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  1. Hadoop HDFS
  2. HDFS-12645

FSDatasetImpl lock will stall BP service actors and may cause missing blocks

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    Details

    • Type: Bug
    • Status: Open
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: 2.8.0
    • Fix Version/s: None
    • Component/s: datanode
    • Labels:
      None

      Description

      The DN is extremely susceptible to a slow volume due bad locking practices. DN operations require a fs dataset lock. IO in the dataset lock should not be permissible as it leads to severe performance degradation and possibly (temporarily) missing blocks.

      A slow disk will cause pipelines to experience significant latency and timeouts, increasing lock/io contention while cleaning up, leading to more timeouts, etc. Meanwhile, the actor service thread is interleaving multiple lock acquire/releases with xceivers. If many commands are issued, the node may be incorrectly declared as dead.

      HDFS-12639 documents that both actors synchronize on the offer service lock while processing commands. A backlogged active actor will block the standby actor and cause it to go dead too.

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              • Assignee:
                Unassigned
                Reporter:
                daryn Daryn Sharp
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                Dates

                • Created:
                  Updated: