Excerpts from Jay Pipes's message of 2015-02-09 12:36:45 -0800: > CAS is preferred because it is measurably faster and more > obstruction-free than SELECT FOR UPDATE. A colleague of mine is almost > ready to publish documentation showing a benchmark of this that shows > nearly a 100% decrease in total amount of lock/wait time using CAS > versus waiting for the coarser-level certification timeout to retry the > transactions. As mentioned above, I believe this is due to the dramatic > decrease in ROLLBACKs. >
I think the missing piece of the puzzle for me was that each ROLLBACK is an expensive operation. I figured it was like a non-local return (i.e. 'raise' in python or 'throw' in java) and thus not measurably different. But now that I think of it, there is likely quite a bit of optimization around the query path, and not so much around the rollback path. The bottom of this rabbit hole is simply exquisite, isn't it? :) __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
