Many people asked me about the second part of my blog title – the mutex. This is the first post about it. Mutexes is another Oracle spinlock, which was appeared in version 10.2.0.2. Despite being known since 2005, Oracle mutex internals is still Terra incognita.
This post is inspired by several recent escalations due to mutex contention. It occurs that 184.108.40.206 patchset contains extraordinary number of mutex related changes. Some enhancements like 10411618 exist only for 220.127.116.11. The following patches even changed the mutex architecture: (more…)