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Struts & Hibernate
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| | | A matter of memory | A matter of memory 2003-10-27 - By peng wang
Back
Hi All,
I'v adopted the Petstore EJBController pattern for our
application.
I make a little modification that I change
EJBController from
stateful session bean to stateless due to no need for
us to maintain
conversition states. There is a statemachine in the
EJBController,
the statemachine has a hashmap used to cache Actions
which are
event handlers. Because EJBController is now
stateless, it instances
will be pooled and in primary memory. Since each
statemachine caches
a different set of Actions, I'm concerning if the
Actions objects will
cause the memory problem.(We have about 40 Actions.
And the user number
of EJBController online will be very large.)
public class StateMachine implements
java.io.Serializable  {
private EJBControllerLocalEJB ccejb;
private HashMap attributeMap;
private HashMap actionMap;
private SessionContext sc;
public StateMachine(EJBControllerLocalEJB ccejb,
SessionContext sc) {
this.ccejb = ccejb;
this.sc = sc;
attributeMap = new HashMap();
actionMap = new HashMap();
}
public EventResponse processEvent(Event ev) throws
EventException {
String actionName =
ev.getEJBActionClassName();
EventResponse response = null;
if (actionName != null) {
EJBAction action = null;
try {
if (actionMap.get(actionName) !=
null) {
action =
(EJBAction)actionMap.get(actionName);
} else {
action =
(EJBAction)Class.forName(actionName).newInstance();
// ********** caching here
************
actionMap.put(actionName,
action);
}
} catch (Exception ex) {
System.err.println("StateMachine:
error loading " + actionName + " :" + ex);
}
if (action != null) {
action.init(this);
// do the magic
action.doStart();
response = action.perform(ev);
action.doEnd();
}
}
return response;
}
...
}
I have thought of making the Actions class as light as
possible that the Actions call other
stateless EJBs to do services. Does an alternative
strategy needed here, such as implementing
all Actions as Singleton?
Thanks a lot,
wp
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