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From "Bernhard Huber" <bh22...@i-one.at>
Subject Re: AW: LogKit - FileRotation
Date Tue, 14 Aug 2001 22:08:37 GMT
Hi,
I think there is cultural misunderstanding.
In germany, and austria too, dots in numbers are
written as comma.
Thus it took not 1503 seconds but 1 second and 503 milli seconds.
So I think the absolute values are quite okay for writting
2270065 bytes in 1 seconds and 863 milli secnds.

My indention mailing the time results, was the question about
variation.

Thanks, for your eloborated answer.
bye



----- Originalnachricht -----
Von: Berin Loritsch <bloritsch@apache.org>
Datum: Dienstag, August 14, 2001 10:15 pm
Betreff: Re: AW: LogKit - FileRotation

> Bernhard Huber wrote:
> > 
> > Hi
> > variance of between what?
> > Between 1,503 and 1,502 I don't know.
> > 
> > 1)Testcase: testSizeRotationUniqueFilename took 1,503 sec
> > 1)Testcase: testSizeRotationRevolingFilename took 1,502 sec
> > 2)Testcase: testTimeRotationUniqueFilename took 10,004 sec
> > 2)Testcase: testTimeRotationRevolvingFilename took 10,005 sec
> 
> Before we worry about 1 or 2 second variations, I want to take the
> time to comment about performance benchmarking.  A benchmark is only
> useful when it documents consistent trends in your algorithm.  It is
> not good for absolute numbers, as they have to be normalized in some
> way (usually to a reference system).
> 
> Benchmarking results can be affected by the underlying operating
> system, as well as the Java Virtual Machine.  It could be that you
> saw more garbage collection cycles in one test than another, 
> accountingfor the cumulative second or two.  It could be that the 
> test algorithm
> is sufficiently different to consistently add a second to the test
> time between the different testcases.  Lastly, it could be the
> implementation that is the cause of the delay.
> 
> With the numbers we are talking about (1503 and 1502 seconds), it is
> only a 0.06% increase in time.  The other test (10004 and 10005 sec),
> it is only a 0.01% increase in time.  Hardly worth spending a lot of
> time on it.
> 
> > Between 1,503 and 10,004, and
> > between 1,502 and 10,005 is due to writing 10 time more
> > data in the later case.
> 
> This satisfactorily accounts for the fact that it takes 6.7 times 
> longer.
> > Just one point, in the revolving case first a unique-filename
> > is written, as openFile() is called to early.
> > I have not fixed that, yet, perhaps I can do it before the 
> weekend...> 
> > I'm doing some more tests as you asked me about variance,
> > and now I have following results:
> > Testsuite: 
> org.apache.log.output.test.TestRotatingFileOutputLogTarget> Tests 
> run: 5, Failures: 0, Errors: 0, Time elapsed: 33,489 sec
> > 
> > ------------- Standard Output ---------------
> > File(s) testSizeRotationUniqueFilename.log written: 2270065
> > File(s) testSizeRotationRevolingFilename.log written: 2271565
> > File(s) testTimeRotationUniqueFilename.log written: 15089260
> > File(s) testTimeRotationRevolingFilename.log written: 14864390
> > File(s) testTimeRotationRevolvingFilenameCycles.log written: 
> 15181155> ------------- ---------------- ---------------
> > Testcase: testSizeRotationUniqueFilename took 1,863 sec
> > Testcase: testSizeRotationRevolingFilename took 1,602 sec
> > Testcase: testTimeRotationUniqueFilename took 10,005 sec
> > Testcase: testTimeRotationRevolvingFilename took 10,004 sec
> > Testcase: testTimeRotationRevolvingFilenameCycles took 10,005 sec
> > 
> > What's strange the diff between 1,863 and 1,602
> 
> That's a 16% difference, and categorizes now as significant.  Was
> anything else running in the background when you ran the test?  Was
> that result consistent?
> 
> I realize these take a long time to run, but sometimes the tests
> are more meaningful in averages (i.e. run 10 or more times with the
> results from each run averaged together).
> 
> I also noticed that you have different ammounts of data written in
> each test.  In order to appropriately test you need to make wither
> time constant (run until a set time expires), or the data written
> constant (run until the defined set of data is written).
> 
> <snip-the-old-stuff/>
> 
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