[KAFKA-6859] Follower should not send OffsetForLeaderEpoch for undefined leader epochs

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.11.0.0
• Fix Version/s: 2.1.0
• Assignee: Stanislav Kozlovski
• Reporter: Anna Povzner
• Created: 04/May/18 01:03
• Updated: 31/Aug/18 00:05
• Resolved: 31/Aug/18 00:05

Description

This is more of an optimization, rather than correctness.

Currently, if the follower on inter broker protocol version 0.11 and higher, but on older message format, it does not track leader epochs. However, will still send OffsetForLeaderEpoch request to the leader with undefined epoch which is guaranteed to return undefined offset, so that the follower truncated to high watermark. Another example is a bootstrapping follower that does not have any leader epochs recorded, 

It is cleaner and more efficient to not send OffsetForLeaderEpoch requests to the follower with undefined leader epochs, since we already know the answer.

Issue Links

• links to: GitHub Pull Request #5320