how do i invalidate a session in jsf

Question

I have a session scoped bean. WHen logging out i do the following

final HttpSession session = (HttpSession)ctx.getExternalContext().getSession(false);
Map map = ctx.getExternalContext().getSessionMap();
map.clear();
if(session != null) {
    session.invalidate();      
}

and then redirect to login page. but when signing back in i the session bean is populated with data from previous session!