zookeeper集群原理与概述

zookeeper集群原理

zookeeper的leader选举

zookeeper服务端状态

looking: 寻找leader状态，当服务器处于该状态时，它会认为当前集群中没有leader，因此需要进入leader选举状态。

leading: 领导者状态，表明当前服务器角色时leader。

following: 跟随着状态，表明当前服务器角色时follower。

observing: 观察者状态，表明当前服务器角色时observer。

zookeeper集群启动时期的leader选举

在集群初始化节点，当有一台服务器zk101启动时，其单独无法进行和完成leader选举，当第二台服务器zk102启动时，此时两台机器就可以相互通信，每台机器都试图找到leader，于是进入leader选举过程。

zookeeper集群启动时期的leader选举过程如下所示:

每个server发出一个投票，由于初始情况，zk101和zk102都会将自己作为leader服务器来进行投票，每次投票会包含所推举的服务器myid和zxid，使用(myid,zxid)来表示，此时zk101投票为(101,0)，zk102的投票为(102,0)，然后各自将跟这个投票发给集群的其它机器;
myid: 表示当前zookeeper server的server id。
zxid: 表示zookeeper transaction id，即zookeeper事务ID。
集群中每台服务器接收来自集群中各个服务器的投票;
处理投票，针对每一个投票，服务器都需要将别人的的投票和自己的投票进行pk，pk的规则如下:
（1）优先检查zxid，zxid比较大的服务器优先作为leader;
（2）如果zxid相同，那么就比较myid，myid较大的服务器作为leader服务器;
综上所述，我们可以针对zk101和zk102选举的过程如下:
对于zk101而言，它的投票是"(101,0)"，接收zk102的投票为"(102,0)"，首先会比较两者的zxid，均为0，再比较myid，此时zk102的myid最大，于是zk101节点需要更新自己的投票为"(102,0)"。
对于zk102而言，它的投票是"(102,0)"，接收zk101的投票为"(101,0)"，很明显zk101的myid较小，因此zk102无需更新字节的投票，只是再次向集群中所有机器上发送一次投票信息即可;
统计投票，每次投票后，服务器都会统计投票信息，判断是否已经有过半机器(如果集群只有3台，那么过半就是2台服务器)接收到相同的投票信息，对于zk101和zk102而言，都统计出集群中已经有两台机器接收了(102,0)的投票信息，此时认为已经选出来leader;
改变服务器状态，一旦确定了leader，每个zookeeper服务器就会更新自己的状态，如果是follower，那么就变更为following，如果是leader，就变更为leading。

判断是否已经有过半机器接收到相同的投票信息:
假设集群可参与投票的服务器数量为N，那么过半机器数量计算方式为: (N / 2 + 1)。我们的集群只有3台，那么过半就是2台服务器。

zookeeper集群运行时期的leader选举

在zookeeper运行期间，leader与非leader服务器各司其职，即便当有非leader服务器宕机或新加入，此时也不会影响leader。

但是一旦leader服务器挂了，那么这个集群将暂停对外服务，当剩余节点数大于原集群半数节点时，则zookeeper集群可以进入新一轮leader选举，其过程和启动时期的leader选举过程基本一致。

假设正在运行的有zk101,zk102,zk103这三台服务器，当leader是zk102，若某一时刻leader挂了，此时便开始leader选举，其过程如下:

变更状态，leader挂后，余下的服务器都会将自己的服务器状态变更为looking，然后开始进入leader选举过程;
每个server会发出一个投票，在运行期间，每个服务器上的zxid可能不同，此时假定zk101的zxid为"996",zk103的zxid为"965"，在第一轮投票中，zk101和zk103都会投自己，产生投票(101,996),(103,965)，然后各自将投票发送给集群中所有机器;
接收来自各个服务器的投票，与启动时过程相同;
处理投票，与启动过程相同，此时zk101将会成为leader;
统计投票，与启动时过程相同;
改变服务器的状态，与启动时过程相同;

zookeeper原子广播协议

zookeeper集群的角色

leader(领导者): 领导者负责进行投票的发起和决议，更新系统状态。

follower(跟随者): 用于接收客户请求并向客户端返回结果，将写请求转发给leader节点。在选主过程中参与投票。

obServer(观察者): 可以接收客户端连接，将写请求转发给leader节点。这是集群的可选组件。obServer不参加投票过程，只同步leader的状态。obServer的目的是为了扩展系统，提高读取速度。

client(客户端): 向zookeeper集群发起连接请求的一方。

zab协议的工作原理(写数据流程介绍)

zab协议的全称是"Zookeeper Atomic Broadcast"(zookeeper原子广播)。zookeeper是通过zab协议来保证分布式事务的最终一致性。zab是基于广播模式工作的，通过类似两阶段提交协议的方式解决数据一致性。
如下图所示，zab其工作原理如下:

leader从客户端收到一个写请求;
leader生成一个新的事务并为这个事务生成一个唯一的ZXID;
leader将这个事务提议(propose)发送给所有的follows节点;
follower节点收到的事务请求加入到历史队列(history queue)中，并发送ack给leader;
当leader收到大多数follower(集群中半数以上节点)的ack消息后，leader会发送commit请求;
当follower收到commit请求时，从历史队列中将事务请求commit;

zookeeper集群部署

部署zookeeper服务(三台都操作)

关闭防火墙

systemctl stop firewalld
systemctl disable  firewalld
setenforce 0
vim /etc/selinux/config
SELINUX=disabled

安装JDK并配置环境变量

tar -xf jdk-8u401-linux-x64.tar.gz -C /usr/local/
cd /usr/local/
mv jdk1.8.0_401/ jdk
vim /etc/profile
JAVA_HOME=/usr/local/jdk
PATH=$JAVA_HOME/bin:$PATH
source  /etc/profile
java -version

安装zookeeper并配置环境变量

tar -xf apache-zookeeper-3.7.0-bin.tar.gz -C /usr/local/
cd /usr/local/
mv apache-zookeeper-3.7.0-bin/ zookeeper
vim /etc/profile
PATH=/usr/local/zookeeper/bin:$PATH
source /etc/profile

部署集群的时间同步服务器

yum install -y ntpdate
ntpdate ntp.aliyun.com

zookeeper集群构建

修改zookeeper的配置文件

# 三台机器拷贝复制配置文件
cd /usr/local/zookeeper/conf/
cp zoo_sample.cfg zoo.cfg

# 修改10.0.0.123节点的配置文件
egrep -v "^#|^$" /usr/local/zookeeper/conf/zoo.cfg
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/data/zookeeper
clientPort=2181
clientPortAddress=10.0.0.123
server.01=10.0.0.123:2888:3888
server.02=10.0.0.124:2888:3888
server.03=10.0.0.125:2888:3888

# 修改10.0.0.124节点的配置文件
egrep -v "^#|^$"  /usr/local/zookeeper/conf/zoo.cfg
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/data/zookeeper
clientPort=2181
clientPortAddress=10.0.0.124
server.01=10.0.0.123:2888:3888
server.02=10.0.0.124:2888:3888
server.03=10.0.0.125:2888:3888

# 修改10.0.0.125节点的配置文件
egrep -v "^#|^$" /usr/local/zookeeper/conf/zoo.cfg
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/data/zookeeper
clientPort=2181
clientPortAddress=10.0.0.125
server.01=10.0.0.123:2888:3888
server.02=10.0.0.124:2888:3888
server.03=10.0.0.125:2888:3888

# 三个节点创建数据目录
mkdir /data/zookeeper -p

配置zookeeper的堆内存配置文件

# 三个节点都配置：
vim /usr/local/zookeeper/conf/java.env
#!/bin/bash
#指定JDK的安装路径
export JAVA_HOME=/usr/local/jdk
#指定zookeeper的heap内存大小
export JVMFLAGS="-Xms256m -Xmx256m $JVMFLAGS"

创建myid文件并写入服务器编号

echo 01 > /data/zookeeper/myid
echo 02 > /data/zookeeper/myid
echo 03 > /data/zookeeper/myid

启动连接zookeeper服务

# 三个节点同时启动：
zkServer.sh start

# 查看状态：
zkServer.sh status

# 连接zookeeper集群
zkCli.sh -server 10.0.0.123:2181,10.0.0.124:2181,10.0.0.125:2181
Connecting to 10.0.0.123:2181,10.0.0.124:2181,10.0.0.125:2181
2025-07-17 12:12:10,404 [myid:] - INFO  [main:Environment@98] - Client environment:zookeeper.version=3.7.0-e3704b390a6697bfdf4b0bef79e3da7a4f6bac4b, built on 2021-03-17 09:46 UTC
2025-07-17 12:12:10,407 [myid:] - INFO  [main:Environment@98] - Client environment:host.name=iZuf62y6ofk4qtcldqm37mZ
2025-07-17 12:12:10,407 [myid:] - INFO  [main:Environment@98] - Client environment:java.version=1.8.0_401
2025-07-17 12:12:10,409 [myid:] - INFO  [main:Environment@98] - Client environment:java.vendor=Oracle Corporation
2025-07-17 12:12:10,409 [myid:] - INFO  [main:Environment@98] - Client environment:java.home=/usr/local/jdk/jre
2025-07-17 12:12:10,409 [myid:] - INFO  [main:Environment@98] - Client environment:java.class.path=/usr/local/zookeeper/bin/../zookeeper-server/target/classes:/usr/local/zookeeper/bin/../build/classes:/usr/local/zookeeper/bin/../zookeeper-server/target/lib/*.jar:/usr/local/zookeeper/bin/../build/lib/*.jar:/usr/local/zookeeper/bin/../lib/zookeeper-prometheus-metrics-3.7.0.jar:/usr/local/zookeeper/bin/../lib/zookeeper-jute-3.7.0.jar:/usr/local/zookeeper/bin/../lib/zookeeper-3.7.0.jar:/usr/local/zookeeper/bin/../lib/snappy-java-1.1.7.7.jar:/usr/local/zookeeper/bin/../lib/slf4j-log4j12-1.7.30.jar:/usr/local/zookeeper/bin/../lib/slf4j-api-1.7.30.jar:/usr/local/zookeeper/bin/../lib/simpleclient_servlet-0.9.0.jar:/usr/local/zookeeper/bin/../lib/simpleclient_hotspot-0.9.0.jar:/usr/local/zookeeper/bin/../lib/simpleclient_common-0.9.0.jar:/usr/local/zookeeper/bin/../lib/simpleclient-0.9.0.jar:/usr/local/zookeeper/bin/../lib/netty-transport-native-unix-common-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-transport-native-epoll-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-transport-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-resolver-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-handler-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-common-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-codec-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-buffer-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/metrics-core-4.1.12.1.jar:/usr/local/zookeeper/bin/../lib/log4j-1.2.17.jar:/usr/local/zookeeper/bin/../lib/jline-2.14.6.jar:/usr/local/zookeeper/bin/../lib/jetty-util-ajax-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/jetty-util-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/jetty-servlet-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/jetty-server-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/jetty-security-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/jetty-io-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/jetty-http-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/javax.servlet-api-3.1.0.jar:/usr/local/zookeeper/bin/../lib/jackson-databind-2.10.5.1.jar:/usr/local/zookeeper/bin/../lib/jackson-core-2.10.5.jar:/usr/local/zookeeper/bin/../lib/jackson-annotations-2.10.5.jar:/usr/local/zookeeper/bin/../lib/commons-cli-1.4.jar:/usr/local/zookeeper/bin/../lib/audience-annotations-0.12.0.jar:/usr/local/zookeeper/bin/../zookeeper-*.jar:/usr/local/zookeeper/bin/../zookeeper-server/src/main/resources/lib/*.jar:/usr/local/zookeeper/bin/../conf:
2025-07-17 12:12:10,409 [myid:] - INFO  [main:Environment@98] - Client environment:java.library.path=/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
2025-07-17 12:12:10,409 [myid:] - INFO  [main:Environment@98] - Client environment:java.io.tmpdir=/tmp
2025-07-17 12:12:10,409 [myid:] - INFO  [main:Environment@98] - Client environment:java.compiler=<NA>
2025-07-17 12:12:10,409 [myid:] - INFO  [main:Environment@98] - Client environment:os.name=Linux
2025-07-17 12:12:10,409 [myid:] - INFO  [main:Environment@98] - Client environment:os.arch=amd64
2025-07-17 12:12:10,409 [myid:] - INFO  [main:Environment@98] - Client environment:os.version=3.10.0-1160.119.1.el7.x86_64
2025-07-17 12:12:10,409 [myid:] - INFO  [main:Environment@98] - Client environment:user.name=root
2025-07-17 12:12:10,409 [myid:] - INFO  [main:Environment@98] - Client environment:user.home=/root
2025-07-17 12:12:10,409 [myid:] - INFO  [main:Environment@98] - Client environment:user.dir=/root
2025-07-17 12:12:10,410 [myid:] - INFO  [main:Environment@98] - Client environment:os.memory.free=237MB
2025-07-17 12:12:10,411 [myid:] - INFO  [main:Environment@98] - Client environment:os.memory.max=247MB
2025-07-17 12:12:10,411 [myid:] - INFO  [main:Environment@98] - Client environment:os.memory.total=247MB
2025-07-17 12:12:10,415 [myid:] - INFO  [main:ZooKeeper@637] - Initiating client connection, connectString=10.0.0.123:2181,10.0.0.124:2181,10.0.0.125:2181 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@768debd
2025-07-17 12:12:10,420 [myid:] - INFO  [main:X509Util@77] - Setting -D jdk.tls.rejectClientInitiatedRenegotiation=true to disable client-initiated TLS renegotiation
2025-07-17 12:12:10,424 [myid:] - INFO  [main:ClientCnxnSocket@239] - jute.maxbuffer value is 1048575 Bytes
2025-07-17 12:12:10,433 [myid:] - INFO  [main:ClientCnxn@1726] - zookeeper.request.timeout value is 0. feature enabled=false
Welcome to ZooKeeper!
2025-07-17 12:12:10,438 [myid:10.0.0.123:2181] - INFO  [main-SendThread(10.0.0.123:2181):ClientCnxn$SendThread@1171] - Opening socket connection to server iZuf62y6ofk4qtcldqm37mZ/10.0.0.123:2181.
2025-07-17 12:12:10,438 [myid:10.0.0.123:2181] - INFO  [main-SendThread(10.0.0.123:2181):ClientCnxn$SendThread@1173] - SASL config status: Will not attempt to authenticate using SASL (unknown error)
2025-07-17 12:12:10,443 [myid:10.0.0.123:2181] - INFO  [main-SendThread(10.0.0.123:2181):ClientCnxn$SendThread@1005] - Socket connection established, initiating session, client: /10.0.0.123:37814, server: iZuf62y6ofk4qtcldqm37mZ/10.0.0.123:2181
JLine support is enabled
2025-07-17 12:12:10,491 [myid:10.0.0.123:2181] - INFO  [main-SendThread(10.0.0.123:2181):ClientCnxn$SendThread@1438] - Session establishment complete on server iZuf62y6ofk4qtcldqm37mZ/10.0.0.123:2181, session id = 0x100001595aa0000, negotiated timeout = 30000

WATCHER::

WatchedEvent state:SyncConnected type:None path:null
[zk: 10.0.0.123:2181,10.0.0.124:2181,10.0.0.125:2181(CONNECTED) 0] ls /
[zookeeper]

observer角色及其配置

observer角色特点

不参与集群的leader选举;
不参与集群中写数据时的ack反馈;

修改配置文件

egrep -v "^#|^$" /usr/local/zookeeper/conf/zoo.cfg
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/data/zookeeper
clientPort=2181
clientPortAddress=10.0.0.123
server.01=10.0.0.123:2888:3888:observer
server.02=10.0.0.124:2888:3888
server.03=10.0.0.125:2888:3888

egrep -v "^#|^$" /usr/local/zookeeper/conf/zoo.cfg
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/data/zookeeper
clientPort=2181
clientPortAddress=10.0.0.124
server.01=10.0.0.123:2888:3888:observer
server.02=10.0.0.124:2888:3888
server.03=10.0.0.125:2888:3888

egrep -v "^#|^$" /usr/local/zookeeper/conf/zoo.cfg
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/data/zookeeper
clientPort=2181
clientPortAddress=10.0.0.125
server.01=10.0.0.123:2888:3888:observer
server.02=10.0.0.124:2888:3888
server.03=10.0.0.125:2888:3888

重启并连接集群

# 三个节点都需要重启
zkServer.sh restart

# 查看集群状态
zkServer.sh status

# 连接observer节点
zkCli.sh -server 10.0.0.123:2181
Connecting to 10.0.0.123:2181
2025-07-17 12:16:29,108 [myid:] - INFO  [main:Environment@98] - Client environment:zookeeper.version=3.7.0-e3704b390a6697bfdf4b0bef79e3da7a4f6bac4b, built on 2021-03-17 09:46 UTC
2025-07-17 12:16:29,111 [myid:] - INFO  [main:Environment@98] - Client environment:host.name=iZuf62y6ofk4qtcldqm37mZ
2025-07-17 12:16:29,111 [myid:] - INFO  [main:Environment@98] - Client environment:java.version=1.8.0_401
2025-07-17 12:16:29,112 [myid:] - INFO  [main:Environment@98] - Client environment:java.vendor=Oracle Corporation
2025-07-17 12:16:29,112 [myid:] - INFO  [main:Environment@98] - Client environment:java.home=/usr/local/jdk/jre
2025-07-17 12:16:29,112 [myid:] - INFO  [main:Environment@98] - Client environment:java.class.path=/usr/local/zookeeper/bin/../zookeeper-server/target/classes:/usr/local/zookeeper/bin/../build/classes:/usr/local/zookeeper/bin/../zookeeper-server/target/lib/*.jar:/usr/local/zookeeper/bin/../build/lib/*.jar:/usr/local/zookeeper/bin/../lib/zookeeper-prometheus-metrics-3.7.0.jar:/usr/local/zookeeper/bin/../lib/zookeeper-jute-3.7.0.jar:/usr/local/zookeeper/bin/../lib/zookeeper-3.7.0.jar:/usr/local/zookeeper/bin/../lib/snappy-java-1.1.7.7.jar:/usr/local/zookeeper/bin/../lib/slf4j-log4j12-1.7.30.jar:/usr/local/zookeeper/bin/../lib/slf4j-api-1.7.30.jar:/usr/local/zookeeper/bin/../lib/simpleclient_servlet-0.9.0.jar:/usr/local/zookeeper/bin/../lib/simpleclient_hotspot-0.9.0.jar:/usr/local/zookeeper/bin/../lib/simpleclient_common-0.9.0.jar:/usr/local/zookeeper/bin/../lib/simpleclient-0.9.0.jar:/usr/local/zookeeper/bin/../lib/netty-transport-native-unix-common-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-transport-native-epoll-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-transport-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-resolver-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-handler-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-common-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-codec-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/netty-buffer-4.1.59.Final.jar:/usr/local/zookeeper/bin/../lib/metrics-core-4.1.12.1.jar:/usr/local/zookeeper/bin/../lib/log4j-1.2.17.jar:/usr/local/zookeeper/bin/../lib/jline-2.14.6.jar:/usr/local/zookeeper/bin/../lib/jetty-util-ajax-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/jetty-util-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/jetty-servlet-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/jetty-server-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/jetty-security-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/jetty-io-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/jetty-http-9.4.38.v20210224.jar:/usr/local/zookeeper/bin/../lib/javax.servlet-api-3.1.0.jar:/usr/local/zookeeper/bin/../lib/jackson-databind-2.10.5.1.jar:/usr/local/zookeeper/bin/../lib/jackson-core-2.10.5.jar:/usr/local/zookeeper/bin/../lib/jackson-annotations-2.10.5.jar:/usr/local/zookeeper/bin/../lib/commons-cli-1.4.jar:/usr/local/zookeeper/bin/../lib/audience-annotations-0.12.0.jar:/usr/local/zookeeper/bin/../zookeeper-*.jar:/usr/local/zookeeper/bin/../zookeeper-server/src/main/resources/lib/*.jar:/usr/local/zookeeper/bin/../conf:
2025-07-17 12:16:29,112 [myid:] - INFO  [main:Environment@98] - Client environment:java.library.path=/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
2025-07-17 12:16:29,112 [myid:] - INFO  [main:Environment@98] - Client environment:java.io.tmpdir=/tmp
2025-07-17 12:16:29,112 [myid:] - INFO  [main:Environment@98] - Client environment:java.compiler=<NA>
2025-07-17 12:16:29,112 [myid:] - INFO  [main:Environment@98] - Client environment:os.name=Linux
2025-07-17 12:16:29,112 [myid:] - INFO  [main:Environment@98] - Client environment:os.arch=amd64
2025-07-17 12:16:29,113 [myid:] - INFO  [main:Environment@98] - Client environment:os.version=3.10.0-1160.119.1.el7.x86_64
2025-07-17 12:16:29,113 [myid:] - INFO  [main:Environment@98] - Client environment:user.name=root
2025-07-17 12:16:29,113 [myid:] - INFO  [main:Environment@98] - Client environment:user.home=/root
2025-07-17 12:16:29,113 [myid:] - INFO  [main:Environment@98] - Client environment:user.dir=/root
2025-07-17 12:16:29,113 [myid:] - INFO  [main:Environment@98] - Client environment:os.memory.free=237MB
2025-07-17 12:16:29,114 [myid:] - INFO  [main:Environment@98] - Client environment:os.memory.max=247MB
2025-07-17 12:16:29,114 [myid:] - INFO  [main:Environment@98] - Client environment:os.memory.total=247MB
2025-07-17 12:16:29,117 [myid:] - INFO  [main:ZooKeeper@637] - Initiating client connection, connectString=10.0.0.123:2181 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@768debd
2025-07-17 12:16:29,121 [myid:] - INFO  [main:X509Util@77] - Setting -D jdk.tls.rejectClientInitiatedRenegotiation=true to disable client-initiated TLS renegotiation
2025-07-17 12:16:29,125 [myid:] - INFO  [main:ClientCnxnSocket@239] - jute.maxbuffer value is 1048575 Bytes
2025-07-17 12:16:29,133 [myid:] - INFO  [main:ClientCnxn@1726] - zookeeper.request.timeout value is 0. feature enabled=false
2025-07-17 12:16:29,139 [myid:10.0.0.123:2181] - INFO  [main-SendThread(10.0.0.123:2181):ClientCnxn$SendThread@1171] - Opening socket connection to server iZuf62y6ofk4qtcldqm37mZ/10.0.0.123:2181.
2025-07-17 12:16:29,139 [myid:10.0.0.123:2181] - INFO  [main-SendThread(10.0.0.123:2181):ClientCnxn$SendThread@1173] - SASL config status: Will not attempt to authenticate using SASL (unknown error)
Welcome to ZooKeeper!
2025-07-17 12:16:29,143 [myid:10.0.0.123:2181] - INFO  [main-SendThread(10.0.0.123:2181):ClientCnxn$SendThread@1005] - Socket connection established, initiating session, client: /10.0.0.123:37874, server: iZuf62y6ofk4qtcldqm37mZ/10.0.0.123:2181
JLine support is enabled
2025-07-17 12:16:29,181 [myid:10.0.0.123:2181] - INFO  [main-SendThread(10.0.0.123:2181):ClientCnxn$SendThread@1438] - Session establishment complete on server iZuf62y6ofk4qtcldqm37mZ/10.0.0.123:2181, session id = 0x10000462ce80000, negotiated timeout = 30000

WATCHER::

WatchedEvent state:SyncConnected type:None path:null
[zk: 10.0.0.123:2181(CONNECTED) 0] ls /
[zookeeper]

如上所示，我们可以连接观察者(observer)节点并写入数据，但我们要知道真正负责写入的是leader节点，写请求被observer转发给leader节点了。

posted @ 2025-08-03 15:29 阿峰博客站阅读(9) 评论(0) 收藏举报

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