Mutex waits. Part III. Contemporary Oracle wait schemes diversity.

Several months have passed since my previous “mutex wait” post. I was so busy with work and conference presentations. Thanks to all my listeners at UKOUG2011, Hotsos2012 and Medias2012 conferences and several seminars for inspiring questions and conversations.

I. Unexpected change.

Now it is time to discuss how contemporary Oracle waits for mutexes. My previous posts described evolution of “invisible and aggressive” 10.2-11.1 mutex waits into fully accounted and less aggressive 11gR2 mutexes. Surprisingly Oracle 11.2.0.2.2 (or 11.2.0.2 PSU2) appeared in April 2011 demonstrated almost negligible CPU consumption during mutex waits.