How to force JSF clean its State Manager?

Question

More specifically, this is AjaxStateManager in Richfaces 3.1.HomeMadePatch/JSF1.1. I am not responsible for these technological choices, and I already read related questions like 1, 2, 3 which basically advice to upgrade versions or switch for a stateless JSF, which I would be very glad to do if I could, but due to the big hugeness of the application I am afraid I can't do this.

Back to the topic, I am currently trying to optimize memory heap consumption. Since my predecessors set a session scope for almost every bean, and set a server timeout of 6 hours (with some javascript refreshing before it expires in the browser), users have very long sessions and keep accumulating memory. I made some optimization on my own (well it is kind of simulating conversation scope: when hitting some pages, I clean everything in the main beans). Now when the users come back to main page their session wheights around 300kb, broken down as follow:

AjaxStateManager$SynchronizedStateHolder: 280kb
Other objects in session: 20kb

Those results were obtained by making heapdump and analyzing memory with Eclipse MAT. As you can see, 93% of the memory is Ajax maintening useless states. I want to force it to release those useless states. Any Idea on how to do this?

I thought about limiting the number of views it can save but in some pages there are some very weird form imbrications that I am unsure it would not break if I did.

Thanks in advance..

score 0 · Accepted Answer · answered May 20 '14 at 13:20

Ok, so just in case, here is a relevant link about the problem, saying basically that there is no fix because it is inherent to the mechanisms of JSF. I resorted to using the parameter step on the number of views, which seems the more clean.

But I also experimented some dirty fixing. I am posting it there for future reference. Use at your own risk, because there is no guarantee.

package com.mycompany.ajaxutils;

import javax.faces.application.StateManager;
import javax.faces.context.FacesContext;
import javax.servlet.http.HttpSession;

import org.ajax4jsf.application.AjaxStateManager;
import org.ajax4jsf.util.LRUMap;

public class AjaxStateHelper {
    private static final AjaxSateManagerUncover asmu = new AjaxSateManagerUncover(null);

    public static void cleanAjaxStateManager() {
        HttpSession currentSession = (HttpSession) FacesContext.getCurrentInstance().getExternalContext()
                .getSession(false);
        LRUMap lrumap = asmu.getLRUMap(currentSession.getAttribute(AjaxStateManager.class.getName()
                + ".VIEW_STATES_MAP"));
        lrumap.clear();
    }

    /**
     * This inner class is needed because we need to make a cast to a SynchronizedStateHolder
     * which is an inner protected class inside AjaxStateManager
     */
    protected static class AjaxSateManagerUncover extends AjaxStateManager {

        public AjaxSateManagerUncover(StateManager parent) {
            super(parent);
        }

        public LRUMap getLRUMap(Object stateMap) {
            SynchronizedStateHolder s = (SynchronizedStateHolder) stateMap;
            return s.getStateMap();
        }
    }
}

Just call AjaxStateHelper.cleanAjaxStateManager(); from wherever you need it in your application and it will free the memory for you. But beware the potential side effects, this is experimental code

How to force JSF clean its State Manager?

1 Answers1