My Oracle Support Banner

AQ Enqueue / Dequeue Benchmark on RAC 11.1.0.7 Shows Slowdown and Higher CPU (Doc ID 1105624.1)

Last updated on AUGUST 04, 2018

Applies to:

Oracle Database - Enterprise Edition - Version 11.1.0.7 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.

Note : the issue was observed under a benchmark which exibited a slow down of around 20% in enqueue / dequeue performance ; the benchmark was focused specifically on AQ actvity : enqueuing / dequeuing tens of thousands of messages .


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)  :

statistic10.2.0.4 value11.1.0.7 value
ges pin requests 192 603829 ( TABLE )
ges messages sent 2423 5670
global enqueue gets sync 1312577 2315879
global enqueue releases 1309834 2313511

Cause

To view full details, sign in with your My Oracle Support account.

Don't have a My Oracle Support account? Click to get started!

In this Document
Symptoms
Cause
Solution
References


My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.