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From "Eddie Epstein (JIRA)" <uima-...@incubator.apache.org>
Subject [jira] Created: (UIMA-1110) The default setting of prefetch=1 is causing problems
Date Sat, 12 Jul 2008 12:47:31 GMT
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

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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