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High CPU Usage and High Redolog Generation from SMON Process (Doc ID 1569564.1)

Last updated on DECEMBER 29, 2019

Applies to:

Oracle Database - Enterprise Edition - Version 10.2.0.1 to 10.2.0.5 [Release 10.2]
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
***Checked for relevance on 09-Sep-2016***

Symptoms

- High cpu usage and high redolog generation reported by smon.

- Shutdown immediate hangs

- ASH report contains:

Top Sessions

  Sid, Serial# % Activity Event % Event
--------------- ---------- ------------------------------ ----------
User Program # Samples Active XIDs
-------------------- ------------------------------ ------------------ --------
  219, 1 64.52 CPU + Wait for CPU 64.52
SYS oracle@xxxx    (SMON) 3,610/3,615 [100%] 0

  192,28348 1.64 CPU + Wait for CPU 1.52
user xxx.exe 85/3,615 [ 2%] 40

  177,43680 1.59 CPU + Wait for CPU 1.54
user xxx.exe 86/3,615 [ 2%] 44

  221, 1 1.09 log file parallel write 1.04
SYS oracle@xxxx (LGWR) 58/3,615 [ 2%] 0

  88,29672 1.00 db file sequential read 0.61
user xxx.exe 34/3,615 [ 1%] 0

  -------------------------------------------------------------

 
- Alert log shows high redolog:

Fri Jul 05 08:19:56 NZST 2013
Thread 1 advanced to log sequence 378574 (LGWR switch)
  Current log# 2 seq# 378574 mem# 0: /..log2.dbf
Fri Jul 05 08:23:21 NZST 2013
Thread 1 advanced to log sequence 378575 (LGWR switch)
  Current log# 1 seq# 378575 mem# 0: /..log1..dbf
Fri Jul 05 08:26:47 NZST 2013
Thread 1 advanced to log sequence 378576 (LGWR switch)
  Current log# 3 seq# 378576 mem# 0: /.../log3.dbf
Fri Jul 05 08:29:56 NZST 2013
Thread 1 advanced to log sequence 378577 (LGWR switch)
  Current log# 2 seq# 378577 mem# 0: /../log2.dbf
Fri Jul 05 08:34:28 NZST 2013
....
Thread 1 advanced to log sequence 378584 (LGWR switch)
  Current log# 1 seq# 378584 mem# 0: /../log1..dbf
Fri Jul 05 08:58:12 NZST 2013
Thread 1 advanced to log sequence 378585 (LGWR switch)
  Current log# 3 seq# 378585 mem# 0: /../log3..dbf

 

Cause

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In this Document
Symptoms
Cause
Solution


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