On 29/11/13 12:48, Bruno Matos wrote:
On 11/29/2013 11:17 AM, Toralf Lund wrote:
On 29/11/13 11:19, Gordon Sim wrote:
On 11/29/2013 09:08 AM, Toralf Lund wrote:
Hi,
Just wondering, what gain is there in reusing Sender objects for
the C++
Messaging API? I mean, over doing something like
qpid::messaging::Sender sender=session.createSender(address);
sender.send(message);
sender.close();
every time?
The biggest problem is that the createSender() is synchronous, and
may in some cases involve more than one request to the broker. That
adds to the latency of the response.
[ ... ] I was having the same problem, and someone (sorry for not
remember who) suggested this, that helped:
bool create = false;
Sender sender;
try {
sender = session_.getSender(queue);
} catch (KeyError& e) {
create = true;
}
if (create) {
sender = session_.createSender(queue);
}
The session may already have the sender for the queue, so you just
reuse it.
Well, actually, I've been thinking along those lines, already.
The problem is, that way the senders will never go away, and there will
come a time where they aren't going to be needed as the queues could
come and go even though each one is generally used several times. And
there will be more new senders over time, too, so that everything will
keep building up - which is not very nice.
Now, if I could find a way to tell that a sender is not going to be use
any more because its queue has in fact gone away, I could just clean up
at intervals, but I know of no way of doing that. In fact, there doesn't
even seem to be a direct way to ask what senders actually exist. I could
of course try to keep track of what senders I've created and when they
where used "on the outside", and close the least-recently accessed ones
from time to time - but this might easily get cumbersome, and an
address can in fact still be valid even if it's a long time since it was
used last.
- Toralf
However, if you are able to control the types of reply-addresses you
use (e.g. amq.direct/# where # will be expanded to a uuid),
Yep. I'm still at a stage where I can easily change the addressing
scheme.
So, in this setup, I'd use the "#" bit as subject?
- Toralf
then you could cut down on the distinct number of senders needed,
making caching more likely to help.
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