GitHub user apurvam opened a pull request: https://github.com/apache/kafka/pull/4020
KAFKA-6003: Accept appends on replicas and when rebuilding the log unconditionally This is a port of #4004 for the 0.11.0 branch. With this patch so that we _only_ validate appends which originate from the client. In general, once the append is validated and written to the leader the first time, revalidating it is undesirable since we can't do anything if validation fails, and also because it is hard to maintain the correct assumptions during validation, leading to spurious validation failures. For example, when we have compacted topics, it is possible for batches to be compacted on the follower but not on the leader. This case would also lead to an OutOfOrderSequencException during replication. The same applies to when we rebuild state from compacted topics: we would get gaps in the sequence numbers, causing the OutOfOrderSequence. You can merge this pull request into a Git repository by running: $ git pull https://github.com/apurvam/kafka KAKFA-6003-0.11.0-handle-unknown-producer-on-replica Alternatively you can review and apply these changes as the patch at: https://github.com/apache/kafka/pull/4020.patch To close this pull request, make a commit to your master/trunk branch with (at least) the following in the commit message: This closes #4020 ---- commit 0a6a0213c091c8e6b6a9c5ce7655b7e0d06c9db0 Author: Apurva Mehta <apu...@confluent.io> Date: 2017-10-04T20:42:17Z KAFKA-6003: Accept appends on replicas and when rebuilding state from the log unconditionally. With this patch so that we _only_ validate appends which originate from the client. In general, once the append is validated and written to the leader the first time, revalidating it is undesirable since we can't do anything if validation fails, and also because it is hard to maintain the correct assumptions during validation, leading to spurious validation failures. For example, when we have compacted topics, it is possible for batches to be compacted on the follower but not on the leader. This case would also lead to an OutOfOrderSequencException during replication. The same applies to when we rebuild state from compacted topics: we would get gaps in the sequence numbers, causing the OutOfOrderSequence. ---- ---