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https://issues.apache.org/jira/browse/KAFKA-2720?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Guozhang Wang updated KAFKA-2720:
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Description:
Currently the coordinator removes the group (i.e. both removing it from the
cache and writing the tombstone message on its local replica without waiting
for ack) once it becomes an empty group.
This can lead to a few issues such as 1) group removal and creation churns when
a group with very few members are being rebalanced, 2) if the local write is
failed / not propagated to other followers, they can only be removed again when
a new coordinator is migrated and detects the group has no members already.
We could instead piggy-back the periodic offset expiration along with the group
purging as well which removes any groups that had no corresponding offsets in
the cache any more.
was:
Currently the coordinator removes the group (i.e. both removing it from the
cache and writing the tombstone message on its local replica without waiting
for ack) once it becomes an empty group.
This can lead to a few issues such as 1) group removal and creation churns when
a group with very few members are being rebalanced, 2) if the local write is
failed / not propagated to other followers, they can only be removed again when
a new coordinator is migrated and detects the group has no members already.
We could instead piggy-back the periodic offset expiration along with the group
purging as well which removes any groups that had no members already.
> Periodic purging groups in the coordinator
> ------------------------------------------
>
> Key: KAFKA-2720
> URL: https://issues.apache.org/jira/browse/KAFKA-2720
> Project: Kafka
> Issue Type: Sub-task
> Components: consumer
> Reporter: Guozhang Wang
> Assignee: Jason Gustafson
> Fix For: 0.10.1.0
>
>
> Currently the coordinator removes the group (i.e. both removing it from the
> cache and writing the tombstone message on its local replica without waiting
> for ack) once it becomes an empty group.
> This can lead to a few issues such as 1) group removal and creation churns
> when a group with very few members are being rebalanced, 2) if the local
> write is failed / not propagated to other followers, they can only be removed
> again when a new coordinator is migrated and detects the group has no members
> already.
> We could instead piggy-back the periodic offset expiration along with the
> group purging as well which removes any groups that had no corresponding
> offsets in the cache any more.
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