Hi ALL, Snip from CreateCheckPoint(): -- /* * Acquire CheckpointLock to ensure only one checkpoint happens at a time. * (This is just pro forma, since in the present system structure there is * only one process that is allowed to issue checkpoints at any given * time.) */ LWLockAcquire(CheckpointLock, LW_EXCLUSIVE); --
As per this comment, it seems to be that we don't really need this LW lock. We could have something else instead if we are afraid of having multiple checkpoints at any given time which isn't possible, btw. This CheckpointLock is acquired almost at the start of CreateCheckPoint() and released at the end. The in-between code can take a while to be complete. All that time interrupt will be on hold which doesn't seem to be a great idea but that wasn't problematic until now. I am having trouble due to this interrupt hold for a long since I was trying to add code changes where the checkpointer process is suppose to respond to the system read-write state change request as soon as possible[1]. That cannot be done if the interrupt is disabled since read-write state change uses the global barrier mechanism to convey system state changes to other running processes. So my question is, can we completely get rid of the CheckpointLock need in CreateCheckPoint()? Thoughts/Comments/Suggestions? Thank you! Regards, Amul 1]http://postgr.es/m/CA+TgmoYexwDQjdd1=15KMz+7VfHVx8VHNL2qjRRK92P=csz...@mail.gmail.com
