Re: pgsql: Allow Pin/UnpinBuffer to operate in a lockfree manner. - Mailing list pgsql-committers

From Andres Freund
Subject Re: pgsql: Allow Pin/UnpinBuffer to operate in a lockfree manner.
Date
Msg-id 20160418142750.p3qwwnnuacb6n7jw@alap3.anarazel.de
Whole thread Raw
In response to Re: pgsql: Allow Pin/UnpinBuffer to operate in a lockfree manner.  (Alexander Korotkov <a.korotkov@postgrespro.ru>)
Responses Re: pgsql: Allow Pin/UnpinBuffer to operate in a lockfree manner.  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-committers
On 2016-04-18 17:12:32 +0300, Alexander Korotkov wrote:
> On Mon, Apr 18, 2016 at 2:34 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>
> > On Sun, Apr 17, 2016 at 12:01 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > > Andres Freund <andres@anarazel.de> writes:
> > >> Allow Pin/UnpinBuffer to operate in a lockfree manner.
> > >
> > > Now that I've had some occasion to look around in bufmgr.c, I am very
> > > unhappy that there are still boatloads of comments talking about a buffer
> > > header's spinlock, when there is in fact no spinlock anymore.  Please
> > > expend some effort on making this less confusing for the next hacker.
> > > Maybe make those comments talk about a "lock bit" instead?
> >
> > I was actually going to complain about this, too.  I noticed it over
> > the weekend when noodling around with another patch.  I'm not sure
> > exactly how it should be revised, but I find the current state of
> > things confusing.
> >
>
> +1
> Do we have consensus on renaming "buffer header spinlock" to "buffer header
> lock bit"?

Personally I think the "spin" part is actually quite relevant, and I
think we shouldn't loose it. It describes concurrency and blocking
behaviour, and how errors need to be handled (i.e. there may not be
any).

Greetings,

Andres Freund


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