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https://issues.apache.org/jira/browse/DERBY-4807?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12971875#action_12971875
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Myrna van Lunteren commented on DERBY-4807:
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I've been doing some reading and experimenting.

It seems it's known that scheduled tasks run with a priority lower than 
default. 
See for instance these web pages: 
http://serverfault.com/questions/151824/process-runs-slower-as-a-scheduled-task-than-it-does-interactively
http://bdbits.wordpress.com/2010/04/29/setting-a-scheduled-task-process-priority/

I guess having scheduled tasks have lower priority could make sense too, if 
these machines were used for other things than running these scheduled tasks, 
but they're not. 
Still, to my unexperienced eye, there seem to be no other important processes 
running. Perhaps things like firewall checking and clock synchronizations and 
the always present system idle processes and the like end up having a higher 
priority.

So, as suggested on those pages, I changed the priority of my scheduled task by 
exporting it, modifying the priority in the resulting .xml file, and then 
importing the task. I tried priority 4 and got good results, e.g. the 
memory.TriggerTest (scheduled task run with scripts takes about twice as long 
as when started interactively, rather than a factor over 30 slower with default 
priority(7)).
I'll experiment a bit more and report my findings here, then close this.
 

> analyze performance slow-down of suites.All/derbyall combo between Windows XP 
> and Windows 2003 and Windows 2008.
> ----------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-4807
>                 URL: https://issues.apache.org/jira/browse/DERBY-4807
>             Project: Derby
>          Issue Type: Task
>          Components: Test
>    Affects Versions: 10.6.2.1
>         Environment: Windows XP, Windows 2003, Windows 2008, IBM JVM 1.6 
> (SR8), 1.5 (SR11) and weme 6.2
>            Reporter: Myrna van Lunteren
>            Assignee: Myrna van Lunteren
>         Attachments: analysis_suitesall.xls
>
>
> Setting up automated nightly test runs has been troublesome for 10.6 on 
> windows because the set of tests (derbyall/suitesall with 3 different jvms) 
> that completed within a day on a machine with similar hardware but running XP 
> did not complete within a day on a machine running Windows 2008.
> Switching to a machine with windows 2003 appeared to improve matters. 
> Switching to a machine with XP, and the test finished.
> Initially, my focus has been to try to get the tests to run consistently, now 
> I will be analyzing this further.
> I now have a separate machine that has the 3 OSs loaded on it, and will 
> experiment, and gather data, using the 10.6.2 jars so the only difference is 
> the OS.

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