[SNMP4J] Socket closed error in Windows 7

Tue Aug 17 20:07:47 CEST 2010

Hello Frank,
I apologize for that silly mistake and thanks for pointing it out. I've added a 
CountDownLatch so that the main() wouldn't exit unit all requests are being 
responded.
Actually, we had this running in Tomcat..but just want to have a standalone 
program to reproduce the problem quicker. Please let me know if you want me to 
run any further tests on Windows 7.

Code:

package com.some;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;
import java.util.LinkedHashSet;
import java.util.Set;
import java.util.concurrent.CountDownLatch;

import org.apache.log4j.Logger;
import org.snmp4j.CommunityTarget;
import org.snmp4j.PDU;
import org.snmp4j.Snmp;
import org.snmp4j.TimeoutModel;
import org.snmp4j.TransportMapping;
import org.snmp4j.event.ResponseEvent;
import org.snmp4j.event.ResponseListener;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.UdpAddress;
import org.snmp4j.smi.VariableBinding;
import org.snmp4j.transport.DefaultUdpTransportMapping;

public class Snmp4JUtil
{
   private static final Logger LOGGER = Logger.getLogger( Snmp4JUtil.class );   

   private Snmp snmp;
   private final int [] oid = {1, 3, 6, 1, 4, 1 };
   private final ResponseListener listener;

   public Snmp4JUtil( final ResponseListener listener )
   {
      this.listener = listener;

      try
      {         
         final TransportMapping transport = new DefaultUdpTransportMapping();
         this.snmp = new Snmp( transport );
         snmp.setTimeoutModel( getTimeoutModel( new int[]{ 500, 1000 } ) );
         snmp.listen();
      }
      catch (IOException e)
      {
         LOGGER.error( "Snmp4JUtil() Error: " + e.getMessage() );
      }
   }

   public void close()
   {
      try
      {
         snmp.close();
      }
      catch (IOException e)
      {
         LOGGER.error( "close() Error: " + e.getMessage() );
      }
   }

   public void send( final CommunityTarget target )
   {  
      PDU pdu = new PDU();
      pdu.setType( PDU.GETNEXT );                     
      pdu.add( new VariableBinding( new OID( oid ) ) );

      try
      {         
         this.snmp.send( pdu, target, null, listener);
      }
      catch (IOException e)
      {
         LOGGER.error( "send( CommunityTarget ) - address:" + 
target.getAddress() + "; error:" + e.getMessage() );
         e.printStackTrace();
      }
   }

   private TimeoutModel getTimeoutModel( final int[] timeoutsRetries )
   {
      return new TimeoutModel()
      {
         public long getRequestTimeout( final int totalNumberOfRetries,
                                        final long targetTimeout )
         {
            long requestTimeout = 0;

            for ( int i : timeoutsRetries )
            {
               requestTimeout += i;
            }

            return requestTimeout;
         }

         public long getRetryTimeout( final int retryCount,
                                      final int totalNumberOfRetries,
                                      final long targetTimeout )
         {
            return timeoutsRetries[retryCount];
         }
      };
   }  

   public static void main( final String args[] )
      throws Exception
   {  
      final StringBuilder responses = new StringBuilder();

      // A few thousand addresses...just for testing
      final Set<String> addresses = getAddresses( args[0] );

      final CountDownLatch latch = new CountDownLatch( addresses.size() );

      final ResponseListener listener = new ResponseListener()
      {  
         public void onResponse( ResponseEvent event )
         {
            //cancel event
            ((Snmp)event.getSource()).cancel(event.getRequest(), this);

            // output response here.         
            responses.append( "Response: " + event.getResponse() )
               .append( System.getProperty( "line.separator" ) );

            latch.countDown();
            System.out.println("countDown:" + latch.getCount());
         }
      };      

      final Snmp4JUtil snmpUtil = new Snmp4JUtil( listener );

      final Thread t = new Thread(){
        public void run()
        {  
           for ( final String ipAddress : addresses )
           {
              final CommunityTarget target = new CommunityTarget();             

              target.setAddress( new UdpAddress( ipAddress + "/161" ) );
              target.setVersion( SnmpConstants.version1 );
              target.setRetries( 1 );

              snmpUtil.send( target );
           }

           System.out.println("Done requesting..");

           // Wait for few more seconds for responses..just for testing.
           try
           {
              Thread.sleep( 10000 );

              System.out.println( "Writing response to the file.." );           

              writeResponse( responses );
           }
           catch ( Exception e )
           {
              System.err.println( "Error while sleeping/writing: " + 
e.getMessage() );
           }
        }
      };

      t.start();

      System.out.println("Started running the thread and waiting for 
countdown.");

      latch.await();

      System.out.println("Finished waiting..closing snmp.");

      snmpUtil.close();
      System.out.println( "Done." );      
   }

   private static void writeResponse( final StringBuilder sb )
      throws Exception
   {
      final Writer output = new BufferedWriter(new FileWriter( 
"C:/responses.txt" ));

      try 
      {
        output.write( sb.toString() );
      }
      catch ( Exception e )
      {
        System.err.println( "Error while writing responses: " + e.getMessage() 
);
      }
      finally {
        output.close();
      }
   }

   private static Set<String> getAddresses( final String fileName )
      throws Exception
   {
      final Set<String> addresses = new LinkedHashSet<String>(); 
      BufferedReader input = null;
      try
      {
         input = new BufferedReader(new FileReader( fileName ) );

         String strLine;         
         while ((strLine = input.readLine()) != null)   
         {
            if ( strLine.trim().length() > 0 )
            {
               addresses.add( strLine );
            }
         }

      }catch ( Exception e )
      {
        System.err.println( "Error while reading addresses: " + e.getMessage() 
);
      }
      finally
      {
         if ( input != null )
         {
            input.close();
         }
      }

      return addresses;
   }
}

Thanks,
Varma

________________________________
From: Frank Fock <fock at agentpp.com>
To: varma datla <varmakdatla at yahoo.com>
Cc: "snmp4j at agentpp.org" <snmp4j at agentpp.org>
Sent: Tue, August 17, 2010 1:00:01 PM
Subject: Re: [SNMP4J] Socket closed error in Windows 7

Hi,
There is an error in your program: main may return before the thread you started 
is finished. It is not related to SNMP4J other than the new release might be 
executed with a different speed on your system.

Best regards,
Frank

Am 17.08.2010 um 18:30 schrieb varma datla <varmakdatla at yahoo.com>:

> Hello,
> We are using snmp4j-1.9.3d asynchronously to find devices in a network. All is
> working well until we tested it in Windows 7 where it is throwing the  "Socket
> is closed" exception after a few seconds and stops. Even the latest version
> 1.11.1 didn't seemed to work. Luckily we had an older version, snmp4j-1.9.1e,
> which is working just fine without any errors.
> 
> Here are the details. Could you please suggest any ideas on why this is
> happening on Windows 7? or if I'm not using snmp4j appropriately.
> 
> 
> Environment:
> OS- Windows 7 (Firewall is off)
> SNMP4J- 1.9.3d ( also tested with 1.11.1)
> JVM- 1.6.0_13 (also tested with 1.6.0_20)
> Total addresses- 65025.
> Exception:-
> org.snmp4j.MessageException: Socket is closed
> at org.snmp4j.MessageDispatcherImpl.sendPdu(Unknown Source)
> at org.snmp4j.Snmp.sendMessage(Unknown Source)
> at org.snmp4j.Snmp.send(Unknown Source)
> at org.snmp4j.Snmp.send(Unknown Source)
> at com.some.Snmp4JUtil.send(Snmp4JUtil.java:86)
> at com.some.Snmp4JUtil$3.run(Snmp4JUtil.java:155)
> 
> 
> Code:
> package com.some;
> 
> import java.io.BufferedReader;
> import java.io.BufferedWriter;
> import java.io.FileReader;
> import java.io.FileWriter;
> import java.io.IOException;
> import java.io.Writer;
> import java.util.LinkedHashSet;
> import java.util.Set;
> 
> import org.apache.log4j.Logger;
> import org.snmp4j.CommunityTarget;
> import org.snmp4j.PDU;
> import org.snmp4j.Snmp;
> import org.snmp4j.TimeoutModel;
> import org.snmp4j.TransportMapping;
> import org.snmp4j.event.ResponseEvent;
> import org.snmp4j.event.ResponseListener;
> import org.snmp4j.mp.SnmpConstants;
> import org.snmp4j.smi.OID;
> import org.snmp4j.smi.UdpAddress;
> import org.snmp4j.smi.VariableBinding;
> import org.snmp4j.transport.DefaultUdpTransportMapping;
> 
> public class Snmp4JUtil
> {
>   private static final Logger LOGGER = Logger.getLogger( Snmp4JUtil.class );
> 
>   private Snmp snmp;
>   private final int [] oid = {1, 3, 6, 1, 4, 1 };
>   private final ResponseListener listener;
> 
> 
>   public Snmp4JUtil( final ResponseListener listener )
>   {
>      this.listener = listener;
> 
>      try
>      {
>         final TransportMapping transport = new DefaultUdpTransportMapping();
>         this.snmp = new Snmp( transport );
>         snmp.setTimeoutModel( getTimeoutModel( new int[]{ 500, 1000 } ) );
>         snmp.listen();
>      }
>      catch (IOException e)
>      {
>         LOGGER.error( "Snmp4JUtil(). Error: " + e.getMessage() );
>      }
>   }
> 
>   public void close()
>   {
>      try
>      {
>         snmp.close();
>      }
>      catch (IOException e)
>      {
>         LOGGER.error( "close(). Error: " + e.getMessage() );
>      }
>   }
> 
>   public void send( final CommunityTarget target )
>   {
> 
>      final PDU pdu = new PDU();
>      pdu.setType( PDU.GETNEXT );
>      pdu.add( new VariableBinding( new OID( oid ) ) );
> 
>      try
>      {
>         this.snmp.send( pdu, target, null, listener);
>      }
>      catch (IOException e)
>      {
>         LOGGER.error( "send( CommunityTarget ) - address:" +
> target.getAddress() + "; error:" + e.getMessage() );
>         e.printStackTrace();
>      }
>   }
> 
>   private TimeoutModel getTimeoutModel( final int[] timeoutsRetries )
>   {
>      return new TimeoutModel()
>      {
>         public long getRequestTimeout( final int totalNumberOfRetries,
>                                        final long targetTimeout )
>         {
>            long requestTimeout = 0;
> 
>            for ( int i : timeoutsRetries )
>            {
>               requestTimeout += i;
>            }
> 
>            return requestTimeout;
>         }
> 
>         public long getRetryTimeout( final int retryCount,
>                                      final int totalNumberOfRetries,
>                                      final long targetTimeout )
>         {
>            return timeoutsRetries[retryCount];
>         }
>      };
>   }
> 
>   public static void main( final String args[] )
>      throws Exception
>   {
>      final StringBuilder responses = new StringBuilder();
> 
>      final ResponseListener listener = new ResponseListener()
>      {
>         @Override
>         public void onResponse( ResponseEvent event )
>         {
>            //cancel event
>            ((Snmp)event.getSource()).cancel(event.getRequest(), this);
> 
>            // output response here.
>            responses.append( "Response: " + event.getResponse() )
>               .append( System.getProperty( "line.separator" ) );
>         }
>      };
> 
>      final Snmp4JUtil snmpUtil = new Snmp4JUtil( listener );
> 
>      // A few thousand addresses...just for testing
>      final Set<String> addresses = getAddresses( args[0] );
> 
>      final Thread t = new Thread(){
>        public void run()
>        {
>           for ( final String ipAddress : addresses )
>           {
>              final CommunityTarget target = new CommunityTarget();
> 
>              target.setAddress( new UdpAddress( ipAddress + "/161" ) );
>              target.setVersion( SnmpConstants.version1 );
>              target.setRetries( 1 );
> 
>              snmpUtil.send( target );
>           }
> 
>           System.out.println("Done requesting..");
> 
>           // Wait for few more seconds for responses..just for testing.
>           try
>           {
>              Thread.sleep( 10000 );
> 
>              System.out.println( "Writing response to the file.." );
>              writeResponse( responses );
> 
>              snmpUtil.close();
>              System.out.println( "Done." );
>           }
>           catch ( Exception e )
>           {
>              System.err.println( "Error while sleeping/writing: " +
> e.getMessage() );
>           }
>        }
>      };
> 
>      t.start();
>   }
> 
>   private static void writeResponse( final StringBuilder sb )
>      throws Exception
>   {
>      final Writer output = new BufferedWriter(new FileWriter(
> "C:/responses.txt" ));
> 
>      try
>      {
>        output.write( sb.toString() );
>      }
>      catch ( Exception e )
>      {
>        System.err.println( "Error while writing responses: " + e.getMessage()
> );
>      }
>      finally {
>        output.close();
>      }
>   }
> 
>   private static Set<String> getAddresses( final String fileName )
>      throws Exception
>   {
>      final Set<String> addresses = new LinkedHashSet<String>();
>      BufferedReader input = null;
>      try
>      {
>         input = new BufferedReader(new FileReader( fileName ) );
> 
>         String strLine;
>         while ((strLine = input.readLine()) != null)
>         {
>            if ( strLine.trim().length() > 0 )
>            {
>               addresses.add( strLine );
>            }
>         }
> 
>      }catch ( Exception e )
>      {
>        System.err.println( "Error while reading addresses: " + e.getMessage()
> );
>      }
>      finally
>      {
>         if ( input != null )
>         {
>            input.close();
>         }
>      }
> 
>      return addresses;
>   }
> }
> 
> 
> Thank you and I appreciate your help.
> 
> Varma
> 
> 
> 
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