Re: Scaling shared buffer eviction

From: Andres Freund <andres(at)2ndquadrant(dot)com>
To: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Scaling shared buffer eviction
Date: 2014-09-11 13:29:53
Message-ID: 20140911132953.GB17294@awork2.anarazel.de
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> > We really need a more centralized way to handle error cleanup in
> > auxiliary processes. The current state of affairs is really pretty
> > helter-skelter. But for this patch, I think we should aim to mimic
> > the existing style, as ugly as it is. I'm not sure whether Amit's got
> > the logic correct, though: I'd agree LWLockReleaseAll(), at a minimum,
> > is probably a good idea.
>
> Code related to bgreclaimer logic itself doesn't take any LWLock, do
> you suspect the same might be required due to some Signal/Interrupt
> handling?

I suspect it might creep in at some point at some unrelated place. Which
will only ever break in production scenarios. Say, a lwlock in in config
file processing. I seem to recall somebody seing a version of a patching
adding a lwlock there... :). Or a logging hook. Or ...

The savings from not doing LWLockReleaseAll() are nonexistant, so ...

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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