原文:https://blog.csdn.net/pengweismile/article/details/115444734
作者:偉娃娃
Zookeeper是Apache Hadoop的一個子項目,它主要用來解決分佈式系統中經常遇到的一些數據管理問題,例如,統一命名,狀態同步,集羣管理,分佈式應用配置管理。
Zookeeper的定位,這個動物園的管理者,如下圖
ookeeper又2個特性
特性一 樹形結構,每個子目錄可以被增加刪除
特性二 事件監聽機制
特性一
zookeeper可以對目錄樹中的任意一個節點進行監聽。監聽是隻監聽目錄下面的目錄變化。
zookeeper類似一個文件系統,每個子目錄被稱爲目錄節點,允許我們自由的增加刪除目錄節點。
znode節點的類型:
持久化目錄節點(PERSISTENT), 創建好之後就永久存在
持久化順序編號節點(PERSISTENT_SEQUENTIAL),創建好節點後還可以默認帶個自增的編號
臨時目錄節點(EPHEMERAL),和sessionId綁定的,當客戶端被關閉之後,對於的臨時目錄節點會被刪除
歷史順序編號目錄節點(EPHEMERAL_SEQUENTIAL),臨時節點帶個自增的編號
容器節點(Container),3.5.3新增的特性,沒有子節點的容器節點會被清除掉。
TTL節點,3.5.3新增的特性,位節點設定了失效時間。具體失效時間卻決於後臺檢測失效線程的輪詢頻率。
臨時節點被刪除過程:
長連接和短連接的區別,根據自己的業務來定的。
Zookeeper的安裝
Step1:配置JAVA環境,檢驗環境:
java ‐version
Step2: 下載解壓 zookeeper
wget https://mirror.bit.edu.cn/apache/zookeeper/zookeeper‐3.5.8/apache‐zookeeper‐3.5.8‐bin.tar.gz
https://zookeeper.apache.org/releases.html#download
tar ‐zxvf apache‐zookeeper‐3.5.8‐bin.tar.gz cd apache‐zookeeper‐3.5.8‐bin
Step5: 檢測是否啓動成功
ps -ef| grep zookeeper
Step6: 連接服務器
bin/zkCli.sh ‐server ip:port
創建不同的節點
-s: 順序節點-
e: 臨時節點
-c: 容器節點
-t: 可以給節點添加過期時間,默認禁用,需要通過系統參數啓用
zoomkeeper在目錄上的增刪改查
[zk: localhost:2181(CONNECTED) 4] create /test "hello" Created /test [zk: localhost:2181(CONNECTED) 5] get /test hello [zk: localhost:2181(CONNECTED) 6] set /test "hello world" [zk: localhost:2181(CONNECTED) 7] get /test hello world [zk: localhost:2181(CONNECTED) 8] delete /test [zk: localhost:2181(CONNECTED) 9] get /test org.apache.zookeeper.KeeperException$NoNodeException: KeeperErrorCode = NoNode for /test [zk: localhost:2181(CONNECTED) 10]
ZK中沒有相對路徑一說, 所有路徑都是絕對路徑。
創建子目錄,操作
[zk: localhost:2181(CONNECTED) 10] create /test1/sub1 hello Node does not exist: /test1/sub1 [zk: localhost:2181(CONNECTED) 11] create /test1 hello1 Created /test1 [zk: localhost:2181(CONNECTED) 12] create /test1/sub1 "hello sub" Created /test1/sub1 [zk: localhost:2181(CONNECTED) 13] ls -R /test1 /test1 /test1/sub1
創建順序節點 -s
[zk: localhost:2181(CONNECTED) 22] create /seq Created /seq [zk: localhost:2181(CONNECTED) 24] create -s /seq/Allen- "hello" Created /seq/Allen-0000000001 [zk: localhost:2181(CONNECTED) 25] create -s /seq/Allen- "hello" Created /seq/Allen-0000000002 [zk: localhost:2181(CONNECTED) 26] create -s /seq/Allen- "hello" Created /seq/Allen-0000000003 [zk: localhost:2181(CONNECTED) 27] create -s /seq/Allen- "hello" Created /seq/Allen-0000000004 [zk: localhost:2181(CONNECTED) 28] create -s /seq/Allen- "hello" Created /seq/Allen-0000000005 [zk: localhost:2181(CONNECTED) 30] ls -R /seq /seq /seq/Allen-0000000001 /seq/Allen-0000000002 /seq/Allen-0000000003 /seq/Allen-0000000004 /seq/Allen-0000000005 [zk: localhost:2181(CONNECTED) 31]
創建臨時節點 -e:
[zk: localhost:2181(CONNECTED) 31] create -e /ephemeral "hello ephemeral" Created /ephemeral [zk: localhost:2181(CONNECTED) 32] get -s /ephemeral hello ephemeral cZxid = 0x15 ctime = Mon Apr 05 03:57:30 PDT 2021 mZxid = 0x15 mtime = Mon Apr 05 03:57:30 PDT 2021 pZxid = 0x15 cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x1001f373c3a0001 dataLength = 15 numChildren = 0
臨時節點與持久節點的區別在於上面節點元數據信息的ephemeraOwner的值是不一樣的。當客戶端關掉,臨時節點就沒有了。臨時節點下面是不能有子節點的。
[zk: localhost:2181(CONNECTED) 34] create -e /ephemeral/sub Ephemerals cannot have children: /ephemeral/sub [zk: localhost:2181(CONNECTED) 35]
[zk: localhost:2181(CONNECTED) 33] get -s /seq null cZxid = 0xe ctime = Mon Apr 05 03:54:16 PDT 2021 mZxid = 0xe mtime = Mon Apr 05 03:54:16 PDT 2021 pZxid = 0x14 cversion = 6 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 0 numChildren = 6 [zk: localhost:2181(CONNECTED) 34]
創建臨時順序節點 -e -s
[zk: localhost:2181(CONNECTED) 37] create -e -s /seq-eph Created /seq-eph0000000005 [zk: localhost:2181(CONNECTED) 38] create -e -s /seq-eph Created /seq-eph0000000006 [zk: localhost:2181(CONNECTED) 39] create -e -s /seq-eph
創建container節點 -c, 唯一的區別是,當刪除掉container節點下的所有子節點後, container節點本身也會被清除掉
[zk: localhost:2181(CONNECTED) 3] create -c /container Created /container [zk: localhost:2181(CONNECTED) 4] create /container/sub1 Created /container/sub1 [zk: localhost:2181(CONNECTED) 5] create /container/sub2 Created /container/sub2 [zk: localhost:2181(CONNECTED) 6] create /container/sub3 Created /container/sub3 [zk: localhost:2181(CONNECTED) 7] ls -R /container /container /container/sub1 /container/sub2 /container/sub3 [zk: localhost:2181(CONNECTED) 8] delete /container/sub1 [zk: localhost:2181(CONNECTED) 9] delete /container/sub2 [zk: localhost:2181(CONNECTED) 10] delete /container/sub3 [zk: localhost:2181(CONNECTED) 11] ls / [container, seq, seq0000000002, test1, zookeeper] [zk: localhost:2181(CONNECTED) 12] ls / [container, seq, seq0000000002, test1, zookeeper] [zk: localhost:2181(CONNECTED) 16] ls / [seq, seq0000000002, test1, zookeeper]
創建就ttl節點 -t ,ttl節點的特性是可以創建一個打失效時間的節點,失效時間過來之後節點會被自動刪除。
1. 關閉服務
[allen@localhost bin]$ ./zkServer.sh stop ../zoo.cfg /usr/bin/java ZooKeeper JMX enabled by default Using config: ../zoo.cfg Stopping zookeeper ... ./zkServer.sh: line 213: kill: (61723) - No such process STOPPED [allen@localhost bin]$
2. 添加擴展的業務,在zkServer.sh 中增加如下配置
-Dzookeeper.extendedTypesEnabled=true
3. 重新啓動服務
[allen@localhost bin]$ ./zkServer.sh start ../zoo.cfg /usr/bin/java ZooKeeper JMX enabled by default Using config: ../zoo.cfg Starting zookeeper ... STARTED [allen@localhost bin]$ vi zkServer.sh [allen@localhost bin]$ ./zkCli.sh /usr/bin/java Connecting to localhost:2181
如下, ttl-note在一段時間後自己就沒有了,不用手動刪除。
[zk: localhost:2181(CONNECTED) 0] create -t 5000 /ttl-node ttttt Created /ttl-node [zk: localhost:2181(CONNECTED) 1] ls / [seq, seq0000000002, test1, ttl-node, zookeeper] [zk: localhost:2181(CONNECTED) 2] ls / [seq, seq0000000002, test1, ttl-node, zookeeper] [zk: localhost:2181(CONNECTED) 9] ls / [seq, seq0000000002, test1, ttl-node, zookeeper] [zk: localhost:2181(CONNECTED) 10] ls / [seq, seq0000000002, test1, zookeeper] [zk: localhost:2181(CONNECTED) 11]