lucasbru commented on PR #22561: URL: https://github.com/apache/kafka/pull/22561#issuecomment-4830205271
@chickenchickenlove Thanks a lot for the hard work! Looking at the docs overall, I think there are a few things worth adding before this lands. The most important one is the stateless topology limitation. `StateDirectory.initializeProcessId()` only persists the processId when `hasPersistentStores=true` — stateless topologies get a new random UUID on every restart. That means the thread-level instance IDs change on each restart, and the broker sees new members every time rather than the same static ones rejoining. Users who add `group.instance.id` to a stateless app will silently get the wrong behavior with no guidance anywhere in the docs. This deserves a note in the 4.4.0 upgrade guide section and in `streams-rebalance-protocol.md`. Second, the existing static membership entry is in the `## Streams API changes in 4.3.0` section, but the implementation merged to trunk (4.4.0). It should move to the 4.4.0 section. Third, the thread-scoped instance ID format isn't documented anywhere. Users need to know that `group.instance.id=my-app` causes threads to register as `my-app-1`, `my-app-2`, etc. — both so they can reason about uniqueness across instances, and so they understand what shows up in admin tools. Fourth, `config-streams.md` has no dedicated entry for `group.instance.id`. Regular consumer static membership has a full entry in `consumer-configs.md` with semantics and caveats. For Streams it's only mentioned in passing in the `group.protocol` description. Since `group.instance.id` is a `ConsumerConfig` rather than a `StreamsConfig` key, this is easy to miss. A short dedicated section in the config doc or a cross-reference from `streams-rebalance-protocol.md` would help. Finally, the existing `CloseOptions` note in the 3.3.0 upgrade guide section still says "only works for static consumer groups at this point" — that caveat should be lifted in the 4.4.0 entry now that streams static membership works. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
