MessageDrivenBean: AMQ122000: I''m closing a JMS connection you left open

when sending some messages via a MDB there are some warnings about unclosed JMS connections which then are closed by ActiveMQ. The MDB gets a messageHandler injected which gets a replysender injected whichs method is given below.

This is the warning I do get:

[org.apache.activemq.artemis.jms.client] (Finalizer) AMQ122000: I''m closing a JMS connection you left open. Please make sure you close all JMS connections explicitly before letting them go out of scope! see stacktrace to find out where it was created: java.lang.Exception
at org.apache.activemq.artemis.jms.client.ActiveMQConnection.<init>(ActiveMQConnection.java:155)
at org.apache.activemq.artemis.jms.client.ActiveMQConnectionFactory.createConnectionInternal(ActiveMQConnectionFactory.java:750)
at org.apache.activemq.artemis.jms.client.ActiveMQConnectionFactory.createConnection(ActiveMQConnectionFactory.java:233)
at org.apache.activemq.artemis.jms.client.ActiveMQConnectionFactory.createConnection(ActiveMQConnectionFactory.java:229)
[...]

The warning occurs (not every time) within the following code when the try-block has finished (so directly after log.debug(..)):

    private Message doSendAndReturn(XmlMessageCreator messageCreator) throws JMSException {
    Message message = null;
    try (Session session = cf.createConnection().createSession(false, Session.AUTO_ACKNOWLEDGE);) {
        MessageProducer producer = session.createProducer(jmsReplyQueue);
        message = messageCreator.createMessage(session);

        producer.send(message);
        log.debug("JMSTemplate sended message to myEnvironment with ID "
                + message.getJMSMessageID()
                + "\n Using Thread "
                + Thread.currentThread().getName());
    }
    return message;
}

I still read that these warnings also occur when theres no reference to the connection factory but "cf" is a global singleton variable which is defined via the context:

    @Resource(lookup = "java:/myProject_myEnvironment_factory")
private ConnectionFactory cf;

When setting a break-point on log.debug(...) I can see that it seems to work some times but sometimes not. This method is called about 7 times while the first three times work, then one time throws the warning four times (probably also for every previous call) and so on for a few times. This is reproducable every time I do a specific task within the webapp.

I do not know whats going wrong here.

Any advice would be grateful. Thanks in advance.

I think the problem is that although the session object is defined in the try-with-resource part but there is no explicit variable for the connection within the try-with-resource part.

After changing it from:

 try (Session session = cf.createConnection().createSession(false, Session.AUTO_ACKNOWLEDGE);) {

to:

 try (
            Connection connection = cf.createConnection();
            Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        ) {

I am not getting the warnings any more. Thanks for listening.