RE: High CPU usage by Oracle

From: Jenkins, Michael <Michael.Jenkins_at_Nextel.com>
Date: Tue, 22 Jan 2002 11:28:40 -0800
Message-ID: <F001.003F7940.20020122111028@fatcity.com>

Here's a Korn Shell script that I use to identify all of the top CPU hogs in Solaris. It is better than "top" because it gives you the actual command that is running:

#!/bin/ksh
# Show the PS version of the top 37 processes (by CPU usage)

print "UID\tPID\tPPID\tSTIME\t\tTIME\tCMD"

top -n 37 2>/dev/null| tail -38 | head -37 | awk '{print $1}' | while read PID
do
  PS=`ps -fp $PID 2>/dev/null| tail -1`

  if [[ `echo $PS | grep -c "UID PID PPID C STIME TTY TIME CMD"` -ne 1 ]]   then
    echo $PS | awk '{for (i = 8; i <= NF; i++) O = O " " $i; print $1 "\t" $2 "\t" $3 "\t" $5 "\t" $7 "\t
" substr(O,2,59)}'
  fi
done

--Michael

-----Original Message-----
Sent: Tuesday, January 22, 2002 1:26 PM
To: Multiple recipients of list ORACLE-L

This query will show current sessions CPU usage. It may indicate a particular session is hogging the CPU.

select

   sess.username,
   stat.sid,
   name.name name,

   sum(stat.value)/100 valuesum_seconds
from v$sesstat stat, v$statname name, v$session sess where

   stat.sid = sess.sid
   and stat.statistic# = name.statistic#    and name.name like '%CPU%'
group by sess.username, stat.sid, name.name;

You should also use 'top' or some similar tool to identify the process.

At times a session may have a 'runaway' process that is hogging the CPU. If a single dedicated server process is using a very high percentage of the CPU, it's would probably be a good idea to kill it. Be sure to identify the user or batch program first to make sure it can be killed.

The output of 'ps -fuoracle' will show a dedicated session as similar to this:

     oracleVDRPROD (DESCRIPTION=(LOCAL=no)(ADDRESS=(PROTOCOL=BEQ)))

The following query will match an
process to an Oracle session:

select

   s.username,
   s.sid,
   s.serial#,
   p.pid ppid,
   s.status,
   s.osuser,

   substr(s.program,1,20) client_program,    s.process client_process,
   substr(p.program,1,20) server_program,    p.spid server_pid
from v$session s, v$process p
where s.username is not null

• use outer join to show sniped sessions in
• v$session that don't have an OS process and p.addr(+) = s.paddr
• uncomment to see only your own session --and userenv('SESSIONID') = s.audsid order by username, sid /

Jared

Uma Mohoni <umohoni_at_ikimbo.com>
Sent by: root_at_fatcity.com
01/22/02 07:20 AM
Please respond to ORACLE-L  

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
        cc: 
        Subject:        High CPU usage by Oracle

Hi,
I would like help with this problem I am grappling with since yesterday. One
of the test boxes with Sun Solaris 2.7 OS and Oracle 8.1.7.2 on it has started showing 97% and above CPU usage mostly by Oracle . It has slowed down the application to a point where the testers can not test. Does any one
have any idea why Oracle would suddenly hog CPU so much? The normal CPU usage on these boxes is 2%-3%. All help is greatly appreciated. Thanks in advance.

Thanks,
Uma Mohoni
Consultant, CDI Corporation
@ iKimbo Inc.
500-A Huntmar Park Drive
Herndon, VA 20170
(703) 904-4150 Ext:237
umohoni_at_ikimbo.com

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  INET: umohoni_at_ikimbo.com

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  INET: Jared.Still_at_radisys.com

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  INET: Michael.Jenkins_at_Nextel.com

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Received on Tue Jan 22 2002 - 13:28:40 CST