Kafka 集群中有一個(gè) broker 會(huì)被選舉為 Controller，負(fù)責(zé)管理集群 broker 的上下線，所有 topic 的分區(qū)副本分配和 leader 選舉等工作。

?Controller 的管理工作都是依賴于 Zookeeper 的。?
?以下為 partition 的 leader 選舉過(guò)程：?

? ? ? ??Leader選舉流程

我們?cè)囋嚠?dāng)這個(gè)主節(jié)點(diǎn)掛了，誰(shuí)會(huì)被搶到（目前這個(gè)brokers/ids/? ? 有0? 1? 2三個(gè)節(jié)點(diǎn)）

?我們啟動(dòng)zk客戶端

[root@backup01 bin]# ./zkCli.sh Connecting to localhost:2181 2020-04-19 16:05:13,799 [myid:] - INFO [main:Environment@100] - Client environment:zookeeper.version=3.4.13-2d71af4dbe22557fda74f9a9b4309b15a7487f03, built on 06/29/2018 04:05 GMT 2020-04-19 16:05:13,815 [myid:] - INFO [main:Environment@100] - Client environment:host.name=backup01 2020-04-19 16:05:13,815 [myid:] - INFO [main:Environment@100] - Client environment:java.version=1.8.0_172 2020-04-19 16:05:13,817 [myid:] - INFO [main:Environment@100] - Client environment:java.vendor=Oracle Corporation 2020-04-19 16:05:13,817 [myid:] - INFO [main:Environment@100] - Client environment:java.home=/usr/local/java/jdk1.8.0_172/jre 2020-04-19 16:05:13,817 [myid:] - INFO [main:Environment@100] - Client environment:java.class.path=/usr/local/hadoop/zookeeper/zookeeper-3.4.13/bin/../build/classes:/usr/local/hadoop/zookeeper/zookeeper-3.4.13/bin/../build/lib/*.jar:/usr/local/hadoop/zookeeper/zookeeper-3.4.13/bin/../lib/slf4j-log4j12-1.7.25.jar:/usr/local/hadoop/zookeeper/zookeeper-3.4.13/bin/../lib/slf4j-api-1.7.25.jar:/usr/local/hadoop/zookeeper/zookeeper-3.4.13/bin/../lib/netty-3.10.6.Final.jar:/usr/local/hadoop/zookeeper/zookeeper-3.4.13/bin/../lib/log4j-1.2.17.jar:/usr/local/hadoop/zookeeper/zookeeper-3.4.13/bin/../lib/jline-0.9.94.jar:/usr/local/hadoop/zookeeper/zookeeper-3.4.13/bin/../lib/audience-annotations-0.5.0.jar:/usr/local/hadoop/zookeeper/zookeeper-3.4.13/bin/../zookeeper-3.4.13.jar:/usr/local/hadoop/zookeeper/zookeeper-3.4.13/bin/../src/java/lib/*.jar:/usr/local/hadoop/zookeeper/zookeeper-3.4.13/bin/../conf: 2020-04-19 16:05:13,817 [myid:] - INFO [main:Environment@100] - Client environment:java.library.path=/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib 2020-04-19 16:05:13,817 [myid:] - INFO [main:Environment@100] - Client environment:java.io.tmpdir=/tmp 2020-04-19 16:05:13,817 [myid:] - INFO [main:Environment@100] - Client environment:java.compiler=<NA> 2020-04-19 16:05:13,817 [myid:] - INFO [main:Environment@100] - Client environment:os.name=Linux 2020-04-19 16:05:13,817 [myid:] - INFO [main:Environment@100] - Client environment:os.arch=amd64 2020-04-19 16:05:13,817 [myid:] - INFO [main:Environment@100] - Client environment:os.version=3.10.0-862.el7.x86_64 2020-04-19 16:05:13,817 [myid:] - INFO [main:Environment@100] - Client environment:user.name=root 2020-04-19 16:05:13,817 [myid:] - INFO [main:Environment@100] - Client environment:user.home=/root 2020-04-19 16:05:13,817 [myid:] - INFO [main:Environment@100] - Client environment:user.dir=/usr/local/hadoop/zookeeper/zookeeper-3.4.13/bin 2020-04-19 16:05:13,818 [myid:] - INFO [main:ZooKeeper@442] - Initiating client connection, connectString=localhost:2181 sessionTimeout=30000 watcher=org.apache.zookeeper.ZooKeeperMain$MyWatcher@277050dc Welcome to ZooKeeper! 2020-04-19 16:05:13,878 [myid:] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1029] - Opening socket connection to server localhost/0:0:0:0:0:0:0:1:2181. Will not attempt to authenticate using SASL (unknown error) JLine support is enabled 2020-04-19 16:05:14,007 [myid:] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@879] - Socket connection established to localhost/0:0:0:0:0:0:0:1:2181, initiating session 2020-04-19 16:05:14,033 [myid:] - INFO [main-SendThread(localhost:2181):ClientCnxn$SendThread@1303] - Session establishment complete on server localhost/0:0:0:0:0:0:0:1:2181, sessionid = 0x10004d8e0310000, negotiated timeout = 30000WATCHER::WatchedEvent state:SyncConnected type:None path:null [zk: localhost:2181(CONNECTED) 0]

我們看到? controller? ? 是brokerid:0

[zk: localhost:2181(CONNECTED) 2] ls / [cluster, controller_epoch, controller, brokers, zookeeper, admin, isr_change_notification, consumers, log_dir_event_notification, latest_producer_id_block, config] [zk: localhost:2181(CONNECTED) 3] get /controller {"version":1,"brokerid":0,"timestamp":"1586133981273"} cZxid = 0x500000003 ctime = Mon Apr 06 08:46:21 CST 2020 mZxid = 0x500000003 mtime = Mon Apr 06 08:46:21 CST 2020 pZxid = 0x500000003 cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x2000392dd2c0000 dataLength = 54 numChildren = 0 [zk: localhost:2181(CONNECTED) 5]

當(dāng)我們的kafkabrokerid掛了之后，zk會(huì)為我們?cè)趺催x舉，我們將kafka的brokerid:0的節(jié)點(diǎn)? kill掉

查看這個(gè)brokerid為0的節(jié)點(diǎn)進(jìn)程

[root@backup01 bin]# kill -9 19728 [root@backup01 bin]# jps 54464 ZooKeeperMain 12732 Elasticsearch 54750 Jps 14623 QuorumPeerMain [root@backup01 bin]# [zk: localhost:2181(CONNECTED) 7] get /controller {"version":1,"brokerid":1,"timestamp":"1587284613737"} cZxid = 0x600000005 ctime = Sun Apr 19 16:23:33 CST 2020 mZxid = 0x600000005 mtime = Sun Apr 19 16:23:33 CST 2020 pZxid = 0x600000005 cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x3000065a6f40003 dataLength = 54 numChildren = 0 [zk: localhost:2181(CONNECTED) 8]

總結(jié)

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