:- use_module(library(http/http_session)). [det]http_close_session(+SessionID)
[det]http_close_session(+SessionID)http_session(end(SessionId, Peer))
The broadcast is done before the session data is destroyed and the listen-handlers are executed in context of the session that is being closed. Here is an example that destroys a Prolog thread that is associated to a thread:
:- listen(http_session(end(SessionId, _Peer)),
          kill_session_thread(SessionID)).
kill_session_thread(SessionID) :-
        http_session_data(thread(ThreadID)),
        thread_signal(ThreadID, throw(session_closed)).
Succeed without any effect if SessionID does not refer to an active session.
If http_close_session/1 
is called from a handler operating in the current session and the CGI 
stream is still in state
header, this predicate emits a Set-Cookie to 
expire the cookie.
type_error(atom, SessionID)