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  1. Kafka
  2. KAFKA-3806

Adjust default values of log.retention.hours and offsets.retention.minutes

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Details

    • Improvement
    • Status: Resolved
    • Minor
    • Resolution: Fixed
    • 0.9.0.1, 0.10.0.0
    • 2.0.0
    • config
    • None

    Description

      Combination of default values of log.retention.hours (168 hours = 7 days) and offsets.retention.minutes (1440 minutes = 1 day) may be dangerous in special cases. Offset retention should be always greater than log retention.

      We have observed the following scenario and issue:

      • Producing of data to a topic was disabled two days ago by producer update, topic wasn't deleted.
      • Consumer consumed all data and properly committed offsets to Kafka.
      • Consumer made no more offset commits for that topic because there was no more incoming data and there was nothing to confirm. (We have auto-commit disabled, I'm not sure how behaves enabled auto-commit.)
      • After one day: Kafka cleared too old offsets according to offsets.retention.minutes.
      • After two days: Long-term running consumer was restarted after update, it didn't find any committed offsets for that topic since they were deleted by offsets.retention.minutes so it started consuming from the beginning.
      • The messages were still in Kafka due to larger log.retention.hours, about 5 days of messages were read again.

      Known workaround to solve this issue:

      • Explicitly configure log.retention.hours and offsets.retention.minutes, don't use defaults.

      Proposals:

      • Prolong default value of offsets.retention.minutes to be at least twice larger than log.retention.hours.
      • Check these values during Kafka startup and log a warning if offsets.retention.minutes is smaller than log.retention.hours.
      • Add a note to migration guide about differences between storing of offsets in ZooKeeper and Kafka (http://kafka.apache.org/documentation.html#upgrade).

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              ewencp Ewen Cheslack-Postava
              turek@avast.com Michal Turek
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                Created:
                Updated:
                Resolved: