RE: Database using 100% of CPU

In my case, I have a Preproduction environment that is an almost-exact copy of production. The Production server executes this query in about 20 seconds. The PREproduction machine takes 5-6 minutes. I have watched the WinNT 'Perfmon' tool monitor the system.

The query is a full table scan of a view which returns 49245 rows. Not very many. I have exampled the execution plans from Prod and PREprod - they're the same. The tables have all be analyzed recently, and growth is minimal.

When the query is executed, CPU goes to 100% and stays there. The Oracle process (ORACLE.EXE) goes to 100% and stays there. There's a short-duration spike in the disk, and then it settles back down to a negligible state.

There are no jobs running in DBA_JOBS. Matter of fact the job queue is disabled on this server. I 'think' physical memory is OK on this machine; I don't remember at this moment. I don't have any of those cool GIU tools to monitor the database - I'm using SQL and my (often-dim) wits.

I have not looked at the event views yet. Thanks for y'all's help!

Mike

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===========================================================================
Michael P. Vergara
Oracle DBA
Guidant Corporation
(909) 914-2304


-----Original Message-----
Sent: Friday, August 17, 2001 11:18 AM
To: Multiple recipients of list ORACLE-L


It is nt, it is because it is unstable and crashes every 1 second, you just
haven't noticed it.

Seriously though, first verify the processes are oracle and not something
else using task manager.

Then if they are oracle.  Look into v$session and find active sessions.
Trace them back with their sql addresses.

Also look into dba_jobs_running for any running jobs.

I have seen similar problems where a job was scheduled as interval 'sysdate'
which has it run continously right after another, a few of these will do
such a thing.

"Do not criticize someone until you walked a mile in their shoes, that way
when you criticize them, you are a mile a way and have their shoes."

Christopher R. Spence 
Oracle DBA
Phone: (978) 322-5744
Fax:    (707) 885-2275

Fuelspot
73 Princeton Street
North, Chelmsford 01863
 



-----Original Message-----
Sent: Friday, August 17, 2001 1:41 PM
To: Multiple recipients of list ORACLE-L


Steven:

I also have this happen on one of our smaller DBs running NT.  I haven't
found a cause yet either.  Rebooting seems (so far) to be the only cure. If
you get any replies would you please summarize to the list?

Thanx,
Mike

---
===========================================================================
Michael P. Vergara
Oracle DBA
Guidant Corporation
(909) 914-2304


-----Original Message-----
Sent: Friday, August 17, 2001 9:41 AM
To: Multiple recipients of list ORACLE-L


We are having a problem with our database - it is using 100% of the CPU.
This has only started happening recently, and restarting the database
temporarily stops it happening - it usually recurrs a few hours later. There
are no jobs running, and at the moment there are no active connections.
Obviously something has kicked this off, can anyone shed any light on this
or suggest how to find out what is running on the db?


Thanks in advance,

Steven H.

(Oracle 8.1.6.0.0 EE on NT 4 SP5)



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Author: Steven Hovington
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Author: Christopher Spence
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Author: Vergara, Michael (TEM)
  INET: mvergara_at_guidant.com

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