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  1. Flink
  2. FLINK-34400

Kafka sources with watermark alignment sporadically stop consuming

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Details

    • Bug
    • Status: Open
    • Major
    • Resolution: Unresolved
    • 1.18.1
    • None
    • None
    • None

    Description

      I have 2 Kafka sources that read from different topics. I have assigned them to the same watermark alignment group, and I have not enabled idleness explicitly in their watermark strategies. One topic remains pretty much empty most of the time, while the other receives a few events per second all the time. Parallelism of the active source is 2, for the other one it's 1, and checkpoints are once every minute.

      This works correctly for some time (10 - 15 minutes in my case) but then 1 of the active sources stops consuming, which causes lag to increase. Weirdly, after another 15 minutes or so, all the backlog is consumed at once, and then everything stops again.

      I'm attaching some logs from the Task Manager where the issue appears. You will notice that the Kafka network client reports disconnections (a long time after the deserializer stopped reporting that events were being consumed), I'm not sure if this is related.

      Attachments

        1. alignment_lags.png
          31 kB
          Alexis Sarda-Espinosa
        2. logs.txt
          11 kB
          Alexis Sarda-Espinosa

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            Unassigned Unassigned
            asardaes Alexis Sarda-Espinosa
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            Dates

              Created:
              Updated: