Re: CPU Wait troubleshoot

From: Jeff Chirco <backseatdba_at_gmail.com>
Date: Tue, 12 Apr 2016 17:09:02 -0700
Message-ID: <CAKsxbLo3fc1529CPuwJfbuL8mQ+k5fZjQ2B2VL8ZSA6oVMM8yg_at_mail.gmail.com>

No parallelism on this. And ASH does not show this number active sessions, it only shows 4.

On Tue, Apr 12, 2016 at 12:17 PM, Powell, Mark <mark.powell2_at_hpe.com> wrote:

> Is PQO in use on your system? The submission of a query which
> gets/demands a very high degree of parallelism can cause a spike in CPU
> while the query slaves are launched and running.
>
>
>
> What does the ASH report show for this time period? If the information is
> anywhere I would think this is the place to look.
>
>
>
>
>
> *From:* oracle-l-bounce_at_freelists.org [mailto:
> oracle-l-bounce_at_freelists.org] *On Behalf Of *Martin Berger
> *Sent:* Tuesday, April 12, 2016 1:41 PM
> *To:* backseatdba_at_gmail.com
> *Cc:* oracle-l_at_freelists.org
> *Subject:* Re: CPU Wait troubleshoot
>
>
>
> Jeff,
> Spikes in graphs which show averages are ... dangerous.
> But nevertheless you should be able to identify "something" those sessions
> have in common.
> My first checks are sql_id, or program/action/module/... (your application
> is properly instrumented?)
> or in general anything you can use to identify why these sessions are
> special, especially in comparison to the "ordinary" 2-5 active sessions.
>
> If you find anything special in those sessions, we all together can drill
> down to explain what's going on in your system.
>
> Martin
>
>
>
> 2016-04-12 19:16 GMT+02:00 Jeff Chirco <backseatdba_at_gmail.com>:
>
> Looking for some help on how to troubleshoot this spike in CPU Wait.
> Every so often it will see this large spike and I am not sure how to find
> out what it is related to or why it is happening. It spike up to 400 active
> sessions when normally we only around 2 - 5. When I click on the graph to
> drill in it only show the CPU usage and nothing near 400 active sessions.
> What else do I need to look out to figure this out. Thanks in advanced.
>
>
> [image: Inline image 1]
>
> Jeff
>
>
>
>
>
> --
>
> Martin Berger martin.a.berger_at_gmail.com
> +43 660 660 83306 <+4366066083306>
> _at_martinberx <https://twitter.com/martinberx>
> http://berxblog.blogspot.com
>

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Received on Wed Apr 13 2016 - 02:09:02 CEST