Hadoop HDFS
  1. Hadoop HDFS
  2. HDFS-2071

Use of isConnected() in DataXceiver is invalid

    Details

    • Type: Bug Bug
    • Status: Resolved
    • Priority: Minor Minor
    • Resolution: Fixed
    • Affects Version/s: 0.23.0
    • Fix Version/s: 0.22.0
    • Component/s: datanode
    • Labels:
      None
    • Hadoop Flags:
      Reviewed

      Description

      The use of Socket.isConnected() in DataXceiver.run() is not valid. It returns false until the connection is made and then always returns true after that. It will never return false after the initial connection is successfully made. Socket.isClosed() or SocketChannel.isOpen() should be used instead, assuming someone is handling SocketException and does Socket.close() or SocketChannel.close(). It seems the op handlers in DataXceiver are diligently using IOUtils.closeStream(), which will invoke SocketChannel.close().

      - } while (s.isConnected() && socketKeepaliveTimeout > 0);
      + } while (!s.isClosed() && socketKeepaliveTimeout > 0);
      

      The effect of this bug is very minor, as the socket is read again right after. If the connection was closed, the readOp() will throw an EOFException, which is caught and dealt with properly. The system still functions normally with probably only few microseconds of extra overhead in the premature connection closure cases.

      1. HDFS-2071.patch
        0.7 kB
        Kihwal Lee

        Issue Links

          Activity

          Kihwal Lee created issue -
          Kihwal Lee made changes -
          Field Original Value New Value
          Link This issue is related to HDFS-941 [ HDFS-941 ]
          Kihwal Lee made changes -
          Assignee Kihwal Lee [ kihwal ]
          Kihwal Lee made changes -
          Attachment HDFS-2071.patch [ 12482696 ]
          Kihwal Lee made changes -
          Status Open [ 1 ] Patch Available [ 10002 ]
          Fix Version/s 0.20.3 [ 12314814 ]
          Todd Lipcon made changes -
          Status Patch Available [ 10002 ] Resolved [ 5 ]
          Hadoop Flags [Reviewed]
          Fix Version/s 0.22.0 [ 12314241 ]
          Fix Version/s 0.20.3 [ 12314814 ]
          Resolution Fixed [ 1 ]

            People

            • Assignee:
              Kihwal Lee
              Reporter:
              Kihwal Lee
            • Votes:
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              Watchers:
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              Dates

              • Created:
                Updated:
                Resolved:

                Development