On Tue, 2007-09-11 at 10:21 -0400, Tom Lane wrote:
> Simon Riggs <simon@2ndquadrant.com> writes:
> > 1. The ProcArrayLock is acquired Exclusive-ly by only one remaining
> > operation: XidCacheRemoveRunningXids(). Reducing things to that level is
> > brilliant work, Florian and Tom.
>
> It would be brilliant if it were true, but it isn't. Better look again.
On the more detailed explanation, I say "in normal operation".
My analytical notes attached to the original post show ProcArrayLock is
acquired exclusively during backend start, exit and while making a
prepared (twophase) commit. So yes, it is locked Exclusively in other
places, but they happen rarely and they actually add/remove procs from
the array, so its unlikely anything can change there anyhow.
-- Simon Riggs 2ndQuadrant http://www.2ndQuadrant.com