Stuck on an issue?

We are seeing similar issues after upgrading from 5.0.2 to 5.0.10. The symptoms are similar: after running a server for several days some ServerSessionImpl are not removed. It doesn’t happen to all sessions though. When we stop new incoming connections to the server the amount of server sessions doesn’t drop to zero even after many hours.

Our current way of coping with this is to set a max queue option so that we can clean at least some sessions.

Configuration:

• Default transports (our clients use mostly websocket)
• timeout = 60000
• maxQueue = 250
• maxInterval = 600000 (10 mins)
• ws.messagesPerFrame = 2
• custom jsonContext which uses addConvertor (that is something I forgot to change)
• Ack extension

Clients run cometd 5.0.10 from npm.

We couldn’t find the root cause and couldn’t replicate the issue ourselves but we have an assumption: clients initiate a connection but then a page reload happens hence leaving session in an unfinished setup. There could be several consequent page reloads.

An example of a session that hit max queue limit despite us setting maxInterval (notice that lastConnected is null)

W|2022-02-15T05:46:17.664Z| =====>>> Session queue maxed for cometdSession 2q4so3ufya9186od1r9q082kgyp7d. 
  Disconnecting cometd session isConnected=false isHandshook=false startedAt=2022-02-15T04:27:33.974207Z lastConnected=null. 

session.setAttribute( "startedAt", OffsetDateTime.now() );
session.addListener( new ServerSession.QueueMaxedListener() {
    @Override
    public boolean queueMaxed( ServerSession session, Queue<ServerMessage> queue, ServerSession sender,
            ServerMessage message ) {
        LOG.warn(
                "=====>>> Session queue maxed for cometdSession {}."
                        + " Disconnecting cometd session isConnected={} isHandshook={} startedAt={} lastConnected={}.",
                cometdSessionId, 
                session.isConnected(), session.isHandshook(),
                session.getAttribute( "startedAt" ), session.getAttribute( "lastConnected" ) );
        session.disconnect();
        return false;
    }
} );

session.addListener( new ServerSession.HeartBeatListener() {
    @Override
    public void onResumed( ServerSession session, ServerMessage message, boolean timeout ) {
        // This is called when server sends /meta/connect to the client
    }

    @Override
    public void onSuspended( ServerSession session, ServerMessage message, long timeout ) {
        // This is called when server receives /meta/connect response from the client
        session.setAttribute( "lastConnected", OffsetDateTime.now() );
    }
} );

We will be interested to test the latest fixes once they are released to maven central.

In order to test the fixes I would also need a new version to be released to Maven Central.