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https://issues.apache.org/jira/browse/KAFKA-2985?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15115988#comment-15115988
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Jason Gustafson commented on KAFKA-2985:
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[~fridrik] Thanks for the update. The 20 second delay you're seeing is likely
caused by the consumer's session timeout. Basically, when the coordinator tries
to rebalance the group, it needs all members to rejoin the group. If one of the
consumers has died, then the rebalance will take as long as it takes the
coordinator to detect the failure (i.e. the session timeout). You should add a
"consumer.close()" at the end of your test case so that the coordinator knows
that your consumer has left the group. Then there is no need to wait for the
session timeout and the rebalance will complete faster.
> Consumer group stuck in rebalancing state
> -----------------------------------------
>
> Key: KAFKA-2985
> URL: https://issues.apache.org/jira/browse/KAFKA-2985
> Project: Kafka
> Issue Type: Bug
> Components: consumer
> Affects Versions: 0.9.0.0
> Environment: Kafka 0.9.0.0.
> Kafka Java consumer 0.9.0.0
> 2 Java producers.
> 3 Java consumers using the new consumer API.
> 2 kafka brokers.
> Reporter: Jens Rantil
> Assignee: Jason Gustafson
>
> We've doing some load testing on Kafka. _After_ the load test when our
> consumers and have two times now seen Kafka become stuck in consumer group
> rebalancing. This is after all our consumers are done consuming and
> essentially polling periodically without getting any records.
> The brokers list the consumer group (named "default"), but I can't query the
> offsets:
> {noformat}
> jrantil@queue-0:/srv/kafka/kafka$ ./bin/kafka-consumer-groups.sh
> --new-consumer --bootstrap-server localhost:9092 --list
> default
> jrantil@queue-0:/srv/kafka/kafka$ ./bin/kafka-consumer-groups.sh
> --new-consumer --bootstrap-server localhost:9092 --describe --group
> default|sort
> Consumer group `default` does not exist or is rebalancing.
> {noformat}
> Retrying to query the offsets for 15 minutes or so still said it was
> rebalancing. After restarting our first broker, the group immediately started
> rebalancing. That broker was logging this before restart:
> {noformat}
> [2015-12-12 13:09:48,517] INFO [Group Metadata Manager on Broker 0]: Removed
> 0 expired offsets in 0 milliseconds. (kafka.coordinator.GroupMetadataManager)
> [2015-12-12 13:10:16,139] INFO [GroupCoordinator 0]: Stabilized group default
> generation 16 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:10:16,141] INFO [GroupCoordinator 0]: Assignment received from
> leader for group default for generation 16
> (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:10:16,575] INFO [GroupCoordinator 0]: Preparing to restabilize
> group default with old generation 16 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:11:15,141] INFO [GroupCoordinator 0]: Stabilized group default
> generation 17 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:11:15,143] INFO [GroupCoordinator 0]: Assignment received from
> leader for group default for generation 17
> (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:11:15,314] INFO [GroupCoordinator 0]: Preparing to restabilize
> group default with old generation 17 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:12:14,144] INFO [GroupCoordinator 0]: Stabilized group default
> generation 18 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:12:14,145] INFO [GroupCoordinator 0]: Assignment received from
> leader for group default for generation 18
> (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:12:14,340] INFO [GroupCoordinator 0]: Preparing to restabilize
> group default with old generation 18 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:13:13,146] INFO [GroupCoordinator 0]: Stabilized group default
> generation 19 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:13:13,148] INFO [GroupCoordinator 0]: Assignment received from
> leader for group default for generation 19
> (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:13:13,238] INFO [GroupCoordinator 0]: Preparing to restabilize
> group default with old generation 19 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:14:12,148] INFO [GroupCoordinator 0]: Stabilized group default
> generation 20 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:14:12,149] INFO [GroupCoordinator 0]: Assignment received from
> leader for group default for generation 20
> (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:14:12,360] INFO [GroupCoordinator 0]: Preparing to restabilize
> group default with old generation 20 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:15:11,150] INFO [GroupCoordinator 0]: Stabilized group default
> generation 21 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:15:11,152] INFO [GroupCoordinator 0]: Assignment received from
> leader for group default for generation 21
> (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:15:11,217] INFO [GroupCoordinator 0]: Preparing to restabilize
> group default with old generation 21 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:16:10,152] INFO [GroupCoordinator 0]: Stabilized group default
> generation 22 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:16:10,154] INFO [GroupCoordinator 0]: Assignment received from
> leader for group default for generation 22
> (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:16:10,339] INFO [GroupCoordinator 0]: Preparing to restabilize
> group default with old generation 22 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:17:09,155] INFO [GroupCoordinator 0]: Stabilized group default
> generation 23 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:17:09,157] INFO [GroupCoordinator 0]: Assignment received from
> leader for group default for generation 23
> (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:17:09,262] INFO [GroupCoordinator 0]: Preparing to restabilize
> group default with old generation 23 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:18:08,157] INFO [GroupCoordinator 0]: Stabilized group default
> generation 24 (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:18:08,159] INFO [GroupCoordinator 0]: Assignment received from
> leader for group default for generation 24
> (kafka.coordinator.GroupCoordinator)
> [2015-12-12 13:18:08,333] INFO [GroupCoordinator 0]: Preparing to restabilize
> group default with old generation 24 (kafka.coordinator.GroupCoordinator)
> {noformat}
> Our consumers were logging:
> {noformat}
> Dec 12 13:09:17 X.X.X.110 system[27782]: [KafkaTaskExecutorConsumer]
> org.apache.kafka.clients.consumer.internals.AbstractCoordinator Marking the
> coordinator 2147483647 dead.
> Dec 12 13:09:17 X.X.X.110 system[27782]: [KafkaTaskExecutorConsumer]
> org.apache.kafka.clients.consumer.internals.ConsumerCoordinator Error
> UNKNOWN_MEMBER_ID occurred while committing offsets for group default
> Dec 12 13:09:17 X.X.X.110 system[27782]: [KafkaTaskExecutorConsumer]
> org.apache.kafka.clients.consumer.internals.ConsumerCoordinator Auto offset
> commit failed: Commit cannot be completed due to group rebalance
> Dec 12 13:09:17 X.X.X.144 system[9915]: [KafkaTaskExecutorConsumer]
> org.apache.kafka.clients.consumer.internals.AbstractCoordinator Marking the
> coordinator 2147483647 dead.
> Dec 12 13:09:17 X.X.X.144 system[9915]: [KafkaTaskExecutorConsumer]
> org.apache.kafka.clients.consumer.internals.ConsumerCoordinator Error
> UNKNOWN_MEMBER_ID occurred while committing offsets for group default
> Dec 12 13:09:17 X.X.X.144 system[9915]: [KafkaTaskExecutorConsumer]
> org.apache.kafka.clients.consumer.internals.ConsumerCoordinator Auto offset
> commit failed: Commit cannot be completed due to group rebalance
> Dec 12 13:09:17 X.X.X.110 system[27782]: [KafkaTaskExecutorConsumer]
> org.apache.kafka.clients.consumer.internals.ConsumerCoordinator Error
> UNKNOWN_MEMBER_ID occurred while committing offsets for group default
> Dec 12 13:09:17 X.X.X.110 system[27782]: [KafkaTaskExecutorConsumer]
> org.apache.kafka.clients.consumer.internals.ConsumerCoordinator Auto offset
> commit failed:
> Dec 12 13:09:17 X.X.X.110 system[27782]: [KafkaTaskExecutorConsumer]
> org.apache.kafka.clients.consumer.internals.AbstractCoordinator Attempt to
> join group default failed due to unknown member id, resetting and retrying.
> Dec 12 13:09:17 X.X.X.144 system[9915]: [KafkaTaskExecutorConsumer]
> org.apache.kafka.clients.consumer.internals.ConsumerCoordinator Error
> UNKNOWN_MEMBER_ID occurred while committing offsets for group default
> Dec 12 13:09:17 X.X.X.144 system[9915]: [KafkaTaskExecutorConsumer]
> org.apache.kafka.clients.consumer.internals.ConsumerCoordinator Auto offset
> commit failed:
> Dec 12 13:09:17 X.X.X.144 system[9915]: [KafkaTaskExecutorConsumer]
> org.apache.kafka.clients.consumer.internals.AbstractCoordinator Attempt to
> join group default failed due to unknown member id, resetting and retrying.
> {noformat}
> I understand that the broker might start rebalancing if my consumers hasn't
> reported heartbeat in session timeout. This might well have happened during
> my load test. However, the issue here is that the rebalancing doesn't
> stabilize/finish after the load test is done.
> Let me know if I can be of any assistance to track this down.
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