 06:16:21 PDT 2019
pZxid = 0xe7
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 10
numChildren = 0
[zk: localhost:2181(CONNECTED) 7] create -e /ruoze/xiaoruoze xiaoruoze
Created /ruoze/xiaoruoze
[zk: localhost:2181(CONNECTED) 8] get /ruoze
ruoze-data
cZxid = 0xe7
ctime = Thu Aug 15 06:16:21 PDT 2019
mZxid = 0xe7
mtime = Thu Aug 15 06:16:21 PDT 2019
pZxid = 0xe8
cversion = 1
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 10
numChildren = 1 #有一個孩子了
[zk: localhost:2181(CONNECTED) 9] get /ruoze/xiaoruoze
xiaoruoze
cZxid = 0xe8
ctime = Thu Aug 15 06:18:09 PDT 2019
mZxid = 0xe8
mtime = Thu Aug 15 06:18:09 PDT 2019
pZxid = 0xe8
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x16c88e4a0770001 #表示是臨時節點
dataLength = 9
numChildren = 0
[zk: localhost:2181(CONNECTED) 10] quit
[hadoop@vm01 bin]$ ./zkCli.sh
[zk: localhost:2181(CONNECTED) 0] ls /ruoze
[] #發現沒有子節點了，這就是臨時的特點,退出就沒了
加編號，順序
分佈式鎖的一個實現，會藉助這個
[zk: localhost:2181(CONNECTED) 1] create -s /ruoze/seq seq
Created /ruoze/seq0000000001
[zk: localhost:2181(CONNECTED) 2] create -s /ruoze/seq seq
Created /ruoze/seq0000000002
[zk: localhost:2181(CONNECTED) 3] create -s /ruoze/seq seq
Created /ruoze/seq0000000003
[zk: localhost:2181(CONNECTED) 4] create -s /ruoze/seq seq
Created /ruoze/seq0000000004
[zk: localhost:2181(CONNECTED) 5] create -s /ruoze/seq seq
Created /ruoze/seq0000000005
[zk: localhost:2181(CONNECTED) 6]
[zk: localhost:2181(CONNECTED) 6] ls /ruoze
[seq0000000005, seq0000000003, seq0000000004, seq0000000001, seq0000000002]
修改數據，查看版本信息
[zk: localhost:2181(CONNECTED) 7] get /ruoze
ruoze-data
cZxid = 0xe7
ctime = Thu Aug 15 06:16:21 PDT 2019
mZxid = 0xe7
mtime = Thu Aug 15 06:16:21 PDT 2019
pZxid = 0xef
cversion = 7
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 10
numChildren = 5
[zk: localhost:2181(CONNECTED) 8] set /ruoze www.ruozedata.com
cZxid = 0xe7
ctime = Thu Aug 15 06:16:21 PDT 2019
mZxid = 0xf0
mtime = Thu Aug 15 06:24:30 PDT 2019
pZxid = 0xef
cversion = 7
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 17
numChildren = 5
[zk: localhost:2181(CONNECTED) 9] get /ruoze
www.ruozedata.com
cZxid = 0xe7
ctime = Thu Aug 15 06:16:21 PDT 2019
mZxid = 0xf0
mtime = Thu Aug 15 06:24:30 PDT 2019
pZxid = 0xef
cversion = 7
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 17
numChildren = 5
刪除
[zk: localhost:2181(CONNECTED) 11] delete /ruoze/seq0000000001
[zk: localhost:2181(CONNECTED) 12] ls /ruoze
[seq0000000005, seq0000000003, seq0000000004, seq0000000002]
修改seq2的數據，然後刪除，帶版本的，0的版本是刪除不掉的，
因爲修改之後版本+1，必須用最新的版本號才能刪除
set，delete都可以帶上版本號，建議帶上版本號，相當於加了一個樂觀鎖
[zk: localhost:2181(CONNECTED) 14] set /ruoze/seq0000000002 seq2
[zk: localhost:2181(CONNECTED) 16] delete /ruoze/seq0000000002 0
version No is not valid : /ruoze/seq0000000002
[zk: localhost:2181(CONNECTED) 17] delete /ruoze/seq0000000002 1
3、ZK四字命令
[hadoop@vm01 bin]$ echo stat |nc localhost 2181
Zookeeper version: 3.4.5-cdh5.7.0--1, built on 03/23/2016 18:31 GMT
Clients:
/0:0:0:0:0:0:0:1:50179[0](queued=0,recved=1,sent=0)
Latency min/avg/max: 0/0/11
Received: 229
Sent: 228
Connections: 1 #有多少連接數
Outstanding: 0
Zxid: 0xf7
Mode: standalone
Node count: 146 #節點數量
[hadoop@vm01 bin]$ echo ruok |nc localhost 2181
imok
[hadoop@vm01 bin]$ echo dump |nc localhost 2181
SessionTracker dump:
Session Sets (0):
ephemeral nodes dump:
Sessions with Ephemerals (0): #臨時節點有多少個
可以看到ZK的配置
[hadoop@vm01 bin]$ echo conf |nc localhost 2181
clientPort=2181
dataDir=/home/hadoop/app/zookeeper-3.4.5-cdh5.7.0/data/version-2
dataLogDir=/home/hadoop/app/zookeeper-3.4.5-cdh5.7.0/dataLog/version-2
tickTime=2000
maxClientCnxns=60
minSessionTimeout=4000
maxSessionTimeout=40000
serverId=0
[hadoop@vm01 bin]$ echo cons |nc localhost 2181
/0:0:0:0:0:0:0:1:50187[0](queued=0,recved=1,sent=0)
監控
[hadoop@vm01 bin]$ echo mntr |nc localhost 2181
zk_version 3.4.5-cdh5.7.0--1, built on 03/23/2016 18:31 GMT
zk_avg_latency 0
zk_max_latency 11
zk_min_latency 0
zk_packets_received 234
zk_packets_sent 233
zk_num_alive_connections 1
zk_outstanding_requests 0
zk_server_state standalone
zk_znode_count 146
zk_watch_count 0
zk_ephemerals_count 0
zk_approximate_data_size 11597
zk_open_file_descriptor_count 28
zk_max_file_descriptor_count 65536
查看有多少watcher
[zk: localhost:2181(CONNECTED) 1] get /ruoze watch #加一把鎖
[hadoop@vm01 bin]$ echo wchs |nc localhost 2181
1 connections watching 1 paths
Total watches:1 #數量1個