Re: cache buffer chains contention

Yep,

Using CPU or being re-scheduled by the OS.

Anjo.

"Adams, Matthew (GEA, 088130)" wrote:

>
>
> Would it seem likely for Oracle to be
> doing ANYTHING for a full 30 seconds
> without hitting another wait?
>
> ----
> Matt Adams - GE Appliances - matt.adams_at_appl.ge.com
> Reason is 6/7ths of treason. - The Xtals
>
> -----Original Message-----
> From: Jonathan Lewis [mailto:jonathan_at_jlcomp.demon.co.uk]
> Sent: Wednesday, April 10, 2002 6:54 PM
> To: Multiple recipients of list ORACLE-L
> Subject: Re: cache buffer chains contention
>
>
> seconds_in_wait increments every three seconds,
> so if State is anything other than WAITING the
> column tells you how much time has passed
> since the last wait completed. (Contrary to the
> urban legend that says the value is meaningless).
>
> There are various anomalies and oddities about
> wait events, though, and if you session REALLY
> is doing nothing for 30 seconds, then you've hit
> one; however normally I would say that your
> session is busy doing something (from Oracle's
> perspective) in that 30 seconds.
>
> Jonathan Lewis
> http://www.jlcomp.demon.co.uk
>
> Host to The Co-Operative Oracle Users' FAQ
> http://www.jlcomp.demon.co.uk/faq/ind_faq.html
>
> Author of:
> Practical Oracle 8i: Building Efficient Databases
>
> -----Original Message-----
> To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> Date: 10 April 2002 20:56
>
> |Ok, some guru please explain this to me.
> |
> |process is waiting for 'latch free' according to
> |v$session_wait and the value of P2 = 26
> |which is the cache buffer chains latch.
> |(while holding the HW enqueue, with a bunch of
> |processes waiting on HW)
> |
> |State = 'WAITED KNOWN TIME', so I look at
> |WAIT_TIME, which is 2.
> |
> |However, the process does not appear to be doing
> |ANYTHING and the seconds in the SECONDS_IN_WAIT
> |column is increasing! This continues for about
> |30 seconds, when finally it finishes whatever
> |it was doing and allows the next process to
> |grab the HW enqueue
> |
> |Why would SECONDS_IN_WAIT be increasing when it supposed to be
> |done waiting already?
> |
> |
> |
> |----
> |Matt Adams - GE Appliances - matt.adams_at_appl.ge.com
> |Reason is 6/7ths of treason. - The Xtals
> |
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Jonathan Lewis
> INET: jonathan_at_jlcomp.demon.co.uk
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Anjo Kolk
  INET: anjo_at_oraperf.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
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