Details
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Bug
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Status: Resolved
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Major
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Resolution: Fixed
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3.3.0
Description
In https://issues.apache.org/jira/browse/KAFKA-13419 we found that some consumer didn't reset generation and state after sync group fail with REABALANCE_IN_PROGRESS error.
So we fixed it by reset generationId (no memberId) when sync group fail with REABALANCE_IN_PROGRESS error.
But this change missed the reset part, so another change made in https://issues.apache.org/jira/browse/KAFKA-13891 make this works.
After apply this change, we found that: sometimes consumer will revoker almost 2/3 of the partitions with cooperative enabled. Because if a consumer did a very quick re-join, other consumers will get REABALANCE_IN_PROGRESS in syncGroup and revoked their partition before re-jion. example:
- consumer A1-A10 (ten consumers) joined and synced group successfully with generation 1
- New consumer B1 joined and start a rebalance
- all consumer joined successfully and then A1 need to revoke partition to transfer to B1
- A1 do a very quick syncGroup and re-join, because it revoked partition
- A2-A10 didn't send syncGroup before A1 re-join, so after the send syncGruop, will get REBALANCE_IN_PROGRESS
- A2-A10 will revoke there partitions and re-join
So in this rebalance almost every partition revoked, which highly decrease the benefit of Cooperative rebalance
I think instead of "resetStateAndRejoin when RebalanceInProgressException errors happend in sync group" we need another way to fix it.
Here is my proposal:
- revert the change in https://issues.apache.org/jira/browse/KAFKA-13891
- In Server Coordinator handleSyncGroup when generationId checked and group state is PreparingRebalance. We can send the assignment along with the error code REBALANCE_IN_PROGRESS. ( i think it's safe since we verified the generation first )
- When get the REBALANCE_IN_PROGRESS error in client, try to apply the assignment first and then set the rejoinNeeded = true to make it re-join immediately