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From Jason Dillon <ja...@planet57.com>
Subject Re: Overhead of component creation to send message
Date Thu, 08 Dec 2011 19:01:36 GMT
I did read that javadoc before, just wanted some additional assurance from the community that
this was indeed accurate.  Sounds like it is.  Thanks :-)

--jason



On Dec 8, 2011, at 1:45 AM, Torsten Mielke wrote:

> From the Javadoc of PooledConnectionFactory:
> 
> http://activemq.apache.org/maven/5.5.0/activemq-pool/apidocs/org/apache/activemq/pool/PooledConnectionFactory.html
> 
> 
> 
> "A JMS provider which pools Connection, Session and MessageProducer instances so it can
be used with tools like Camel and Spring's JmsTemplate and MessagListenerContainer. Connections,
sessions and producers are returned to a pool after use so that they can be reused later without
having to undergo the cost of creating them again. NOTE: while this implementation does allow
the creation of a collection of active consumers, it does not 'pool' consumers. Pooling makes
sense for connections, sessions and producers, which are expensive to create and can remain
idle a minimal cost. Consumers, on the other hand, are usually just created at startup and
left active, handling incoming messages as they come. When a consumer is complete, it is best
to close it rather than return it to a pool for later reuse: this is because, even if a consumer
is idle, ActiveMQ will keep delivering messages to the consumer's prefetch buffer, where they'll
get held until the consumer is active again. If you are creating a collection of consumers
(for example, for multi-threaded message consumption), you might want to consider using a
lower prefetch value for each consumer (e.g. 10 or 20), to ensure that all messages don't
end up going to just one of the consumers. See this FAQ entry for more detail: http://activemq.apache.org/i-do-not-receive-messages-in-my-second-consumer.html
"
> 
> Hope this clarifies things.
> 
> Torsten Mielke
> torsten@fusesource.com
> tmielke@blogspot.com
> 
> 
> On Dec 8, 2011, at 6:10 AM, Jason Dillon wrote:
> 
>> Does the activemq-pool stuff cope with pooling connections, sessions and producers?
 Such that a component could access create and use these normally + close them, and under
the covers activemq-pool will do the smart thing and reuse/avoid-close?   Consumers are not
pooled in similar fashion? 
>> 
>> I believe ^^^ is the case, but I just wanted to confirm incase I'm misunderstanding
something.
>> 
>> --jason
>> 
>> 
>> On Nov 18, 2011, at 2:27 AM, Dejan Bosanac wrote:
>> 
>>> Hi Jason,
>>> 
>>> those operations are costly and if your component must open/close it for
>>> every message it will affect performances. In those cases it is recommended
>>> to use pool connection factory which caches those object and improve
>>> performances.
>>> 
>>> See http://activemq.apache.org/jmstemplate-gotchas.html for some more info
>>> on this topic (in case of Spring)
>>> 
>>> Regards
>>> -- 
>>> Dejan Bosanac - http://twitter.com/dejanb
>>> -----------------
>>> The experts in open source integration and messaging - http://fusesource.com
>>> ActiveMQ in Action - http://www.manning.com/snyder/
>>> Blog - http://www.nighttale.net
>>> 
>>> 
>>> On Fri, Nov 18, 2011 at 1:30 AM, Jason Dillon <jason@planet57.com> wrote:
>>> 
>>>> I'm wondering what sort of overhead there is to create and then close) the
>>>> components needed to send a message, specifically after you have a started
>>>> connection and using a vm:// transport.
>>>> 
>>>> I'm working on implementing distributed eventing for a server which
>>>> already has its own eventing built-in (so adapting its events to JMS
>>>> messages published to topics).  The events can come from any thread and be
>>>> sent to different topics based source event details.  That seems to mean
>>>> that for each local event I have to:
>>>> 
>>>> 1) reference destination
>>>> 2) create session
>>>> 3) create producer
>>>> 4) build message for event and send
>>>> 5 ) close producer and session (discard destination)
>>>> 
>>>> #1 looks like its just object creation, but has some parsing of physical
>>>> name (quite a few ops as it looks like)... so could potentially cache these
>>>> (trade a bit of memory for a string lookup over always creating new
>>>> instance)?
>>>> 
>>>> Not sure what overhead there is for #2, #3 or #5.  Is there any
>>>> documentation on roughly what these operations cost?
>>>> 
>>>> The destination + session could change so #3 would have to be done
>>>> anyways, hopefully its cheap?  If #2 is not super cheap, then perhaps its
>>>> better to have the local event handler queue up the publish in a
>>>> BlockingQueue (or similar) so that a single thread + session (or
>>>> potentially small pool of thread+session) could be used to a actually
>>>> perform the publish?
>>>> 
>>>> Does anyone have any insight on to what would be best option for least
>>>> overhead for this use-case?
>>>> 
>>>> --jason
>> 
> 
> 
> 
> 
> 


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