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https://issues.apache.org/jira/browse/KAFKA-4858?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15905927#comment-15905927
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Vahid Hashemian commented on KAFKA-4858:
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[~jeffwidman] Well, assuming we are using an old client script, we are going to
have the topic created in ZK (because the ZK path creation happens before the
broker is triggered). So the PR improves upon how broker deals with these ZK
topic nodes with very long names. Suggestions are welcome on how to improve the
user experience in such a situation. Thanks.
> Long topic names created using old kafka-topics.sh can prevent newer brokers
> from joining any ISRs
> --------------------------------------------------------------------------------------------------
>
> Key: KAFKA-4858
> URL: https://issues.apache.org/jira/browse/KAFKA-4858
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 0.10.1.1, 0.10.2.0
> Reporter: James Cheng
> Assignee: Vahid Hashemian
>
> I ran into a variant of KAFKA-3219 that resulted in a broker being unable to
> join any ISRs the cluster.
> Prior to 0.10.0.0, the maximum topic length was 255.
> With 0.10.0.0 and beyond, the maximum topic length is 249.
> The check on topic name length is done by kafka-topics.sh prior to topic
> creation. Thus, it is possible to use a 0.9.0.1 kafka-topics.sh script to
> create a 255 character topic on a 0.10.1.1 broker.
> When this happens, you will get the following stack trace (the same one seen
> in KAFKA-3219)
> {code}
> $ TOPIC=$(printf 'd%.0s' {1..255} ) ; bin/kafka-topics.sh --zookeeper
> 127.0.0.1 --create --topic $TOPIC --partitions 1 --replication-factor 2
> Created topic
> "ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd".
> {code}
> {code}
> [2017-03-06 22:01:19,011] ERROR [KafkaApi-2] Error when handling request
> {controller_id=1,controller_epoch=1,partition_states=[{topic=ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd,partition=0,controller_epoch=1,leader=2,leader_epoch=0,isr=[2,1],zk_version=0,replicas=[2,1]}],live_leaders=[{id=2,host=jchengmbpro15,port=9093}]}
> (kafka.server.KafkaApis)
> java.lang.NullPointerException
> at
> scala.collection.mutable.ArrayOps$ofRef$.length$extension(ArrayOps.scala:192)
> at scala.collection.mutable.ArrayOps$ofRef.length(ArrayOps.scala:192)
> at
> scala.collection.IndexedSeqOptimized$class.foreach(IndexedSeqOptimized.scala:32)
> at scala.collection.mutable.ArrayOps$ofRef.foreach(ArrayOps.scala:186)
> at
> scala.collection.TraversableLike$WithFilter.foreach(TraversableLike.scala:732)
> at kafka.log.Log.loadSegments(Log.scala:155)
> at kafka.log.Log.<init>(Log.scala:108)
> at kafka.log.LogManager.createLog(LogManager.scala:362)
> at kafka.cluster.Partition.getOrCreateReplica(Partition.scala:94)
> at
> kafka.cluster.Partition$$anonfun$4$$anonfun$apply$2.apply(Partition.scala:174)
> at
> kafka.cluster.Partition$$anonfun$4$$anonfun$apply$2.apply(Partition.scala:174)
> at scala.collection.mutable.HashSet.foreach(HashSet.scala:78)
> at kafka.cluster.Partition$$anonfun$4.apply(Partition.scala:174)
> at kafka.cluster.Partition$$anonfun$4.apply(Partition.scala:168)
> at kafka.utils.CoreUtils$.inLock(CoreUtils.scala:234)
> at kafka.utils.CoreUtils$.inWriteLock(CoreUtils.scala:242)
> at kafka.cluster.Partition.makeLeader(Partition.scala:168)
> at
> kafka.server.ReplicaManager$$anonfun$makeLeaders$4.apply(ReplicaManager.scala:758)
> at
> kafka.server.ReplicaManager$$anonfun$makeLeaders$4.apply(ReplicaManager.scala:757)
> at
> scala.collection.mutable.HashMap$$anonfun$foreach$1.apply(HashMap.scala:99)
> at
> scala.collection.mutable.HashMap$$anonfun$foreach$1.apply(HashMap.scala:99)
> at
> scala.collection.mutable.HashTable$class.foreachEntry(HashTable.scala:230)
> at scala.collection.mutable.HashMap.foreachEntry(HashMap.scala:40)
> at scala.collection.mutable.HashMap.foreach(HashMap.scala:99)
> at kafka.server.ReplicaManager.makeLeaders(ReplicaManager.scala:757)
> at
> kafka.server.ReplicaManager.becomeLeaderOrFollower(ReplicaManager.scala:703)
> at kafka.server.KafkaApis.handleLeaderAndIsrRequest(KafkaApis.scala:148)
> at kafka.server.KafkaApis.handle(KafkaApis.scala:82)
> at kafka.server.KafkaRequestHandler.run(KafkaRequestHandler.scala:60)
> at java.lang.Thread.run(Thread.java:745)
> {code}
> The topic does not get created on disk, but the broker thinks the topic is
> ready. The broker seems functional, for other topics. I can produce/consume
> to other topics.
> {code}
> $ ./bin/kafka-topics.sh --zookeeper 127.0.0.1 --describe
> Topic:ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd
> PartitionCount:1 ReplicationFactor:2 Configs:
> Topic:
> ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd
> Partition: 0 Leader: 2 Replicas: 2,1 Isr: 2,1
> {code}
> If you stop and restart the broker, it again gets that stack trace. This
> time, the broker fails to join *any* ISRs in the cluster. Notice below that
> broker 2 is out of all ISRs
> {code}
> $ ./bin/kafka-topics.sh --zookeeper 127.0.0.1 --describe
> Topic:ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd
> PartitionCount:1 ReplicationFactor:2 Configs:
> Topic:
> ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd
> Partition: 0 Leader: 1 Replicas: 2,1 Isr: 1
> Topic:small PartitionCount:5 ReplicationFactor:2 Configs:
> Topic: small Partition: 0 Leader: 1 Replicas: 1,2 Isr: 1
> Topic: small Partition: 1 Leader: 1 Replicas: 2,1 Isr: 1
> Topic: small Partition: 2 Leader: 1 Replicas: 1,2 Isr: 1
> Topic: small Partition: 3 Leader: 1 Replicas: 2,1 Isr: 1
> Topic: small Partition: 4 Leader: 1 Replicas: 1,2 Isr: 1
> {code}
> So, it appears that a long topic name that sneaks into the cluster can
> prevent brokers from partipating in the cluster.
> Furthermore, I'm not exactly sure how to delete the offending topic. A
> kafka-topics.sh --delete won't delete the topic because it can't talk to all
> replicas, because the replicas are not in the ISR. We ran into this at work
> today and ended up having to manually delete the topic configuration from
> zookeeper and then did a bounce of all affected brokers. Until we did that,
> those brokers weren't able to join the cluster.
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