[jetty-users] Is static ConcurrentHashMap a reliable choice for WebSocketServlet?
Good evening,
In a custom WebSocketServlet in Jetty 9.4.37.v20210219 I would like to
maintain Session objects in a shared data structure.
Is a static data structure like
public final static Map SESSIONS = new
ConcurrentHashMap<>();
a good choice for that?
I have a feeling it does not work reliably. Maybe Jetty starts several
Linux process and thus the static data structure is not shared among them?
Because in my custom WebSocketListener I have a code:
@Override
public void onWebSocketText(String str) {
// here the user is authenticated and mUid is found
Session oldSession = SESSIONS.put(mUid, mSession);
disconnect(oldSession);
}
private void disconnect(Session session) {
LOG.info("disconnect: session={}", session); // surprisingly often
session is null
try {
session.close();
session.disconnect();
} catch (Exception ex) {
// ignore
}
}
And often the old session printed by the above LOG is null, even though I
would expect it be non-null.
Best regards
Alex
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Re: [jetty-users] WebSocketListener.onWebSocketClose called numerous times
On the browser side I had automatic reconnects implemented, whenever the
Websockets connection was closed.
But now I am trying to detect, that a player is already connected in
another browser tab and then send a custom close status 4000 from Jetty (so
that automatic reconnect is disabled there and a dialog is displayed to the
user, offering to reconnect):
// called by the onWebSocketText Jetty-callback
private void handleLogin(String username, String password) throws
Exception {
// check username + password and then send the player her/his open
games
mSession.getRemote().sendStringByFuture(mServlet.getGames(mUid));
// if oldSession is not null and still open,
// then the player has several browser tabs open or
// uses the mobile and the desktop app at the same time
Session oldSession = SESSIONS.put(mUid, mSession);
try {
oldSession.close(4000, "another game session detected");
oldSession.disconnect();
} catch (Exception ex) {
// ignore
}
However this only works sporadically, I rarely see the code 4000 in the
browser.
Is this caused by the half open connections too?
Thank you
Alex
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Re: [jetty-users] WebSocketListener.onWebSocketClose called numerous times
Hi Joakim, I have changed my custom 9.4.37.v20210219 WebSocketServlet to
@Override
public void configure(WebSocketServletFactory factory) {
factory.getPolicy().setIdleTimeout(5 * 60 * 1000);
factory.getPolicy().setMaxBinaryMessageSize(0);
factory.getPolicy().setMaxTextMessageSize(64 * 1024);
factory.register(MyListener.class);
factory.setCreator(new MyCreator(this)));
}
and have started implementing calling sendPing() every 4 minutes for the
connected clients, but then I have read your other message at
https://stackoverflow.com/a/54654700/165071
"Setting Max Idle Timeout and then causing the connection to not be idle by
sending ping/pong isn't ideal."
Do you mean by that, that if my custom WebSocketServlet will send PING
every 4 minutes to the browser clients, then the connection will never be
idle? Or what do you mean by "isn't ideal"? What else could be done here?
Thank you
Alex
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Re: [jetty-users] Session invalidation
Difficult to tell you what is happening with so little information ;) What
version of jetty? What configuration of the session management:
SessionCache, SessionStore, SessionIdManager?
Does your webapp involve forwarding between contexts? Does your webapp have
any filters or 3rd party libraries that might create a session?
Have you used a tool like Chrome's developer panel that shows you the http
dialog going on between the tabs and the server? Or tcpdump/wireshark etc
etc?
Have you turned on DEBUG level logging for org.eclipse.jetty.server.session?
How does SessionState get set onto the Session? Is it via a
HttpSessionListener? If so, Request.getSession() will create a new Session
if one does not exist, and the listener could set the SessionState on it.
Jan
On Fri, 26 Feb 2021 at 13:14, John English wrote:
> I have a webapp requiring a user to log in before doing anything else.
> State information is stored in an object in a session attribute called
> "state". When I log out I do the following:
>
> HttpSession session = request.getSession();
> if (session != null) {
>session.removeAttribute("state");
>try {
> session.invalidate();
>}
>catch (IllegalStateException e) { }
> }
>
> I go to the webapp and log in, then open another tab for the same webapp
> and log out, executing the code above. I then go back to the first tab
> and click a button which sends a POST request to a servlet that starts
> off like this:
>
> HttpSession session = request.getSession();
> SessionState state = (session != null ?
> (SessionState)session.getAttribute("state") : null);
>
> The session and the state are both valid objects after these two lines.
>
> Can anyone tell me what might be happening here?
>
> --
> John English
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--
Jan Bartel
www.webtide.com
*Expert assistance from the creators of Jetty and CometD*
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Re: [jetty-users] WebSocketListener.onWebSocketClose called numerous times
Thank you, Joakim! ___ jetty-users mailing list jetty-users@eclipse.org To unsubscribe from this list, visit https://www.eclipse.org/mailman/listinfo/jetty-users
