异常等待事件Resmgr:Cpu Quantum导致CPU利用率高

1，系统CPU利用率50%左右，几个会话消耗了大量CPU

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1540 oracle 25 0 2301m 294m 266m R 100.1 0.9 25458:13 oracle
3294 oracle 25 0 2317m 180m 144m R 100.1 0.6 62884:14 oracle
3364 oracle 25 0 2301m 89m 59m R 100.1 0.3 86399:51 oracle
5153 oracle 25 0 2317m 159m 123m R 100.1 0.5 105356:43 oracle
7141 oracle 25 0 2301m 88m 63m R 100.1 0.3 24507:58 oracle
11133 oracle 25 0 2301m 130m 102m R 100.1 0.4 55695:02 oracle
11271 oracle 25 0 2301m 321m 292m R 100.1 1.0 26385:41 oracle
12062 oracle 25 0 2301m 278m 248m R 100.1 0.9 107478:37 oracle
12333 oracle 25 0 2301m 113m 83m R 100.1 0.4 106797:53 oracle
12583 oracle 25 0 2317m 109m 74m R 100.1 0.3 54251:31 oracle
13943 oracle 25 0 2301m 100m 71m R 100.1 0.3 74891:42 oracle
15006 oracle 25 0 2301m 288m 259m R 100.1 0.9 65265:02 oracle
16617 oracle 25 0 2301m 101m 73m R 100.1 0.3 24987:39 oracle
17536 oracle 25 0 2317m 142m 106m R 100.1 0.4 72933:33 oracle
17567 oracle 25 0 2301m 154m 125m R 100.1 0.5 86886:37 oracle
17914 oracle 25 0 2317m 369m 332m R 100.1 1.1 88768:07 oracle
20041 oracle 25 0 2301m 129m 101m R 100.1 0.4 25700:13 oracle


2，异常等待事件resmgr:cpu quantum
12422 0
1227 2401 oracle APPDB 1540 1021 resmgr:cpu quantum 3 12422 0
1298 37025 oracle APPDB 16617 24763 resmgr:cpu quantum 3 12422 0
316 29129 oracle APPDB 21511 2177 resmgr:cpu quantum 3 12422 0
578 41577 oracle APPDB 11271 6989 resmgr:cpu quantum 3 12422 0

3，参考metalink的解决方案，是oracle资源管理方面的问题，原文如下

Symptoms

High waits onevent 'resmgr:cpu quantum' might be noticed even when resource manager is disabled. You already have confirmed parameter RESOURCE_MANAGER_PLAN is set to null but still noticing the above wait events.

Top 5 Timed Foreground Events:

Event                    Waits   Time(s)  Avg wait(ms) % DB time Wait Class
------------------------ ------- -------- ------------ -------------- ---------- -----------
resmgr:cpu quantum         1,596  346,281       216968          89.19 Scheduler
db file scattered read   171,071   14,778           86           3.81 User I/O
log file sync             28,575   10,810          378           2.78 Commit
db file sequential read  943,457   6,569             7           1.69 User I/O
DB CPU                     2,133   0.55

Cause

This could be due to DEFAULT_MAINTENANCE_PLAN. From 11g onwards every weekday window has a pre-defined Resource Plan called DEFAULT_MAINTENANCE_PLAN, which will become active once the related window opens.

Following entries can also be noted in alert log at the time of issue.

Wed Sep 16 02:00:00 2009
Clearing Resource Manager plan via parameter
:
Wed Sep 16 22:00:00 2009
Setting Resource Manager plan SCHEDULER[0x2C55]:DEFAULT_MAINTENANCE_PLAN via scheduler window
Setting Resource Manager plan DEFAULT_MAINTENANCE_PLAN via parameter
Wed Sep 16 22:00:05 2009
Begin automatic SQL Tuning Advisor run for special tuning task "SYS_AUTO_SQL_TUNING_TASK"

Solution

To disable the DEFAULT_MAINTENANCE_PLAN you can use the below steps as suggested in Note 786346.1

1. Set the current resource manager plan to null (or another plan that is not restrictive):

alter system set resource_manager_plan='';


2. Change the active windows to use the null resource manager plan (or other nonrestrictive plan)
using:3. Then, for each window_name (WINDOW_NAME from DBA_SCHEDULER_WINDOWS), run:

execute dbms_scheduler.set_attribute('WEEKNIGHT_WINDOW','RESOURCE_PLAN',''); execute dbms_scheduler.set_attribute('WEEKEND_WINDOW','RESOURCE_PLAN','');


execute dbms_scheduler.set_attribute('<window name>','RESOURCE_PLAN','');


References

NOTE:392037.1 - Database Hangs. Sessions wait for 'resmgr:cpu quantum'
NOTE:756734.1 - 11g: Scheduler Maintenance Tasks or Autotasks
NOTE:786346.1 - Resource Manager and Sql Tunning Advisory DEFAULT_MAINTENANCE_PLAN
NOTE:806893.1 - Large Waits With The Wait Event "Resmgr:Cpu Quantum"