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From "James Strachan" <james.strac...@gmail.com>
Subject Re: receiveNoWait problem
Date Fri, 18 Aug 2006 08:45:42 GMT
On 8/18/06, peter anderson <peter.anderson@egsgroup.com> wrote:
>
>
> James Strachan <james.strachan@...> writes:
>
> >
> > There's not heaps to go on so a few questions. Which version are you
> > using? Do you create the consumers up front and reuse them for each
> > request? Is there a time lag between sending a message and calling
> > receiveNoWait()?
> >
> > Note that in ActiveMQ receiveNoWait() really and truly is that - we
> > don't wait a single millisecond or request-response communication with
> > the broker - if there is a message available it is returned without
> > any delay.
> >
> > Some JMS providers interpret receiveNoWait() as a 'poll the broker and
> > see if there is a message available and if so fetch it'. FWIW now we
> > have support for pull based consumption we could consider adding this
> > feature as an option if people want it - I suspect that might be the
> > behaviour you are expecting.
> >
> > As a workaround try using a timeout of 1000 or something?
> >
>
>
> James,
>
> Thanks for your prompt replay. I am using ActiveMQ 4.0.1 running under
> Tomcat 5.5.17. I am calling the producer servlet first and then the consumer
> servlet.

Does the instantiation of the consumer servlet create the consumer?
Once a consumer is created messages are dispatched asynchronously to
it; so if you create a consumer then immediately call receiveNoWait()
then its typically gonna return null.


> Even if I leave a number of minutes between these events the messages
> are still not being found. However running them in a debugger does work
> which suggest receiveNoWait() is failing.

Maybe its the debugger adds enough time between the createConsumer()
call and the receiveNoWait()


> p.s. are there any admin tools I could use to look at messages
> in the queue ?

Yes...
http://activemq.org/site/how-can-i-monitor-activemq.html
-- 

James
-------
http://radio.weblogs.com/0112098/

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