Hadoop HDFS
  1. Hadoop HDFS
  2. HDFS-946

NameNode should not return full path name when lisitng a diretory or getting the status of a file

    Details

    • Type: Improvement Improvement
    • Status: Closed
    • Priority: Major Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 0.21.0
    • Component/s: None
    • Labels:
      None
    • Hadoop Flags:
      Incompatible change, Reviewed

      Description

      FSDirectory#getListring(String src) has the following code:
      int i = 0;
      for (INode cur : contents)

      { listing[i] = createFileStatus(srcs+cur.getLocalName(), cur); i++; }

      So listing a directory will return an array of FileStatus. Each FileStatus element has the full path name. This increases the return message size and adds non-negligible CPU time to the operation.

      FSDirectory#getFileInfo(String) does not need to return the file name either.

      Another optimization is that in the version of FileStatus that's used in the wire protocol, the field path does not need to be Path; It could be a String or a byte array ideally. This could avoid unnecessary creation of the Path objects at NameNode, thus help reduce the GC problem observed when a large number of getFileInfo or getListing operations hit NameNode.

      1. HDFSFileStatus.patch
        57 kB
        Hairong Kuang
      2. HDFSFileStatus1.patch
        58 kB
        Hairong Kuang
      3. HdfsFileStatus3.patch
        59 kB
        Hairong Kuang
      4. HdfsFileStatus4.patch
        59 kB
        Hairong Kuang
      5. HdfsFileStatus-yahoo20.patch
        51 kB
        Hairong Kuang
      6. HdfsFileStatusProxy-Yahoo20.patch
        1 kB
        Hairong Kuang

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            • Assignee:
              Hairong Kuang
              Reporter:
              Hairong Kuang
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              Dates

              • Created:
                Updated:
                Resolved:

                Development