Re: Proposal: Log inability to lock pages during vacuum

On 2014-11-06 19:03:20 -0600, Jim Nasby wrote:
> On 11/6/14, 5:40 PM, Greg Stark wrote:
> >On Thu, Nov 6, 2014 at 9:30 PM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> >>I think the retry logical is a largely pointless complication of already
> >>complex enough code. You're fixing a problem for which there is
> >>absolutely no evidence of its existance. Yes, this happens
> >>occasionally. But it's going to be so absolutely minor in comparison to
> >>just about every other source of bloat.
>
> For some reason I don't have Andres' original email, so I'll reply
> here: I agree with you, and my original proposal was simply to log how
> many pages were skipped, but that was objected to. Simply logging this
> extra information would be a patch of a dozen lines or less.

The objection was that it's unneccessary complexity. So you made the
patch a magnitude more complex *and* added logging? That doesn't make
much sense.

> The problem right now is there's no way to actually obtain evidence
> that this is (or isn't) something to worry about, because we just
> silently skip pages. If we had any kind of tracking on this we could
> stop guessing. :(

What's the worst consequence this could have? A couple pages not marked
all visible and not immediately cleaned up. That's not particularly
harmful.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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