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From Pavel Bortnovskiy <pbortnovs...@jefferies.com>
Subject RE: CPU Utilization
Date Wed, 09 Jan 2013 19:45:23 GMT
Thank you, Kristian, for your quick response.

How can I diagnose this and determine what Derby is doing during the periods of high CPU utilization?
As far as I can determine from watching the log and the "top" simultaneously, it seems that
utilization peeks when data are accessed.
In other words, the query itself seems to run very fast, but accessing the data (with the
JDBC's ResultSet) seems to peek the CPU usage.

P.

From: Kristian Waagan [mailto:kristian.waagan@oracle.com]
Sent: Wednesday, January 09, 2013 2:42 PM
To: derby-user@db.apache.org
Subject: Re: CPU Utilization

On 07.01.2013 20:51, Pavel Bortnovskiy wrote:
Hello:

This is more of a general question. Our application uses Derby in the in-memory mode only.
When the application is configured to use complex queries, such configuration causes CPU utilization
(on the Linux server) to go as high as 300% or even higher. Using simpler queries don't seem
to lead to such high utilization. Is there any way to control or lower CPU utilization by
Derby?

Hi Pavel,

I don't believe there is such a mechanism in place, at least not specifically for the in-memory
back end.

Since this is in-memory, the latency associated with page operations is very low. Do you know
if Derby is using the CPU for something useful (i.e. processing queries effectively), or is
the CPU spent on wasteful activities?
One potential wasteful activity is moving data back and forth from the page cache (page cache
too small?).
Is this a highly concurrent scenario?


Regards,
--
Kristian



Thank you,
Pavel.

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including any attachments, are confidential to the ordinary user of the email address to which
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or otherwise use it or any part of it in any form whatsoever. This email may be produced at
the request of regulators or in connection with civil litigation. Jefferies accepts no liability
for any errors or omissions arising as a result of transmission. Use by other than intended
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