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https://issues.apache.org/jira/browse/KAFKA-6681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16407378#comment-16407378
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Narayan Periwal commented on KAFKA-6681:
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[~yuzhih...@gmail.com]
The partition read by the two consumers did not appear in any of the kafka
broker logs. Partition number 1 of the topic renderCpmAms1 was being consumed
by two consumer instances within a consumer group
The following are the log lines in the server logs related to this topic
{noformat}
[2018-03-14 05:01:53,456] INFO Partition [renderCpmAms1,10] on broker 1:
Shrinking ISR for partition [renderCpmAms1,10] from 1,2,3 to 1,3
(kafka.cluster.Partition)
[2018-03-14 05:02:14,122] INFO Partition [renderCpmAms1,10] on broker 1:
Expanding ISR for partition renderCpmAms1-10 from 1,3 to 1,3,2
(kafka.cluster.Partition)
[2018-03-14 05:01:52,376] INFO Partition [renderCpmAms1,9] on broker 15:
Shrinking ISR for partition [renderCpmAms1,9] from 2,15,1 to 15,1
(kafka.cluster.Partition)
[2018-03-14 05:02:14,193] INFO Partition [renderCpmAms1,9] on broker 15:
Expanding ISR for partition renderCpmAms1-9 from 15,1 to 15,1,2
(kafka.cluster.Partition)
[2018-03-14 05:02:17,510] INFO Partition [renderCpmAms1,11] on broker 2:
Shrinking ISR for partition [renderCpmAms1,11] from 2,4,3 to 2,4
(kafka.cluster.Partition)
[2018-03-14 05:02:17,530] INFO Partition [renderCpmAms1,11] on broker 2: Cached
zkVersion [171] not equal to that in zookeeper, skip updating ISR
(kafka.cluster.Partition)
{noformat}
Wondering, if this error or log line has any corelation with the issue.
{noformat}
[2018-03-14 05:02:17,530] INFO Partition [renderCpmAms1,11] on broker 2: Cached
zkVersion [171] not equal to that in zookeeper, skip updating ISR
(kafka.cluster.Partition)
{noformat}
> Two instances of kafka consumer reading the same partition within a consumer
> group
> ----------------------------------------------------------------------------------
>
> Key: KAFKA-6681
> URL: https://issues.apache.org/jira/browse/KAFKA-6681
> Project: Kafka
> Issue Type: Bug
> Components: consumer
> Affects Versions: 0.10.2.1
> Reporter: Narayan Periwal
> Priority: Critical
> Attachments: server-1.log, server-2.log
>
>
> We have seen this issue with the Kafka consumer, the new library that got
> introduced in 0.9
> With this new client, the group management is done by kafka coordinator,
> which is one of the kafka broker.
> We are using Kafka broker 0.10.2.1 and consumer client version is also
> 0.10.2.1
> The issue that we have faced is that, after rebalancing, some of the
> partitions gets consumed by 2 instances within a consumer group, leading to
> duplication of the entire partition data. Both the instances continue to read
> until the next rebalancing, or the restart of those clients.
> It looks like that a particular consumer goes on fetching the data from a
> partition, but the broker is not able to identify this "stale" consumer
> instance.
> During this time, we also see the underreplicated partition metrics spiking.
> We have hit this twice in production. Please look at it the earliest.
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