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https://issues.apache.org/jira/browse/ZOOKEEPER-3814?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17098727#comment-17098727
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Mate Szalay-Beko commented on ZOOKEEPER-3814:
---------------------------------------------
Hello Rajkiran,
did you also change the content of the 'myid' file from 22 to 23 when you
migrated the node?
Please note, that the newer ZooKeeper you use sending it's ID during the leader
election protocol initiation. So if a server still thinks that his ID is 22
then it will send this ID to the others, who will believe the ID and try to
find a host address for this server (either from the config or from the last
committed view).
Kind regards,
Mate
> ZooKeeper caching of config
> ---------------------------
>
> Key: ZOOKEEPER-3814
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3814
> Project: ZooKeeper
> Issue Type: Bug
> Components: leaderElection, quorum, server
> Affects Versions: 3.5.6
> Reporter: Rajkiran Sura
> Priority: Major
>
> Hello,
> We recently upgraded our 5 node ZooKeeper ensemble from v3.4.8 to v3.5.6.
> Encountered no issues as such.
> This is how the ZooKeeper config looks like:
> {quote}tickTime=2000
> dataDir=/zookeeper-data/
> initLimit=5
> syncLimit=2
> maxClientCnxns=2048
> autopurge.snapRetainCount=3
> autopurge.purgeInterval=1
> 4lw.commands.whitelist=stat, ruok, conf, isro, mntr
> authProvider.1=org.apache.zookeeper.server.auth.SASLAuthenticationProvider
> requireClientAuthScheme=sasl
> quorum.cnxn.threads.size=20
> quorum.auth.enableSasl=true
> quorum.auth.kerberos.servicePrincipal= zookeeper/_HOST
> quorum.auth.learnerRequireSasl=true
> quorum.auth.learner.saslLoginContext=QuorumLearner
> quorum.auth.serverRequireSasl=true
> quorum.auth.server.saslLoginContext=QuorumServer
> server.17=node1.foo.bar.com:2888:3888;2181
> server.19=node2.foo.bar.com:2888:3888;2181
> server.20=node3.foo.bar.com:2888:3888;2181
> server.21=node4.foo.bar.com:2888:3888;2181
> server.22=node5.bar.com:2888:3888;2181
> {quote}
> Post upgrade, we had to migrate server.22 on the same node, but with
> *FOO*.bar.com domain name due to kerberos referral issues. And, we used
> different server-identifier, i.e., *23* when we migrated. So, here is how the
> new config looked like:
> {quote}server.17=node1.foo.bar.com:2888:3888;2181
> server.19=node2.foo.bar.com:2888:3888;2181
> server.20=node3.foo.bar.com:2888:3888;2181
> server.21=node4.foo.bar.com:2888:3888;2181
> *server.23=node5.{color:#00875a}foo{color}.bar.com:2888:3888;2181*
> {quote}
> We restarted all the nodes in the ensemble with the above updated config. And
> the migrated node joined the quorum successfully and was serving all clients
> directly connected to it, without any issues.
> Recently, when a leader election happened,
> server.*23*=node5.foo.bar.com(migrated node) was chosen as Leader (as it has
> highest ID). But then, ZooKeeper was unable to serve any clients and *all*
> the servers were _somehow still_ trying to establish a channel to 22 (old DNS
> name: node5.bar.com) and were throwing below error in a loop:
> {quote}{{2020-05-02 01:43:03,026 [myid:23] - WARN
> [WorkerSender[myid=23]:QuorumPeer$QuorumServer@196] - Failed to resolve
> address: node4.bar.com}}
> {{java.net.UnknownHostException: node5.bar.com: Name or service not known}}
> {{ at java.base/java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method)}}
> {{ at
> java.base/java.net.InetAddress$PlatformNameService.lookupAllHostAddr(InetAddress.java:929)}}
> {{ at
> java.base/java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1515)}}
> {{ at
> java.base/java.net.InetAddress$NameServiceAddresses.get(InetAddress.java:848)}}
> {{ at java.base/java.net.InetAddress.getAllByName0(InetAddress.java:1505)}}
> {{ at java.base/java.net.InetAddress.getAllByName(InetAddress.java:1364)}}
> {{ at java.base/java.net.InetAddress.getAllByName(InetAddress.java:1298)}}
> {{ at java.base/java.net.InetAddress.getByName(InetAddress.java:1248)}}
> {{ at
> org.apache.zookeeper.server.quorum.QuorumPeer$QuorumServer.recreateSocketAddresses(QuorumPeer.java:194)}}
> {{ at
> org.apache.zookeeper.server.quorum.QuorumPeer.recreateSocketAddresses(QuorumPeer.java:774)}}
> {{ at
> org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:701)}}
> {{ at
> org.apache.zookeeper.server.quorum.QuorumCnxManager.toSend(QuorumCnxManager.java:620)}}
> {{ at
> org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.process(FastLeaderElection.java:477)}}
> {{ at
> org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.run(FastLeaderElection.java:456)}}
> {{ at java.base/java.lang.Thread.run(Thread.java:834)}}
> {{2020-05-02 01:43:03,026 [myid:23] - WARN
> [WorkerSender[myid=23]:QuorumCnxManager@679] - Cannot open channel to 22 at
> election address node5.bar.com:3888}}
> {{java.net.UnknownHostException: node5.bar.com}}
> {{ at
> java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:220)}}
> {{ at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:403)}}
> {{ at java.base/java.net.Socket.connect(Socket.java:591)}}
> {{ at
> org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:650)}}
> {{ at
> org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:714)}}
> {{ at
> org.apache.zookeeper.server.quorum.QuorumCnxManager.toSend(QuorumCnxManager.java:620)}}
> {{ at
> org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.process(FastLeaderElection.java:477)}}
> {{ at
> org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.run(FastLeaderElection.java:456)}}
> {{ at java.base/java.lang.Thread.run(Thread.java:834)}}
> {quote}
> Fetching config from live ZooKeeper znode also doesn't show "*22*" being a
> member of the ensemble. Its not clear how "22" is still coming into the
> picture.
> {quote}In [4]: zk.get('/zookeeper/config')
> Out[4]:
> ('server.17=node1.foo.bar.com:2888:3888:participant;0.0.0.0:2181\n
> server.19=node2.foo.bar.com:2888:3888:participant;0.0.0.0:2181\n
> server.20=node3.foo.bar.com:2888:3888:participant;0.0.0.0:2181\n
> server.21=node4.foo.bar.com:2888:3888:participant;0.0.0.0:2181\n
> server.23=node5.foo.bar.com:2888:3888:participant;0.0.0.0:2181\n
> version=0',
> ZnodeStat(czxid=0, mzxid=0, ctime=0, mtime=1588399290245, version=-1,
> cversion=0, aversion=-1, ephemeralOwner=0, dataLength=360, numChildren=0,
> pzxid=0))
> {quote}
> We suspected some weird caching issue and restarted ZooKeeper across all the
> nodes but that didn't help. So, whenever node5 becomes the Leader, ID:22 is
> popping up. We even rebooted node5 and that hasn't helped too.
> We also looked at '/zookeeper/config' content from snapshot files and did not
> find any reference to ID:22.
> Any help would be greatly appreciated.
> NOTE: dynamic config is disabled.
> Thanks,
> Rajkiran
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