Page History

...

so that when member name has duplicates, we could refuse commit request from members with an outdated member.id (since we update the mapping upon each join group request). Normally when hitting NO_STATIC_MEMBER_INFO_SET, it could potentially due to the consumer is doing rolling restart, where some members haven't updated their code with new member name. In an edge case where the client hits DUPLICATE_STATIC_MEMBER exception in the response, it is suggesting that some other consumer takes its spot. The client should immediately fail itself to inform end user that there is a configuration bug which is generating duplicate consumers with same identity. For first version of this KIP, we just want to have straightforward handling to expose the error in early stage and reproduce corner cases easily.

When do we rebalance in static membership?

Rebalance happens rarely in static membership (unless scale up/down or leader rejoins). When receiving an existing member's rejoin request, broker will return the cached assignment back to the member, without doing any rebalance.

...