SessionSize.java

import java.io.IOException;
import java.io.Serializable;
import java.lang.reflect.Field;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.commons.lang3.SerializationUtils;
import org.apache.deltaspike.core.util.ExceptionUtils;
import org.omnifaces.filter.HttpFilter;

@WebFilter("/*")
public class ClusterFilter extends HttpFilter {

	@Override
	public void doFilter(HttpServletRequest request, HttpServletResponse response, HttpSession session, FilterChain arg3) throws ServletException,
			IOException {
		if (session != null) {

			Object actualSession = null;
			try {

				Field sessionField = session.getClass().getDeclaredField("session");
				boolean accessable = sessionField.isAccessible();
				sessionField.setAccessible(true);
				actualSession = sessionField.get(session);
				sessionField.setAccessible(accessable);
			} catch (Exception e) {
				ExceptionUtils.throwAsRuntimeException(e);
			}
			byte[] data = SerializationUtils.serialize((Serializable) actualSession);
			System.out.println("Session size " + data.length);
		}
		arg3.doFilter(request, response);

	}

}