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https://issues.apache.org/jira/browse/KAFKA-9840?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17083444#comment-17083444
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ASF GitHub Bot commented on KAFKA-9840:
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abbccdda commented on pull request #8486: KAFKA-9840: Skip End Offset
validation when the leader epoch is not reliable
URL: https://github.com/apache/kafka/pull/8486
As title suggests.
### Committer Checklist (excluded from commit message)
- [ ] Verify design and implementation
- [ ] Verify test coverage and CI build status
- [ ] Verify documentation (including upgrade notes)
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> Consumer should not use OffsetForLeaderEpoch without current epoch validation
> -----------------------------------------------------------------------------
>
> Key: KAFKA-9840
> URL: https://issues.apache.org/jira/browse/KAFKA-9840
> Project: Kafka
> Issue Type: Bug
> Components: consumer
> Affects Versions: 2.4.1
> Reporter: Jason Gustafson
> Assignee: Boyang Chen
> Priority: Major
>
> We have observed a case where the consumer attempted to detect truncation
> with the OffsetsForLeaderEpoch API against a broker which had become a
> zombie. In this case, the last epoch known to the consumer was higher than
> the last epoch known to the zombie broker, so the broker returned -1 as both
> the end offset and epoch in the response. The consumer did not check for this
> in the response, which resulted in the following message:
> {code}
> Truncation detected for partition topic-1 at offset
> FetchPosition{offset=11859, offsetEpoch=Optional[46],
> currentLeader=LeaderAndEpoch{leader=broker-host (id: 3 rack: null),
> epoch=-1}}, resetting offset to the first offset known to diverge
> FetchPosition{offset=-1, offsetEpoch=Optional[-1],
> currentLeader=LeaderAndEpoch{broker-host (id: 3 rack: null), epoch=-1}}
> (org.apache.kafka.clients.consumer.internals.SubscriptionState:414)
> {code}
> There are a couple ways we the consumer can handle this situation better.
> First, the reason we did not detect the zombie broker is that we did not
> include the current leader epoch in the OffsetForLeaderEpoch request. This
> was likely because of KAFKA-9212. Following this patch, we would not
> initialize the current leader epoch from metadata responses because there are
> cases that we cannot rely on it. But if the client cannot rely on being able
> to detect zombies, then the epoch validation is less useful anyway. So the
> simple solution is to not bother with the validation unless we have a
> reliable current leader epoch.
> Second, the consumer needs to check for the case when the returned offset and
> epoch are not defined. In this case, we have to treat this as a normal
> OffsetOutOfRange case and invoke the reset policy.
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