Shulou(Shulou.com)06/01 Report--

Oracle Study-- resmgr:cpu quantum wait event

The "resmgr:cpu quantum" wait event appears in AWR Report:

"resmgr:cpu quantum" wait event:

Refer to the solution of metalink, which is about oracle resource management. The original text is as follows:

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 1596 346281 216968 89.19 Schedulerdb file scattered read 171071 14778 86 3.81 User I/Olog file sync 28575 10810 378 2.78 Commitdb file sequential read 943457 6569 7 1.69 User I/ODB CPU 2133 0.55Cause

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 inNote 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 ('', 'RESOURCE_PLAN','')

Execute dbms_scheduler.set_attribute ('', '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"

Note:

But many users will find that disabling resource planning often doesn't work. You can disable resource scheduling enabled by Oracle by default, and finally resolve the problem by setting the following parameters:

_ resource_manager_always_on = false

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