Oracle Study--RESMGR:CPU Quantum wait event

Oracle Study--RESMGR:CPU Quantum wait event

The "Resmgr:cpu Quantum" wait event appears in the AWR report:

"Resmgr:cpu Quantum" wait event :

Referring to the Metalink solution, Oracle's resource management issues are as follows:

Symptoms

High waits on event ' resmgr:cpu Quantum ' might being noticed even when resource manager is disabled. You already has 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 is due to Default_maintenance_plan. From 11g onwards every weekday Windows has a pre-defined Resource Plan called Default_maintenance_plan, which would become a Ctive Once the related window opens.
Following entries can also be noted on 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]:D Efault_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 your can use the below steps as suggested in Note 786346.1
1. Set the current resource manager plan to null (or another plan this is not restrictive):

alter system set resource_manager_plan=‘‘;

2. Change of 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 -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"
Attention:

However, many users will find that disabling the resource plan is often not useful. You can disable Oracle's default enabled resource scheduling, and finally resolve the issue with the following parameter settings:
_resource_manager_always_on = False

This article is from the "Tianya blog," Please make sure to keep this source http://tiany.blog.51cto.com/513694/1657574

Oracle Study--RESMGR:CPU Quantum wait event