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Re: Oracle shadow processes run amok after system clock changed

From: Deborah Lorraine <dlorraine_at_ucdavis.edu>
Date: Wed, 18 Dec 2002 09:45:17 -0800
Message-ID: <F001.0051D232.20021218094517@fatcity.com>


No, this was the middle of the afternoon. Each of those runaway processes were at one time associated with various users in the database doing various tasks, mostly selects. No user complained, so I assume they got detached from their shadow and maybe thought they were logged out? I was surprised that the majority still had inactive database connections.

At 04:08 PM 12/17/2002 -0800, Stephane Faroult wrote:

>Out of the top of my mind, and in the middle of the night : Oracle jobs?
>RECO trying to fix things?
>--

Deborah Lorraine wrote:
>
> For those of you DBA's with a UNIX/SYSADMIN background, what do you think
> of this problem:
>
> For a yet-to-be-explained reason, the system clock on our sun database
> server suddenly changed back 1 hour and 16 minutes sometime around 4 p.m.
> yesterday afternoon. The initial symptoms were that users could not log in
> to the database (we use kerberos for authenticating most user accounts
> which requires an accurate time), and we had an unusually high load average
> of 77! Once we finally figured out the clock was off and the sysadmin
> reset it, the load average did not change even though users could log in
> again. We then noticed 72 (of ~500) oracle processes in the run state, all
> evenly collecting CPU time, although database performance was good.
>
> Some of these 72 processes were orphans and had no database process. Most
> had been doing simple selects, but not a single one was actually active in
> the database. Not all were kerberos-autenticated sessions. The only thing
> these processes had in common is that their process time stamps were in the
> hour period of that questionable time:
>
> oracle 11971 1 2 16:02:28 ? 18:05 oracleprod (LOCAL=NO)
> oracle 13335 1 2 16:19:40 ? 18:19 oracleprod (LOCAL=NO)
> oracle 9911 1 1 15:47:23 ? 18:18 oracleprod (LOCAL=NO)
> ...
>
> After the clock was reset to the correct time, these processes did not
> clear out but when killed, the load returned to normal.
>
> For the most part, Oracle is oblivious to the system clock setting so what
> could have caused the shadow processes to run amok? What could they be
> doing to generate CPU yet doing nothing in the database? Any ideas?
>
> Thanks,
>
> Debi
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Deborah Lorraine
  INET: dlorraine_at_ucdavis.edu

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Received on Wed Dec 18 2002 - 11:45:17 CST

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