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From "Hiram Chirino (JIRA)" <j...@apache.org>
Subject [jira] Commented: (AMQ-855) Add support for prefetchSize = 0
Date Fri, 01 Sep 2006 18:57:23 GMT
    [ https://issues.apache.org/activemq/browse/AMQ-855?page=comments#action_36892 ] 
            
Hiram Chirino commented on AMQ-855:
-----------------------------------

'm going to start looking into it today.  I may not use the
DataResponse to return the message right away.  I think I would still
prefer to use the normal message dispatching flow and logic.

What I'm thinking is that on timeout, or when receiveNoWait() is
called, and no message has arrived to be dispatched, we dispatch a
message to the consumer letting it know that no message was available.
 Then it can unblock.  The nice thing about this is that you don't get
timing issues between the client and server where the client times out
but the broker actually dispatched the message.


> 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
>         Assigned To: Hiram Chirino
>            Priority: Critical
>             Fix For: 4.1
>
>         Attachments: ActiveMQMessageConsumer.patch, ActiveMQMessageConsumer.patch2, PrefetchSubscription.patch
>
>
> 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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