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https://issues.apache.org/jira/browse/KAFKA-14016?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17625551#comment-17625551
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David Jacot edited comment on KAFKA-14016 at 10/28/22 9:30 AM:
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> The sticky assignment algorithm should account for this and IIRC will
> basically consider whoever has the highest valid generation for a partition
> as its previous owner
I think that it does not work like this at the moment but it should.
was (Author: dajac):
> The sticky assignment algorithm should account for this and IIRC will
> basically consider whoever has the highest valid generation for a partition
> as its previous owner
I think that it does not work like this at the moment but it should. One thing
to note it that the generation is reset to -1 when a member gets
REBALANCE_IN_PROGRESS while trying to collect its assignment so it would not
come back with its previous generation in this case.
We have this in the code:
{code:java}
} else if (error == Errors.REBALANCE_IN_PROGRESS) {
log.info("SyncGroup failed: The group began another rebalance. Need to
re-join the group. " +
"Sent generation was {}", sentGeneration);
// consumer didn't get assignment in this generation, so we need to reset
generation
// to avoid joinGroup with out-of-data ownedPartitions in cooperative
rebalance
resetStateOnResponseError(ApiKeys.SYNC_GROUP, error, false);
future.raise(error);
}
{code}
> Revoke more partitions than expected in Cooperative rebalance
> -------------------------------------------------------------
>
> Key: KAFKA-14016
> URL: https://issues.apache.org/jira/browse/KAFKA-14016
> Project: Kafka
> Issue Type: Bug
> Components: clients
> Affects Versions: 3.3.0
> Reporter: Shawn Wang
> Priority: Major
> Labels: new-rebalance-should-fix
>
> 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
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