What happens to Java objects when Axis is reloaded by Tomcat?

[Donald Gorgonzola]

From a web service call I access a singleton, so subsequent web service 
calls can access the same object.  Things work fine until Axis is reloaded 
(by Tomcat web app manager).  I can no longer get a handle on the original 
singleton, instead a new singleton is created.

I wouldn't mind this behavior if the original singleton was cleaned up, but 
instead it sticks around.  I know this because I have threads that are still 
able to see the original singleton.  So what I end up with is multiple 
singletons, one for every time Axis is reloaded and no way of getting a 
handle on the old singletons.  The only way I can get rid of them is to 
restart Tomcat.

What happens when Axis is reloaded by Tomcat?
Is there any way to have the singleton objects and threads that were 
associated with Axis before the reload get cleaned up?  Or a way to get a 
handle on these old objects?

I am using Axis 1.1 with Tomcat 5.0.25 and Java 1.4.2.
Here  is some code that calls a web service that accesses a singleton.
/*
* SingletonTest.jws
* Tests accessing a singleton from a web service call.
*/
public class SingletonTest
{
   /** Shows the current value of the singleton and updates with the new 
value. */
   public String
   showAndSet (String newValue)
   {
       String originalValue = Singleton.getInstance().getValue();
       Singleton.getInstance().setValue(newValue);
       return (originalValue);
   }
}

/** Singleton.java */
public class Singleton
{
   private static Singleton singleton = null;
   private String value = "unset";
   /** Singleton so constructor is private. */
   private
   Singleton()
   {
   }
   public static Singleton
   getInstance()
   {
       if (singleton == null) {
           singleton = new Singleton();
       }
       return (singleton);
   }
   public String
   getValue()
   {
       return (value);
   }
   public void
   setValue (String newValue)
   {
       value = newValue;
   }
}

/*
* SingletonTestClient.java
* Test client used to test SingletonTest.jws.
*/
import org.apache.axis.client.Call;
import org.apache.axis.client.Service;
import org.apache.axis.encoding.XMLType;
import javax.xml.rpc.ParameterMode;
public class SingletonTestClient
{
   public static void
   main(String [] args)
       throws Exception
   {
       String endpoint = "http://localhost:8080/axis/SingletonTest.jws";;
       if (args == null || args.length < 1) {
           System.err.println("Usage: SingletonTestClient <name>");
           return;
       }
       String value = args[0];
       String retStr = null;
       Object [] objs = null;
       Service  service = new Service();
       Call     call    = (Call) service.createCall();
       call.addParameter ("showAndSet", XMLType.XSD_STRING, 
ParameterMode.IN );
       objs = new Object [] { value };

       call.setTargetEndpointAddress( new java.net.URL(endpoint) );
       call.setOperationName("showAndSet");
       call.setReturnType(XMLType.XSD_STRING);
       retStr = (String) call.invoke(objs);
       System.out.println("Result: " + retStr);
   }
}
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