[jira] [Created] (KAFKA-12936) In-memory stores are always restored from scratch after dropping out of the group

["A. Sophie Blee-Goldman (Jira)" <ji...@apache.org>]

A. Sophie Blee-Goldman created KAFKA-12936:
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             Summary: In-memory stores are always restored from scratch after dropping out of the group
                 Key: KAFKA-12936
                 URL: https://issues.apache.org/jira/browse/KAFKA-12936
             Project: Kafka
          Issue Type: Bug
          Components: streams
            Reporter: A. Sophie Blee-Goldman


Whenever an in-memory store is closed, the actual store contents are garbage collected and the state will need to be restored from scratch if the task is reassigned and re-initialized. We introduced the recycling feature to prevent this from occurring when a task is transitioned from standby to active (or vice versa), but it's still possible for the in-memory state to be unnecessarily wiped out in the case the member has dropped out of the group. In this case, the onPartitionsLost callback is invoked, which will close all active tasks as dirty before the member rejoins the group. This means that all these tasks will need to be restored from scratch if they are reassigned back to this consumer.



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