AQ Enqueue / Dequeue Benchmark on RAC 11.1.0.7 Shows Slowdown and Higher CPU
(Doc ID 1105624.1)
Last updated on FEBRUARY 26, 2019
Applies to:
Oracle Database - Enterprise Edition - Version 11.1.0.7 and laterOracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Information in this document applies to any platform.
Symptoms
Performance issue affecting AQ applications where they have upgraded to 11.1.0.7 from 10.2.0.4; AQ activity is centred around enqueue / dequeue activity on a RAC environment.
It should be stated that most application are unlikely to be affected by the issues below .
Main observations :
- performance degradation with RAC is greater than with single instance;
slow down with single instance is also observed;
- commit activity appears to be taking longer;
- higher CPU observed;
- AWR report indicates higher statistic values in relation to the following for
the same test in 11g :
In the library cache activity ( RAC ) section of the AWR reports there is increased activity with respect to the following (same benchmark test) :
| statistic | 10.2.0.4 value | 11.1.0.7 value |
|---|---|---|
| ges pin requests | 192 | 603829 ( TABLE ) |
| ges messages sent | 2423 | 5670 |
| global enqueue gets sync | 1312577 | 2315879 |
| global enqueue releases | 1309834 | 2313511 |
Cause
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In this Document
| Symptoms |
| Cause |
| Solution |
| References |