Jason Gustafson created KAFKA-9840:
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Summary: 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
Reporter: Jason Gustafson
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 the 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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