问题描述：
DG standby 不定时CPU消耗达到瓶颈，重启数据库后问题解除吗，由于备库未对外提供任何服务，理论上不应该出现该问题

解决步骤：

在CPU消耗达到瓶颈时查看等待事件

SELECT Sid, Event, P1text, P1, P2text, P2, P3text, P3
FROM V$session_Wait
WHERE Event NOT LIKE '%SQL%'
AND Event NOT LIKE '%rdbms%'
AND Event NOT LIKE '%mon%'
ORDER BY Event;

library cache: mutex X是11g时用来替换之前的library cache latch，主要作用是在hash bucket中定位handle时使用。

[oracle@54-Oracle-Fog-Backup OPatch]$ ./opatch lsinventory
Oracle Interim Patch Installer version 11.2.0.3.0
Copyright (c) 2012, Oracle Corporation.? All rights reserved.
Oracle Home? ? ? : /opt/app/oracle/product/11.2.0/dbhome_1
Central Inventory : /opt/app/oraInventory
? from? ? ? ? ? : /opt/app/oracle/product/11.2.0/dbhome_1/oraInst.loc
OPatch version? ? : 11.2.0.3.0
OUI version? ? ? : 11.2.0.2.0
Log file location : /opt/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-09-17_14-02-19PM_1.log
Lsinventory Output file location : /opt/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/lsinv/lsinventory2015-09-17_14-02-19PM.txt

--------------------------------------------------------------------------------
Installed Top-level Products (1):
Oracle Database 11g? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 11.2.0.2.0
There are 1 products installed in this Oracle Home.
There are no Interim patches installed in this Oracle Home
--------------------------------------------------------------------------------
OPatch succeeded.
?
[oracle@54-Oracle-Fog-Backup OPatch]$ ./opatch prereq CheckConflictAgainstOHWithDetail -phBaseDir /home/oracle/14727315/
Oracle Interim Patch Installer version 11.2.0.3.0
Copyright (c) 2012, Oracle Corporation.? All rights reserved.

PREREQ session

Oracle Home? ? ? : /opt/app/oracle/product/11.2.0/dbhome_1
Central Inventory : /opt/app/oraInventory
? from? ? ? ? ? : /opt/app/oracle/product/11.2.0/dbhome_1/oraInst.loc
OPatch version? ? : 11.2.0.3.0
OUI version? ? ? : 11.2.0.2.0
Log file location : /opt/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-09-17_14-04-14PM_1.log
Invoking prereq "checkconflictagainstohwithdetail"
Prereq "checkConflictAgainstOHWithDetail" passed.
OPatch succeeded.

[oracle@54-Oracle-Fog-Backup OPatch]$ ./opatch apply
Oracle Interim Patch Installer version 11.2.0.3.0
Copyright (c) 2012, Oracle Corporation.? All rights reserved.

Oracle Home? ? ? : /opt/app/oracle/product/11.2.0/dbhome_1
Central Inventory : /opt/app/oraInventory
? from? ? ? ? ? : /opt/app/oracle/product/11.2.0/dbhome_1/oraInst.loc
OPatch version? ? : 11.2.0.3.0
OUI version? ? ? : 11.2.0.2.0
Log file location : /opt/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-09-17_14-04-34PM_1.log