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  1. Hadoop HDFS
  2. HDFS-7990

IBR delete ack should not be delayed

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 2.0.0-alpha
    • Fix Version/s: 2.8.0, 2.7.4, 3.0.0-alpha1
    • Component/s: namenode
    • Labels:
      None
    • Target Version/s:
    • Hadoop Flags:
      Reviewed

      Description

      HDFS-395 added the incremental BR feature. A concern was avoiding a race condition with ack-ing block invalidates followed by the directory scanner re-adding the block before the async delete service removes the block, possibly resulting in a full BR that includes the previously delete ack-ed block.

      The solution was to batch & delay block deletion acks via a hardcoded interval of 100 * heartbeat interval (default: 5min). The delay isn't required:

      1. The FSDatasetSpi tracks blocks pending deletions precisely so the scanner won't re-add the block to the volume map
      2. Block receiving, received, and deleted go into the same pending report. A block received event will trigger an immediate IBR which includes the deletion acks. Ie. The delay is meaningless for all but a quiescent cluster
      3. Failing to promptly report deleted blocks on a quiescent cluster prevents the NN from updating the block maps to remove the locations

        Attachments

        1. HDFS-7990.patch
          7 kB
          Daryn Sharp
        2. HDFS-7990-branch-2.7.01.patch
          7 kB
          Konstantin Shvachko

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              • Assignee:
                daryn Daryn Sharp
                Reporter:
                daryn Daryn Sharp
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                Dates

                • Created:
                  Updated:
                  Resolved: