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RE: cache buffer chains contention

From: Adams, Matthew (GEA, 088130) <MATT.ADAMS_at_APPL.GE.COM>
Date: Thu, 11 Apr 2002 08:01:40 -0800
Message-ID: <F001.00441DFC.20020411080140@fatcity.com>


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-----
Sent: Wednesday, April 10, 2002 6:54 PM
To: Multiple recipients of list ORACLE-L

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: Adams, Matthew (GEA, 088130)
  INET: MATT.ADAMS_at_APPL.GE.COM

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
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To REMOVE yourself from this mailing list, send an E-Mail message
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Received on Thu Apr 11 2002 - 11:01:40 CDT

Original text of this message

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