[KAFKA-15510] Follower's lastFetchedEpoch wrongly set when fetch response has no record

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.6.0, 3.5.1
• Fix Version/s: 3.7.0
• Assignee: Chern Yih Cheah
• Reporter: Chern Yih Cheah
• Created: 27/Sep/23 05:21
• Updated: 28/Sep/23 13:17
• Resolved: 28/Sep/23 13:17

Description

A regression is introduced by https://github.com/apache/kafka/pull/13843/files#diff-508e9dc4d52744119dda36d69ce63a1901abfd3080ca72fc4554250b7e9f5242. When the fetch response has no record for a partition, validBytes is 0. In this case, we shouldn't set the last fetch epoch to logAppendInfo.lastLeaderEpoch.asScala since there is no record and it is Optional.empty. We should use currentFetchState.lastFetchedEpoch instead.

An effect of this is truncation of fetch might not work correctly.

 

Issue Links

• links to: GitHub Pull Request #14457