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https://issues.apache.org/jira/browse/KAFKA-3992?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16096662#comment-16096662
]
Guozhang Wang commented on KAFKA-3992:
--------------------------------------
[~cmolter] There are some discussions about whether we should recommend using
same client-ids for different clients in
https://github.com/apache/kafka/pull/3328.
In general `client-ids` are used as distinguishing identifiers for client
metrics (though in customizable reporters, users could choose to ignore the
client-id to aggregate all clients into a single metric; in the default
{{JmxReporter}} impl we choose to have one metric per client) and also for
broker-side request logging, so users are suggested to use different values for
different clients.
As for quotas, like mentioned in the PR we have been suggesting users to apply
the "user id" as the principle if they want to have multiple clients sharing
the same quota.
> InstanceAlreadyExistsException Error for Consumers Starting in Parallel
> -----------------------------------------------------------------------
>
> Key: KAFKA-3992
> URL: https://issues.apache.org/jira/browse/KAFKA-3992
> Project: Kafka
> Issue Type: Bug
> Affects Versions: 0.9.0.0, 0.10.0.0
> Reporter: Alexander Cook
> Assignee: Ewen Cheslack-Postava
> Fix For: 0.11.1.0
>
>
> I see the following error sometimes when I start multiple consumers at about
> the same time in the same process (separate threads). Everything seems to
> work fine afterwards, so should this not actually be an ERROR level message,
> or could there be something going wrong that I don't see?
> Let me know if I can provide any more info!
> Error processing messages: Error registering mbean
> kafka.consumer:type=consumer-node-metrics,client-id=consumer-1,node-id=node--1
> org.apache.kafka.common.KafkaException: Error registering mbean
> kafka.consumer:type=consumer-node-metrics,client-id=consumer-1,node-id=node--1
>
> Caused by: javax.management.InstanceAlreadyExistsException:
> kafka.consumer:type=consumer-node-metrics,client-id=consumer-1,node-id=node--1
> Here is the full stack trace:
> M[?:com.ibm.streamsx.messaging.kafka.KafkaConsumerV9.produceTuples:-1] -
> Error processing messages: Error registering mbean
> kafka.consumer:type=consumer-node-metrics,client-id=consumer-1,node-id=node--1
> org.apache.kafka.common.KafkaException: Error registering mbean
> kafka.consumer:type=consumer-node-metrics,client-id=consumer-1,node-id=node--1
> at
> org.apache.kafka.common.metrics.JmxReporter.reregister(JmxReporter.java:159)
> at
> org.apache.kafka.common.metrics.JmxReporter.metricChange(JmxReporter.java:77)
> at
> org.apache.kafka.common.metrics.Metrics.registerMetric(Metrics.java:288)
> at org.apache.kafka.common.metrics.Sensor.add(Sensor.java:177)
> at org.apache.kafka.common.metrics.Sensor.add(Sensor.java:162)
> at
> org.apache.kafka.common.network.Selector$SelectorMetrics.maybeRegisterConnectionMetrics(Selector.java:641)
> at org.apache.kafka.common.network.Selector.poll(Selector.java:268)
> at org.apache.kafka.clients.NetworkClient.poll(NetworkClient.java:270)
> at
> org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.clientPoll(ConsumerNetworkClient.java:303)
> at
> org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:197)
> at
> org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.poll(ConsumerNetworkClient.java:187)
> at
> org.apache.kafka.clients.consumer.internals.ConsumerNetworkClient.awaitMetadataUpdate(ConsumerNetworkClient.java:126)
> at
> org.apache.kafka.clients.consumer.internals.AbstractCoordinator.ensureCoordinatorKnown(AbstractCoordinator.java:186)
> at
> org.apache.kafka.clients.consumer.KafkaConsumer.pollOnce(KafkaConsumer.java:857)
> at
> org.apache.kafka.clients.consumer.KafkaConsumer.poll(KafkaConsumer.java:829)
> at
> com.ibm.streamsx.messaging.kafka.KafkaConsumerV9.produceTuples(KafkaConsumerV9.java:129)
> at
> com.ibm.streamsx.messaging.kafka.KafkaConsumerV9$1.run(KafkaConsumerV9.java:70)
> at java.lang.Thread.run(Thread.java:785)
> at
> com.ibm.streams.operator.internal.runtime.OperatorThreadFactory$2.run(OperatorThreadFactory.java:137)
> Caused by: javax.management.InstanceAlreadyExistsException:
> kafka.consumer:type=consumer-node-metrics,client-id=consumer-1,node-id=node--1
> at com.sun.jmx.mbeanserver.Repository.addMBean(Repository.java:449)
> at
> com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerWithRepository(DefaultMBeanServerInterceptor.java:1910)
> at
> com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerDynamicMBean(DefaultMBeanServerInterceptor.java:978)
> at
> com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerObject(DefaultMBeanServerInterceptor.java:912)
> at
> com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(DefaultMBeanServerInterceptor.java:336)
> at
> com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(JmxMBeanServer.java:534)
> at
> org.apache.kafka.common.metrics.JmxReporter.reregister(JmxReporter.java:157)
> ... 18 more
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