Uploaded image for project: 'Hadoop Common'
  1. Hadoop Common
  2. HADOOP-6678

Remove FileContext#isFile, isDirectory and exists

    XMLWordPrintableJSON

Details

    • Improvement
    • Status: Closed
    • Major
    • Resolution: Fixed
    • None
    • 0.21.0
    • fs
    • None
    • Reviewed

    Description

      1. Add a method Iterator<FileStatus> listStatus(Path), which allows HDFS client not to have the whole listing in the memory, benefit more from the iterative listing added in HDFS-985. Move the current FileStatus[] listStatus(Path) to be a utility method.
      2. Remove methods isFile(Path), isDirectory(Path), and exists.
        All these methods are implemented by calling getFileStatus(Path).But most users are not aware of this. They would write code as below:
          FileContext fc = ..;
          if (fc.exists(path)) {
            if (fc.isFile(path)) {
             ...
            } else {
            ...
            }
          }
        

        The above code adds unnecessary getFileInfo RPC to NameNode. In our production clusters, we often see that the number of getFileStatus calls is multiple times of the open calls. If we remove isFile, isDirectory, and exists from FileContext, users have to explicitly call getFileStatus first, it is more likely that they will write more efficient code as follow:

          FileContext fc = ...;
          FileStatus fstatus = fc.getFileStatus(path);
          if (fstatus.isFile() {
            ...
          } else {
            ...
          }
        

      Attachments

        1. hadoop-6678-1.patch
          67 kB
          Eli Collins
        2. hadoop-6678-2.patch
          46 kB
          Eli Collins

        Issue Links

          There are no Sub-Tasks for this issue.

          Activity

            People

              eli Eli Collins
              hairong Hairong Kuang
              Votes:
              0 Vote for this issue
              Watchers:
              5 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved: