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• This new change is an effort of reducing rebalances during consumer rolling restart. Since we introduced a new version of join group request, this should be a backward compatible change.

Non-goal

We do have some offline discussions on handling leader rejoin case, for example since the broker could also do the subscription monitoring work, we don't actually need to trigger rebalance on leader side blindly based on its rejoin request. However this is a separate topic and we will address it in another KIP. 

Rejected Alternatives

In this pull request, we did an experimental approach to materialize member id on the instance local disk. This approach could reduce the rebalances as expected, but KIP 345 has a few advantages over it:

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