Hello,

This fix allows to protect several backends with a global lock during update operations.
It is configurable and by default the global lock is not enabled.
Under rare condition some plugin may lead to deadlocks. Global lock would be enabled to prevent those deadlocks
during critical phases or to limit production impact during investigations.

 I will do some performance measurement with this fix.

https://fedorahosted.org/389/ticket/47936

https://fedorahosted.org/389/attachment/ticket/47936/0001-Ticket-47936-Create-a-global-lock-to-serialize-write.patch

thanks
thierry