Wenbing Shen created KAFKA-10904:
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Summary: There is a misleading log when the replica fetcher thread
handles offsets that are out of range
Key: KAFKA-10904
URL: https://issues.apache.org/jira/browse/KAFKA-10904
Project: Kafka
Issue Type: Improvement
Components: replication
Affects Versions: 2.7.0
Reporter: Wenbing Shen
Attachments: ReplicaFetcherThread-has-a-misleading-log.png
There is ambiguity in the replica fetcher thread's log. When the fetcher thread
is handling with offset out of range, it needs to try to truncate the log. When
the end offset of the follower replica is greater than the log start offset of
the leader replica and smaller than the end offset of the leader replica, the
follower replica will maintain its own fetch offset.However, such cases are
processed together with cases where the follower replica's end offset is
smaller than the leader replica's start offset, resulting in ambiguities in the
log, where the follower replica's fetch offset is reported to reset to the
leader replica's start offset.In fact, it still maintains its own fetch offset,
so this WARN log is misleading to the user.
[2020-11-12 05:30:54,319] WARN (ReplicaFetcherThread-1-1003
kafka.server.ReplicaFetcherThread 70) [ReplicaFetcher replicaId=1
010, leaderId=1003, fetcherId=1] Reset fetch offset for partition
eb_raw_msdns-17 from 1933959108 to current leader's start o
ffset 1883963889
[2020-11-12 05:30:54,320] INFO (ReplicaFetcherThread-1-1003
kafka.server.ReplicaFetcherThread 66) [ReplicaFetcher replicaId=1
010, leaderId=1003, fetcherId=1] Current offset 1933959108 for partition
eb_raw_msdns-17 is out of range, which typically imp
lies a leader change. Reset fetch offset to 1933959108
I think it is more accurate to print the WARN log only when follower replica
really need to truncate the fetch offset to the leader replica's log start
offset.
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