On 7 Jan 2010, at 22:12, jongraf wrote:
1) So when onMessage() is called, it is actually coming from the
prefetch?
Yes - which by default is 1000
2) I'd like to take the messages from the queue and put them in a
collection
and send that collection to my REST service, this way I only need to
make
one HTTP call. Do you think I'll be able to do this in my
MessageListener?
Should I create a private collection in the Listener?
I'd recommend having a BlockingQueue that you fill fill with messages
from onMessage() - and use another thread (Executor) - to pull
messages from that Queue and batch up for your HTTP call.
Joe Fernandez wrote:
By default, ActiveMQ sends or streams messages to a consumer's local
buffer in batches. The batching of the messages can be controlled
via the
prefetch limit. So AMQ pushes messages to the consumer as opposed to
having the consumer pull each message on demand.
http://activemq.apache.org/what-is-the-prefetch-limit-for.html
So very fast consumers would typically have high prefetch limits
and slow
consumers low limits.
If you set the prefetch limit to 0, the consumer will then have to
pull
each individual message from the broker.
AFAIK, ActiveMQ does not include a timer that, when it expires,
purges a
queue. What about assigning an expiration time to the message?
Joe
http://www.ttmsolutions.com
jongraf wrote:
Hello fellow developers,
I find myself in the midst of the age-old dilemma of needing to
provide
scalable code where our load tests currently indicate that the
code is
otherwise. I am coding a message-driven POJO. Originally I
implemented
the queue using the Spring DefaultMessageListenerContainer and
discovered
that this is invoked upon every message received (hence,
"listener").
Because our load tests are bombarding our server, the performance
benchmarks were not great.
I figured that if I write my own timer instead of a listener,
performance
would improve. I coded a Quartz-triggered method that calls
iterates
over jmsTemplate.recieve() for a given batch size. The messages
are sent
in one batch to a remote REST service.
This has not improved performance. After doing some research, I
found
that a caveat of the jmsTemplate is that you do not really want to
be
calling jmsTemplate.receive() because it opens a new connection &
session
each time. This is bad.
Here is where I need your help:
1) Is there not a way to use the Spring
DefaultMessageListenerContainer
to rid the queue of many messages at once? My confusion lies in the
implementation of the onMessage() method where I believe only one
message
is available at a time.
2) Is there a way I can set a timer so that queue is only purged
when I
want it to be? Perhaps this goes against the MDP pattern but I
would
really love some education here.
The forums seem to point to JMS Transactions as a solution for
batching
objects from a JMS queue. I am also unfamiliar with how to tie
this
into the DefaultMessageListenerContainer.
Any help or direction you could provide would be most appreciated.
Thank you,
Jonathan
Developer from NYC
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