異常等待事件Resmgr:Cpu Quantum導致CPU利用率高

n-lauren發表於2014-10-25
事件
1，系統CPU利用率50%左右，幾個會話消耗了大量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，異常等待事件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
   
   
   

3，參考metalink的解決方案，是oracle資源管理方面的問題，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 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"

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