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https://issues.apache.org/jira/browse/KAFKA-4900?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15942542#comment-15942542
]
Nick Travers commented on KAFKA-4900:
-------------------------------------
[~onurkaraman] - I like the sound of this theory. While I don't think we hit
_exactly_ the same concurrency bug heading _into_ the controller re-election
loop, I think that what you outline in terms of hitting the metrics issue
sounds reasonable. In our case, we hit a {{ClassCastException}} on controller
(re-)election, which most likely resulted in the metrics (amongst other things)
not being cleaned up.
This also makes sense with what we observed, as each broker hit the same
{{ClassCastException}} (as a result of KAFKA-4914), which left each broker with
controller metrics that were not cleaned up.
It sounds like a potential solution here is to fix both of the underlying
issues that caused the brokers to leave "dirty state" lying around when the
controller election process failed (partially tracked by KAFKA-4447 and
KAFKA-4914), as well as the issue of the controller not cleaning up the state
itself.
> Brokers stuck in controller re-election loop after failing to register metrics
> ------------------------------------------------------------------------------
>
> Key: KAFKA-4900
> URL: https://issues.apache.org/jira/browse/KAFKA-4900
> Project: Kafka
> Issue Type: Bug
> Components: controller, core
> Affects Versions: 0.10.1.1
> Reporter: Nick Travers
>
> We hit this today in one of out three node staging clusters. The exception
> continues to occur on all three nodes.
> {code}
> 2017-03-15 02:17:30,677 ERROR
> [ZkClient-EventThread-35-samsa-zkserver.stage.sjc1.square:26101/samsa]
> server.ZookeeperLeaderElector - Error while electing or becoming leader on
> broker 9
> java.lang.IllegalArgumentException: A metric named 'MetricName
> [name=connection-close-rate,
> group=controller-channel-metrics,description=Connections closed per second in
> the window., tags={broker-id=10}]' already exists, can't register another one.
> at
> org.apache.kafka.common.metrics.Metrics.registerMetric(Metrics.java:380)
> at org.apache.kafka.common.metrics.Sensor.add(Sensor.java:179)
> at org.apache.kafka.common.metrics.Sensor.add(Sensor.java:164)
> at
> org.apache.kafka.common.network.Selector$SelectorMetrics.<init>(Selector.java:617)
> at org.apache.kafka.common.network.Selector.<init>(Selector.java:138)
> at
> kafka.controller.ControllerChannelManager.kafka$controller$ControllerChannelManager$$addNewBroker(ControllerChannelManager.scala:101)
> at
> kafka.controller.ControllerChannelManager$$anonfun$1.apply(ControllerChannelManager.scala:45)
> at
> kafka.controller.ControllerChannelManager$$anonfun$1.apply(ControllerChannelManager.scala:45)
> at scala.collection.immutable.Set$Set3.foreach(Set.scala:163)
> at
> kafka.controller.ControllerChannelManager.<init>(ControllerChannelManager.scala:45)
> at
> kafka.controller.KafkaController.startChannelManager(KafkaController.scala:814)
> at
> kafka.controller.KafkaController.initializeControllerContext(KafkaController.scala:742)
> at
> kafka.controller.KafkaController.onControllerFailover(KafkaController.scala:334)
> at
> kafka.controller.KafkaController$$anonfun$1.apply$mcV$sp(KafkaController.scala:167)
> at
> kafka.server.ZookeeperLeaderElector.elect(ZookeeperLeaderElector.scala:84)
> at
> kafka.server.ZookeeperLeaderElector$LeaderChangeListener$$anonfun$handleDataDeleted$1.apply$mcZ$sp(ZookeeperLeaderElector.scala:146)
> at
> kafka.server.ZookeeperLeaderElector$LeaderChangeListener$$anonfun$handleDataDeleted$1.apply(ZookeeperLeaderElector.scala:141)
> at
> kafka.server.ZookeeperLeaderElector$LeaderChangeListener$$anonfun$handleDataDeleted$1.apply(ZookeeperLeaderElector.scala:141)
> at kafka.utils.CoreUtils$.inLock(CoreUtils.scala:234)
> at
> kafka.server.ZookeeperLeaderElector$LeaderChangeListener.handleDataDeleted(ZookeeperLeaderElector.scala:141)
> at org.I0Itec.zkclient.ZkClient$9.run(ZkClient.java:824)
> at org.I0Itec.zkclient.ZkEventThread.run(ZkEventThread.java:71)
> {code}
> We observe a tight loop of controller (re-)election, i.e. one node hits this
> exception, and leadership transitions to the next, which then hits the
> exception, ad infinitum.
> Producers and consumers appear to be connecting ok, and are able to produce
> and consume messages.
> Relevant data points:
> - prior to this cluster restart, a partition reassignment was attempted for
> a number of topics, which appeared to get stuck in the "in progress" state
> (on the order of days)
> - these topics were subsequently deleted
> - a rolling restart of the cluster was performed was to turn on
> broker-to-broker SSL communication
> - the SSL change has subsequently been _rolled back_ after we observed these
> exceptions
> - the entire cluster was shut down, and nodes brought back one at a time in
> an attempt to clear the exception. We were able to restart the cluster, but
> we continue to see the exceptions
> We also observed, during the same time as the exception above, the following
> exception on all hosts:
> {code}
> 2017-03-15 01:44:04,572 ERROR
> [ZkClient-EventThread-36-samsa-zkserver.stage.sjc1.square:26101/samsa]
> controller.ReplicaStateMachine$BrokerChangeListener - [BrokerChangeListener
> on Controller 10]: Error while handling broker changes
> java.lang.ClassCastException: java.lang.String cannot be cast to
> java.lang.Integer
> at scala.runtime.BoxesRunTime.unboxToInt(BoxesRunTime.java:101)
> at
> kafka.controller.KafkaController$$anonfun$8$$anonfun$apply$2.apply(KafkaController.scala:436)
> at
> scala.collection.LinearSeqOptimized$class.exists(LinearSeqOptimized.scala:93)
> at scala.collection.immutable.List.exists(List.scala:84)
> at
> kafka.controller.KafkaController$$anonfun$8.apply(KafkaController.scala:436)
> at
> kafka.controller.KafkaController$$anonfun$8.apply(KafkaController.scala:435)
> at
> scala.collection.TraversableLike$$anonfun$filterImpl$1.apply(TraversableLike.scala:248)
> 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
> scala.collection.TraversableLike$class.filterImpl(TraversableLike.scala:247)
> at
> scala.collection.TraversableLike$class.filter(TraversableLike.scala:259)
> at scala.collection.AbstractTraversable.filter(Traversable.scala:104)
> at
> kafka.controller.KafkaController.onBrokerStartup(KafkaController.scala:435)
> at
> kafka.controller.ReplicaStateMachine$BrokerChangeListener$$anonfun$handleChildChange$1$$anonfun$apply$mcV$sp$1.apply$mcV$sp(ReplicaStateMachine.scala:374)
> at
> kafka.controller.ReplicaStateMachine$BrokerChangeListener$$anonfun$handleChildChange$1$$anonfun$apply$mcV$sp$1.apply(ReplicaStateMachine.scala:358)
> at
> kafka.controller.ReplicaStateMachine$BrokerChangeListener$$anonfun$handleChildChange$1$$anonfun$apply$mcV$sp$1.apply(ReplicaStateMachine.scala:358)
> at kafka.metrics.KafkaTimer.time(KafkaTimer.scala:33)
> at
> kafka.controller.ReplicaStateMachine$BrokerChangeListener$$anonfun$handleChildChange$1.apply$mcV$sp(ReplicaStateMachine.scala:357)
> at
> kafka.controller.ReplicaStateMachine$BrokerChangeListener$$anonfun$handleChildChange$1.apply(ReplicaStateMachine.scala:356)
> at
> kafka.controller.ReplicaStateMachine$BrokerChangeListener$$anonfun$handleChildChange$1.apply(ReplicaStateMachine.scala:356)
> at kafka.utils.CoreUtils$.inLock(CoreUtils.scala:234)
> at
> kafka.controller.ReplicaStateMachine$BrokerChangeListener.handleChildChange(ReplicaStateMachine.scala:355)
> at org.I0Itec.zkclient.ZkClient$10.run(ZkClient.java:843)
> at org.I0Itec.zkclient.ZkEventThread.run(ZkEventThread.java:71)
> {code}
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