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  1. Hadoop HDFS
  2. HDFS-5698

Use protobuf to serialize / deserialize FSImage

    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 2.4.0
    • Component/s: namenode
    • Labels:
      None
    • Target Version/s:
    • Hadoop Flags:
      Reviewed
    • Release Note:
      Use protobuf to serialize/deserialize the FSImage.

      Description

      Currently, the code serializes FSImage using in-house serialization mechanisms. There are a couple disadvantages of the current approach:

      1. Mixing the responsibility of reconstruction and serialization / deserialization. The current code paths of serialization / deserialization have spent a lot of effort on maintaining compatibility. What is worse is that they are mixed with the complex logic of reconstructing the namespace, making the code difficult to follow.
      2. Poor documentation of the current FSImage format. The format of the FSImage is practically defined by the implementation. An bug in implementation means a bug in the specification. Furthermore, it also makes writing third-party tools quite difficult.
      3. Changing schemas is non-trivial. Adding a field in FSImage requires bumping the layout version every time. Bumping out layout version requires (1) the users to explicitly upgrade the clusters, and (2) putting new code to maintain backward compatibility.

      This jira proposes to use protobuf to serialize the FSImage. Protobuf has been used to serialize / deserialize the RPC message in Hadoop.

      Protobuf addresses all the above problems. It clearly separates the responsibility of serialization and reconstructing the namespace. The protobuf files document the current format of the FSImage. The developers now can add optional fields with ease, since the old code can always read the new FSImage.

        Attachments

        1. HDFS-5698-design.pdf
          118 kB
          Haohui Mai
        2. HDFS-5698-branch2.000.patch
          182 kB
          Haohui Mai
        3. HDFS-5698.007.patch
          179 kB
          Haohui Mai
        4. HDFS-5698.006.patch
          179 kB
          Haohui Mai
        5. HDFS-5698.005.patch
          178 kB
          Haohui Mai
        6. HDFS-5698.004.patch
          196 kB
          Haohui Mai
        7. HDFS-5698.003.patch
          178 kB
          Haohui Mai
        8. HDFS-5698.002.patch
          179 kB
          Haohui Mai
        9. HDFS-5698.001.patch
          175 kB
          Haohui Mai
        10. HDFS-5698.000.patch
          107 kB
          Haohui Mai

          Issue Links

          1.
          Save FSImage header in protobuf Sub-task Resolved Haohui Mai
          2.
          Implement compression in the HTTP server of SNN / SBN instead of FSImage Sub-task Resolved Unassigned
          3.
          Remove compression support from FSImage Sub-task Resolved Haohui Mai
          4.
          Serialize INode information in protobuf Sub-task Resolved Haohui Mai
          5.
          Use protobuf to serialize snapshot information Sub-task Resolved Jing Zhao
          6.
          Serialize information for token managers in protobuf Sub-task Resolved Haohui Mai
          7.
          Track progress when loading fsimage Sub-task Resolved Haohui Mai
          8.
          Serialize under-construction file information in FSImage Sub-task Resolved Jing Zhao
          9.
          Serialize CachePool directives in protobuf Sub-task Resolved Haohui Mai
          10.
          Compute the digest before loading FSImage Sub-task Resolved Haohui Mai
          11.
          Serialize symlink in protobuf Sub-task Resolved Haohui Mai
          12.
          Optimize the serialization of PermissionStatus Sub-task Resolved Haohui Mai
          13.
          Implement offline image viewer. Sub-task Resolved Haohui Mai
          14.
          Implement cancellation when saving FSImage Sub-task Resolved Haohui Mai
          15.
          Add a Type field in Snapshot DiffEntry's protobuf definition Sub-task Resolved Jing Zhao
          16.
          Update the stored edit logs to be consistent with the changes in HDFS-5698 branch Sub-task Resolved Haohui Mai
          17.
          Consolidate INodeReference into a separate section Sub-task Closed Jing Zhao
          18.
          Use PBHelper to serialize CacheDirectiveInfoExpirationProto Sub-task Resolved Haohui Mai
          19.
          LoadDelegator should use IOUtils.readFully() to read the magic header Sub-task Resolved Haohui Mai
          20.
          Add annotation for repeated fields in the protobuf definition Sub-task Resolved Haohui Mai
          21.
          Add suffix to generated protobuf class Sub-task Patch Available Tassapol Athiapinya
          22.
          Fixing findbugs and javadoc warnings in the HDFS-5698 branch Sub-task Resolved Haohui Mai
          23.
          The id of a CacheDirective instance does not get serialized in the protobuf-fsimage Sub-task Resolved Haohui Mai

            Activity

              People

              • Assignee:
                wheat9 Haohui Mai
                Reporter:
                wheat9 Haohui Mai
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                Watchers:
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                Dates

                • Created:
                  Updated:
                  Resolved: