Re: bgwriter and checkpoints

On Fri, Aug 12, 2011 at 9:33 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> Yes, they would still need to talk. But the good news is that they
> only actually need to talk once per checkpoint cycle so we can buffer
> them to a certain extent in shared memory to remove the worst part of
> such contention.

Yeah, some kind of special-purpose communication method between the
cleaning scan and the checkpoint process might help, if the lock
contention turns out to be a problem in practice. Then again, maybe
I'm overthinking things: there's zero sign in any profiling I've done
that BgWriterCommLock is even mildly contended, so even worrying about
it at this point might be a waste of time.

> Checkpointing needs a little more time in its diary to receive those
> messages than it has right now, so there's no easy route.

Yeah.

--
Robert Haas
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