KAFKA-20434: Consumer group does not recompute assignment when static members rejoin with different assignor#22036
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dajac wants to merge 2 commits intoapache:trunkfrom
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KAFKA-20434: Consumer group does not recompute assignment when static members rejoin with different assignor#22036dajac wants to merge 2 commits intoapache:trunkfrom
dajac wants to merge 2 commits intoapache:trunkfrom
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… members rejoin with a different server-side assignor When all static members of a consumer group using the consumer protocol leave and rejoin with a different server-side assignor, the group does not recompute the target assignment. The `bumpGroupEpoch` flag only considers changes to subscribed topic names and regex but not the preferred server assignor. This patch adds a `hasPreferredServerAssignorChanged` check that compares the effective preferred assignor (falling back to the default when no member has an explicit preference) before and after the member update. The group epoch is bumped when the effective preferred assignor changes, which only happens once a majority of members has switched. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java
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core/src/test/scala/unit/kafka/server/ConsumerGroupHeartbeatRequestTest.scala
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core/src/test/scala/unit/kafka/server/ConsumerGroupHeartbeatRequestTest.scala
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core/src/test/scala/unit/kafka/server/ConsumerGroupHeartbeatRequestTest.scala
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Thanks for the patch! |
- Move preferredServerAssignorChanged below updateRegularExpressionStatus to mirror the bumpGroupEpoch sub-expression order - Use .last instead of .max for epoch comparisons in the integration test - Rewrite test comments to describe intent directly Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Apr 13, 2026
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lgtm, thanks for the patch!
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When all static members of a consumer group using the consumer protocol
leave and rejoin with a different server-side assignor, the group does
not recompute the target assignment. The
bumpGroupEpochflag onlyconsiders changes to subscribed topic names and regex but not the
preferred server assignor.
This patch adds a
hasPreferredServerAssignorChangedcheck thatcompares the effective preferred assignor (falling back to the default
when no member has an explicit preference) before and after the member
update. The group epoch is bumped when the effective preferred assignor
changes, which only happens once a majority of members has switched.