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  1. Hadoop HDFS
  2. HDFS-2071

Use of isConnected() in DataXceiver is invalid

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: 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.

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              • Assignee:
                kihwal Kihwal Lee
                Reporter:
                kihwal Kihwal Lee
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                • Created:
                  Updated:
                  Resolved: