Re: [BackendXidGetPid] only access allProcs when xid matches

Forgot to attach the patch.

On Thu, Sep 7, 2023 at 1:22 PM Ashutosh Bapat
<ashutosh(dot)bapat(dot)oss(at)gmail(dot)com> wrote:
>
> Hi Junwang,
> We leave a line blank after variable declaration as in the attached patch.
>
> Otherwise the patch looks good to me.
>
> The function modified by the patch is only used by extension
> pgrowlocks. Given that the function will be invoked as many times as
> the number of locked rows in the relation, the patch may show some
> improvement and thus be more compelling. One way to measure
> performance is to create a table with millions of rows, SELECT all
> rows with FOR SHARE/UPDATE clause. Then run pgrowlock() on that
> relation. This will invoke the given function a million times. That
> way we might be able to catch some miniscule improvement per row.
>
> If the performance is measurable, we can mark the CF entry as ready
> for committer.
>
> --
> Best Wishes,
> Ashutosh Bapat
>
> On Thu, Aug 10, 2023 at 1:48 PM Junwang Zhao <zhjwpku(at)gmail(dot)com> wrote:
> >
> > On Thu, Aug 10, 2023 at 4:11 PM Ashutosh Bapat
> > <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com> wrote:
> > >
> > > Please add this to commitfest so that it's not forgotten.
> > >
> >
> > Added [1], thanks
> >
> > [1]: https://commitfest.postgresql.org/44/4495/
> >
> > > On Wed, Aug 9, 2023 at 8:37 PM Junwang Zhao <zhjwpku(at)gmail(dot)com> wrote:
> > > >
> > > > On Wed, Aug 9, 2023 at 10:46 PM Ashutosh Bapat
> > > > <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com> wrote:
> > > > >
> > > > > On Wed, Aug 9, 2023 at 9:30 AM Junwang Zhao <zhjwpku(at)gmail(dot)com> wrote:
> > > > > >
> > > > > > In function `BackendXidGetPid`, when looping every proc's
> > > > > > TransactionId, there is no need to access its PGPROC since there
> > > > > > is shared memory access: `arrayP->pgprocnos[index]`.
> > > > > >
> > > > > > Though the compiler can optimize this kind of inefficiency, I
> > > > > > believe we should ship with better code.
> > > > > >
> > > > >
> > > > > Looks good to me. However, I would just move the variable declaration
> > > > > with their assignments inside the if () rather than combing the
> > > > > expressions. It more readable that way.
> > > >
> > > > yeah, make sense, also checked elsewhere using the original style,
> > > > attachment file
> > > > keep that style, thanks ;)
> > > >
> > > > >
> > > > > --
> > > > > Best Wishes,
> > > > > Ashutosh Bapat
> > > >
> > > >
> > > >
> > > > --
> > > > Regards
> > > > Junwang Zhao
> > >
> > >
> > >
> > > --
> > > Best Wishes,
> > > Ashutosh Bapat
> >
> >
> >
> > --
> > Regards
> > Junwang Zhao

--
Best Wishes,
Ashutosh Bapat