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From "Jerry Cwiklik (JIRA)" <uima-...@incubator.apache.org>
Subject [jira] Updated: (UIMA-1110) The default setting of prefetch=1 is causing problems
Date Mon, 12 Jan 2009 19:36:02 GMT

     [ https://issues.apache.org/jira/browse/UIMA-1110?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Jerry Cwiklik updated UIMA-1110:

    Attachment: uimaj-as-activemq-UIMA-1110-patch.txt

Created a dedicated ConnectionFactory for temp queues that handle CAS Release Requests. Set
a different prefetch policy for this factory that uses 10 for a prefetch value. 

> The default setting of prefetch=1 is causing problems
> -----------------------------------------------------
>                 Key: UIMA-1110
>                 URL: https://issues.apache.org/jira/browse/UIMA-1110
>             Project: UIMA
>          Issue Type: Bug
>          Components: Async Scaleout
>            Reporter: Eddie Epstein
>            Assignee: Eddie Epstein
>         Attachments: uimaj-as-activemq-UIMA-1110-patch.txt
> The new JMX monitor occasionally shows idle times of many seconds for a scaled out remote
delegate that is getting many CASes per second. Assuming the monitor is correct, the problem
is that AMQ is not evenly distributing the work to all the service instances. Other recent
experiences have demonstrated that uneven distribution is solved with prefetch=0. 
> While there is some possibility that prefetch > 0 may be useful in some situations
for remote delegates, for colocated delegates there is little doubt that a prefetch greater
than 0 cannot help performance and can only screw up load balancing.
> prefetch=0 should be the default everywhere.

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