Instance Variables in Stateless Session Bean - state is maintained how?

Question

Server running on GlassFish 3.0

@Stateless(mappedName="messengerservice")
public class MessengerService implements MsnService{

    int count;


    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        count = count+1;
        return count;
    }
}

Client

  for(int i=0;i<5;i++){
      MsnService br = (MsnService) ctx.lookup("java:global/EJbTutorial/MessengerService");
      System.out.println(br.getCount());
  }

Output

1
2
3
4
5

EJB spec says that server maintains a pool of session beans , i increment the value in one instance , re look up hopefully get a new instance and it seems the instance variable value is maintained

How is it possible ? unless server keeps returning me the same instance every time, or is it.

I even tried it executing it in a loop and same result. Can any shed some light

Answer 1

To test , if Stateless Beans indeed pooled , as Tom Anderson suggested , i tried executing it parallel threads

Client

ExecutorService service =  Executors.newFixedThreadPool(10);           

for(int i=0; i<5;i++){
  Future future=  service.submit(new MessengerClient("Thread "+i+" :"));
  }        

service.shutdown();

Output

Thread 0 :1
Thread 1 :1
Thread 3 :1
Thread 4 :1
Thread 2 :1
Thread 1 :2
Thread 2 :3
Thread 3 :4
Thread 4 :5
Thread 0 :6
Thread 1 :7
Thread 2 :8
Thread 3 :9
Thread 4 :10
Thread 0 :11
Thread 1 :2
Thread 2 :12
Thread 3 :13
Thread 4 :14
Thread 2 :15
Thread 1 :16
Thread 3 :17
Thread 4 :18
Thread 0 :19
Thread 0 :20

Well this proves that indeed new instances are used by the threads