[jboss-user] [Clustering/JBoss] - Re: Load-balancing is not happening in cluster

[azheludkov]

Thanks,
Now load balancing works, but some weird issue occurs from time to time.
According to FAQ I created my custom InvokerInterceptor and modified standardjboss.xml to replace JBoss's invoker by my custom one.

When my client makes ejb calls via threads and sometimes I get exceptions like this.

java.lang.NullPointerException
	at org.jboss.invocation.unified.interfaces.UnifiedInvokerHAProxy.invoke(UnifiedInvokerHAProxy.java:255)
	at org.jboss.invocation.InvokerInterceptor.invokeInvoker(InvokerInterceptor.java:365)
	at org.jboss.invocation.InvokerInterceptor.invoke(InvokerInterceptor.java:197)
	at org.jboss.proxy.ejb.RetryInterceptor.invoke(RetryInterceptor.java:176)
	at org.jboss.proxy.TransactionInterceptor.invoke(TransactionInterceptor.java:61)
	at org.jboss.proxy.SecurityInterceptor.invoke(SecurityInterceptor.java:70)
	at org.jboss.proxy.ejb.StatelessSessionInterceptor.invoke(StatelessSessionInterceptor.java:112)
	at org.jboss.proxy.ClientContainer.invoke(ClientContainer.java:100)
	at $Proxy74.submitJob(Unknown Source)
	at com.framework.system.cluster.ClusterJobSubmitter$RunInThread.run(ClusterJobSubmitter.java:118)
	at java.lang.Thread.run(Thread.java:595)  




It looks like ejb instance fail to connect client on return.  Ejb instance did its work on remote sevrver.
Do you have any idea why? 

Here is a code:
1. Custom Invoker (Jar with compiled invoker was placed in jboss-4.2.2.GA\server\all\lib ). 

package com.framework.jboss;
import org.jboss.invocation.*;
public class CustomInvokerInterceptor extends InvokerInterceptor { 
  public boolean hasLocalTarget(Invocation invocation) {
      return false;
  }
}

2. Modified piece of standardjboss.xml 

<invoker-proxy-binding>
      clustered-stateless-unified-invoker
      <invoker-mbean>jboss:service=invoker,type=unifiedha</invoker-mbean>
      <proxy-factory>org.jboss.proxy.ejb.ProxyFactoryHA</proxy-factory>
      <proxy-factory-config>
        <client-interceptors>
          
            org.jboss.proxy.ejb.HomeInterceptor
            org.jboss.proxy.SecurityInterceptor
            org.jboss.proxy.TransactionInterceptor
            org.jboss.proxy.ejb.SingleRetryInterceptor
            <interceptor call-by-value="false">org.jboss.invocation.InvokerInterceptor
            <interceptor call-by-value="true">org.jboss.invocation.MarshallingInvokerInterceptor
          
          
            org.jboss.proxy.ejb.StatelessSessionInterceptor
            org.jboss.proxy.SecurityInterceptor
            org.jboss.proxy.TransactionInterceptor
            org.jboss.proxy.ejb.SingleRetryInterceptor
            <interceptor call-by-value="false">com.framework.jboss.CustomInvokerInterceptor
            <interceptor call-by-value="true">org.jboss.invocation.MarshallingInvokerInterceptor
          
        </client-interceptors>
      </proxy-factory-config>
    </invoker-proxy-binding>

3. Client’s snippet of code:

public class ClusterJobSubmitter {
	
    private JobSubmitterHome m_home = null;  // ejb home
	. . . . . . 
    public void runJob(Ticket jt) throws Exception {
        synchronized (this){ 
	if (m_home==null) {
    	  createEjbHome();
    	}
        }
        RunInThread runner = new RunInThread(jt);
        Thread thread = new Thread(runner);
        thread.start();
     }
    
     class RunInThread implements Runnable {
        Ticket m_jt=null;

         public RunInThread(Ticket jt) {
           m_jt= jt;
        }

        public void run() {
           JobSubmitter execute = null;   \\ ejb remote stab
           try {
        	synchronized (m_home){ 
        	      execute = (JobSubmitter) m_home.create();
        	}
               	execute.submitJob(m_jt);
           } catch (Exception ex) {
	ex.printstacktrace();
           }
        }
     }
}

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