[jira] [Created] (HDFS-8738) Limit Exceptions thrown by DataNode when a client makes socket connection and sends an empty message

[Rajesh Kartha (JIRA)]

Rajesh Kartha created HDFS-8738:
-----------------------------------

             Summary: Limit Exceptions thrown by DataNode when a client makes 
socket connection and sends an empty message
                 Key: HDFS-8738
                 URL: https://issues.apache.org/jira/browse/HDFS-8738
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: datanode
    Affects Versions: 2.7.1
            Reporter: Rajesh Kartha
            Priority: Minor


When a client creates a socket connection to the Datanode and sends an empty 
message, the datanode logs have exceptions like these:

2015-07-08 20:00:55,427 ERROR datanode.DataNode (DataXceiver.java:run(278)) - 
bidev17.rtp.ibm.com:50010:DataXceiver error processing unknown operation  src: 
/127.0.0.1:41508 dst: /127.0.0.1:50010
java.io.EOFException
        at java.io.DataInputStream.readShort(DataInputStream.java:315)
        at 
org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.readOp(Receiver.java:58)
        at 
org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:227)
        at java.lang.Thread.run(Thread.java:745)
2015-07-08 20:00:56,671 ERROR datanode.DataNode (DataXceiver.java:run(278)) - 
bidev17.rtp.ibm.com:50010:DataXceiver error processing unknown operation  src: 
/127.0.0.1:41509 dst: /127.0.0.1:50010
java.io.EOFException
        at java.io.DataInputStream.readShort(DataInputStream.java:315)
        at 
org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.readOp(Receiver.java:58)
        at 
org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:227)
        at java.lang.Thread.run(Thread.java:745)

These can fill up the logs and was recently noticed with an Ambari 2.1 based 
install which tries to check if the datanode is up.

Can be easily reproduced with a simple Java client creating a Socket connection:

        public static void main(String[] args) {
            Socket DNClient;
            try {
                DNClient = new Socket("127.0.0.1", 50010);
                        DataOutputStream os= new 
DataOutputStream(DNClient.getOutputStream());
                        os.writeBytes("");
                        os.close();
                } catch (UnknownHostException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                }

        }





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