[ https://issues.apache.org/activemq/browse/AMQ-855?page=all ]
james strachan resolved AMQ-855.
--------------------------------
Fix Version/s: 4.1
(was: 4.2)
Resolution: Fixed
I've just committed an implementation to the main trunk if you want to try it
out - or take a look at the test case ZeroPrefetchConsumerTest.
So basically prefetch of zero can be supported for synchronous consumers (where
receive(long) or receive() is called). We throw an exception if you try and use
it for async subscription (consumer.setMessageListener()).
The one issue with the current implementation is that the receive(timeout) must
wait long enough for a message to arrive from the broker; otherwise the method
may return but a message is dispatched just shortly afterwards. So provided you
give a reasonably large receive(timeout) then it should do what you need.
Note that the receiveNoWait() method does not try to pull messages from the
broker since the method is not meant to wait for one to arrive.
> Add support for prefetchSize = 0
> --------------------------------
>
> Key: AMQ-855
> URL: https://issues.apache.org/activemq/browse/AMQ-855
> Project: ActiveMQ
> Issue Type: New Feature
> Components: Broker
> Affects Versions: 4.0, 4.0.1, 4.0.2
> Environment: any
> Reporter: Vadim Pesochinskiy
> Priority: Critical
> Fix For: 4.1
>
>
> This feature would enable to support following test case:
> 2 servers are processing 3 submitted jobs with following processing times 10
> min, 1 min, 1 min. This sequence should finish in 10 minutes as one service
> will pick up the 10 minutes job, meanwhile the other one should manage the
> two 1 minute jobs. Since I cannot set prefetchSize=0, one of the 1 minute
> jobs is sitting in prefetch buffer and the jobs are processed in 11 minutes
> instead of 10.
> This is simplification of the real scenario where I have about 30 consumers
> submitting jobs to 20 consumers through AMQ 4.0.1. I have following problems:
> Messages are sitting in prefetch buffer are not available to processors,
> which results in a lot of idle time.
> Order of processing is random. For some reason Job # 20 is processed after
> Job # 1500. Since senders are synchronously blocked this can result in
> time-outs.
> Some requests are real-time, i.e. there is a user waiting, so the system
> cannot wait, so AMQ-850 does not fix this issue.
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