[jira] [Created] (KAFKA-14932) Heuristic for increasing the log start offset after replicas are caught up

["José Armando García Sancio (Jira)" <ji...@apache.org>]

José Armando García Sancio created KAFKA-14932:
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             Summary: Heuristic for increasing the log start offset after replicas are caught up
                 Key: KAFKA-14932
                 URL: https://issues.apache.org/jira/browse/KAFKA-14932
             Project: Kafka
          Issue Type: Sub-task
            Reporter: José Armando García Sancio
            Assignee: José Armando García Sancio


The implementation in [https://github.com/apache/kafka/pull/9816] increases the log start offset as soon as a snapshot is created that is greater than the log start offset. This is correct but causes some inefficiency in some cases.
 # Any follower, voters or observers, with an end offset between the leader's log start offset and the leader's latest snapshot will get invalidated. This will cause those follower to fetch the new snapshot and reload it's state machine.
 # Any {{Listener}} or state machine that has a {{nextExpectedOffset()}} less than the latest snapshot will get invalidated. This will cause the state machine to have to reload its state from the latest snapshot.

To minimize the frequency of these reloads KIP-630 proposes adding the following configuration:
 * {{metadata.start.offset.lag.time.max.ms}} - The maximum amount of time that leader will wait for an offset to get replicated to all of the live replicas before advancing the {{{}LogStartOffset{}}}. See section “When to Increase the LogStartOffset”. The default is 7 days.

This description and implementation should be extended to also apply to the state machine, or {{{}Listener{}}}. The local log start offset should be increased when all of the {{{}ListenerContext{}}}'s {{nextExpectedOffset()}} is greater than the offset of the latest snapshot.



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