Tomcat -> Session Timeout

//...
HttpsSession session = request.getSession();
session.invalidate();
session = null;
//...

package com.common.action.analysis;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.suntech.vigiabrt.common.util.MemoryLogger;

public class MemorySessionFilter implements HttpSessionListener, Filter {
    private FilterConfig filterConfig;
    private int level = 15;
    private static final String MEMORY_LEVEL = "freeMemLevel";
    private static List sessions = new ArrayList();

    private static final Log LOG = LogFactory.getLog(MemorySessionFilter.class);

    public void sessionCreated(HttpSessionEvent se) {        
        HttpSession session = se.getSession();
        String idSession = session.getId();        
        LOG.debug("Creating session: " + idSession);
        MemoryLogger.showMemory();
        sessions.add(idSession);
    }

    public void sessionDestroyed(HttpSessionEvent se) {
        HttpSession session = se.getSession();
        String idSession = session.getId();        
        LOG.debug("Destroying session: " + idSession);
        MemoryLogger.showMemory();
        sessions.remove(idSession);
    }

    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
    }

    public void doFilter(ServletRequest req, ServletResponse res,
            FilterChain chain) throws IOException, ServletException {
        
        HttpServletRequest sreq = (HttpServletRequest) req;
        final String servletPath = sreq.getServletPath();
        if (!"/reqLogout.do".equals(servletPath)) { 
            LOG.debug("Active Sessions: " + sessions.size());
            
            double max = (int) MemoryLogger.getMax();
            double total = (int) MemoryLogger.getTotal();
            if (total == max && isCritical(total)) {
                LOG.warn("Memory in a critical level");
                MemoryLogger.showMemory();
                HttpSession session = sreq.getSession();
                String sessionId = session.getId();
                //if (!sessions.contains(sessionId)) {
                    LOG.warn("Kicking user..." + sessionId);
                    System.gc();
                    ((HttpServletResponse) res).sendRedirect("reqLogout.do?cause=errors.low.memory");
                    return;
                //}
            }
        }
        chain.doFilter(sreq, res);
    }
    
    private boolean isCritical(double total) {
        String memoryLevel = filterConfig.getInitParameter(MEMORY_LEVEL);
        try {
            level = Integer.parseInt(memoryLevel);
            if (level < 0 || level > 100) throw new NumberFormatException();
            LOG.warn("Checking memory level: " + level);
        } catch (NumberFormatException e) {
            LOG.warn("\"memoryLevelPerc\" should be an integer value. Using 15%");
        }
        return (((100 * MemoryLogger.getFree()) / total) <= level);
    }

    public void destroy() {
        filterConfig = null;
    }

}