hachikuji opened a new pull request, #12499: URL: https://github.com/apache/kafka/pull/12499
It is possible currently for a leader to send an `AlterPartition` request to a stale controller which does not have the latest leader epoch discovered through a `LeaderAndIsr` request. In this case, the stale controller returns `FENCED_LEADER_EPOCH`, which causes the partition leader to get stuck. This is a change in behavior following https://github.com/apache/kafka/pull/12032. Prior to that patch, the request would either be accepted (potentially incorrectly) if the `LeaderAndIsr` state matched that on the controller, or it would have returned `NOT_CONTROLLER`. This patch fixes the problem by ensuring that `AlterPartition` is sent to a controller with an epoch which is at least as large as that of the controller which sent the `LeaderAndIsr` request. This ensures that the `FENCED_LEADER_EPOCH` error from the controller can be trusted. A more elegant solution to this problem would probably be to include the controller epoch in the `AlterPartition` request, but this would require a version bump. Alternatively, we considered letting the controller return `UNKNOWN_LEADER_EPOCH` instead of `FENCED_LEADER_EPOCH` when the epoch is larger than what it has in its context. This too likely would require a version bump. Finally, we considered reverting https://github.com/apache/kafka/pull/12032, which would restore the looser validation logic which allows the controller to accept `AlterPartition` requests with larger leader epochs. We rejected this option because we feel it can lead to correctness violations. ### Committer Checklist (excluded from commit message) - [ ] Verify design and implementation - [ ] Verify test coverage and CI build status - [ ] Verify documentation (including upgrade notes) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
