Oracle Study之--resmgr:cpu quantum等待事件

心已赠人 2022-08-05 02:44 240阅读 0赞

**Oracle Study之--resmgr:cpu quantum等待事件**

**在AWR Report中出现“resmgr:cpu quantum”等待事件：**

**![Center][]**

**“resmgr:cpu quantum”等待事件：**

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 on event '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','');`

3. Then, for each window\_name (WINDOW\_NAME from DBA\_SCHEDULER\_WINDOWS), run:

execute dbms\_scheduler.set\_attribute('<window name>','RESOURCE\_PLAN','');

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

##  ##

## References ##

**[NOTE:392037.1][NOTE_392037.1] - Database Hangs. Sessions wait for 'resmgr:cpu quantum'  
[NOTE:756734.1][NOTE_756734.1] - 11g: Scheduler Maintenance Tasks or Autotasks  
[NOTE:786346.1][Note 786346.1] - Resource Manager and Sql Tunning Advisory DEFAULT\_MAINTENANCE\_PLAN  
[NOTE:806893.1][NOTE_806893.1] - Large Waits With The Wait Event "Resmgr:Cpu Quantum"  
注意：**

**但是很多用户会发现禁用资源计划很多时候没有作用.可以禁用Oracle缺省启用的资源调度,最后通过以下参数设置解决问题:  
\_resource\_manager\_always\_on = false**

[Center]: /images/20220805/8c95138533bb4f8bafaae596381fe719.png
[Note 786346.1]: https://support.oracle.com/CSP/main/article?cmd=show&type=NOT&id=786346.1
[NOTE_392037.1]: https://support.oracle.com/CSP/main/article?cmd=show&type=NOT&id=392037.1
[NOTE_756734.1]: https://support.oracle.com/CSP/main/article?cmd=show&type=NOT&id=756734.1
[NOTE_806893.1]: https://support.oracle.com/CSP/main/article?cmd=show&type=NOT&id=806893.1