kgo: work around KIP-345 and KIP-814 limitations if possible #229
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
I noticed fork zywillc#1 attempting to fix a problem that I didn't know existed. After a full day of looking into it, as it turns out, KIP-345's implementation had no solution for restarting leaders while changing interests, and KIP-814 further doesn't close the gap. As a client, we can leverage a little bit of KIP-814 to close the gap ourselves. We only do this for well known balancers because we cannot be sure if custom balancers make weird choices depending on time, number of invocations, instance id / member id oridering, etc., so we cannot rely on balance plans to be the same from one run to the next. We do rely on this for our own balancers. Technically this may not be true if multiple member-id-only members are restarting at once. That's ok. We expect instance id using groups to be filled with instance id members and thus always have the same sort ordering in our balancers. We could add another optional interface to opt in to this enhanced re-check behavior, but I'm not sure how common it is for somebody to: (a) write a custom balancer (b) use instance IDs (c) change topic interests across restarts so we'll just leave the option out for now as it'd be complicated to discover. Regardless, there's a lot of documentation on what's being done and why. Also see KAFKA-13435 and the unaddressed KAFKA-12759
Closed
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
See second commit