If you only want to get a single message it might make more sense to use
[possibly non-prefetching if really only wanting 1 message]
consumer.receive(..) style calls rather than a MessageListener.
Opening and closing a consumer and session per-message is quite
inefficient. Are you also closing the connection after each message, or
does the application reuse it to create a new session and consumer+listener
for future work? If the latter it definitely makes sense to just leave the
consumer open and reuse it to get each message in turn. Depending on the
number of consumers and whether they are competing, it may even make sense
to actually use prefetching at that point too.
The reason the session.close() throws is that the original JMS 1.1 spec
described it such that the client should effectively deadlock itself in
that situation. JMS 2 changed the spec description to say it could throw,
as many impls did, or could close, but since it isn't portable as there is
different behaviour, doing so should be avoided.
That said, calling consumer.close() should work, its possible there is a
bug there, depending on what you are doing overall.
You dont say what ack mode you are using. The message.acknowledge() method
is to be ignored for anything but use of the CLIENT_ACK session mode (or
the client has an individual-ack extension/non-JMS ack mode too), at which
point note that it acks all prior messages received on the session, not
just the message it is called on (unless using the extension individual ack
mode is being used, when will only do the message its called on). Though
those would be effectively the same if you only get 1 message at a time.
On Thu, 29 Sept 2022 at 23:01, John Lilley
<john.lil...@redpointglobal.com.invalid> wrote:
> We have an application that should read a single message from a queue (a
> “job” queue) and then stop processing more messages. Think of it as a
> “batch request”. This is entirely using the JMS driver. Is there a good
> pattern for this?
>
>
>
> Under ActiveMQ 5, I call consumer.close(), session.close() from
> onMessage() and that works fine. However, session.close() is not allowed
> under Artemis (and maybe it was always wrong).
>
>
>
> I’ve tried calling only consumer.close(), and leave the session open. But
> the message is not ACked. Explicitly calling message.acknowledge() doesn’t
> work either, because it gets to >>> and individualAck is false:
>
>
>
> *public void *acknowledge() *throws *JMSException {
> *if *(*session *!= *null*) {
> *try *{
> *if *(*session*.isClosed()) {
> *throw *ActiveMQClientMessageBundle.*BUNDLE*.sessionClosed();
> }
> >>> *if *(*individualAck*) {
> *message*.individualAcknowledge();
> }
>
>
>
> Going back to the original question, what is the recommended pattern for
> this?
>
>
>
> Thanks
>
> john
>
> [image: rg] <https://www.redpointglobal.com/>
>
> John Lilley
>
> Chief Architect, Redpoint Global Inc.
>
> 888 Worcester Street, Suite 200 Wellesley, MA 02482
>
> *M: *+1 7209385761 <+1%207209385761> | john.lil...@redpointglobal.com
>
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