public ShutdownExample extends HttpServlet {	
   private int serviceCounter = 0;	
   ...	
   //Access methods for serviceCounter	
   protected synchronized void enteringServiceMethod() {	
      serviceCounter++;	
   }	
   protected synchronized void leavingServiceMethod() {	
      serviceCounter--;	
   }	
   protected synchronized int numServices() {	
      return serviceCounter;	
   }	
}

protected void service(HttpServletRequest req,	
               HttpServletResponse resp)	
               throws ServletException,IOException {	
   enteringServiceMethod();	
   try {	
      super.service(req, resp);	
   } finally {	
      leavingServiceMethod();	
   }	
}

public ShutdownExample extends HttpServlet {	
   private boolean shuttingDown;	
   ...	
   //Access methods for shuttingDown	
   protected setShuttingDown(boolean flag) {	
      shuttingDown = flag;	
   }	
   protected boolean isShuttingDown() {	
      return shuttingDown;	
   }	
}

public void destroy() {	
   /* Check to see whether there are still service methods /*	
   /* running, and if there are, tell them to stop. */	
   if (numServices() > 0) {	
      setShuttingDown(true);	
   }	
	
   /* Wait for the service methods to stop. */	
   while(numServices() > 0) {	
      try {	
         Thread.sleep(interval);	
      } catch (InterruptedException e) {	
      }	
   }	
} 

public void doPost(...) {	
   ...	
   for(i = 0; ((i < lotsOfStuffToDo) &&
      !isShuttingDown()); i++) {	
      try {	
         partOfLongRunningOperation(i);	
      } catch (InterruptedException e) {	
         ...	
      }	
   }	
}