Re: log_checkpoints: count WAL segment creations from all processes

On Wed, Mar 25, 2026 at 9:11 AM Xuneng Zhou <xunengzhou(at)gmail(dot)com> wrote:
>
> Hi Japin,
>
> Thanks for looking into this.
>
> On Tue, Mar 24, 2026 at 10:01 PM Japin Li <japinli(at)hotmail(dot)com> wrote:
> >
> >
> > Hi, Xuneng
> >
> > On Tue, 24 Mar 2026 at 19:17, Xuneng Zhou <xunengzhou(at)gmail(dot)com> wrote:
> > > Hi Zsolt,
> > >
> > > On Tue, Mar 24, 2026 at 1:55 PM Zsolt Parragi <zsolt(dot)parragi(at)percona(dot)com> wrote:
> > >
> > > Hello!
> > >
> > > This is a simple patch, but shouldn't it include at least some basic
> > > tests verifying the new behavior?
> > >
> > > Thanks for looking into this. I've added a test for it. Please take a look.
> >
> > Thanks for updating the patch. A few comments on v2:
> >
> > 1.
> > + (The probes listed next fire in sequence during checkpoint processing.)
> > + arg0 is the number of buffers written. arg1 is the total number of
> >
> > These changes seem unnecessary. Additionally, there appears to be an
> > indentation issue.
>
> Yeah, I've removed these and fixed the indentation issue.
>
> > 2.
> > + current = pg_atomic_read_u64(&XLogCtl->walSegmentsCreated);
> > + CheckpointStats.ckpt_segs_added = (int)
> > + (current - XLogCtl->walSegsCreatedLastCheckpoint);
> > + XLogCtl->walSegsCreatedLastCheckpoint = current;
> >
> > Is integer overflow a concern here? It seems unlikely in practice.
>
> I don’t think overflow is a concern here, but it might still be
> helpful to add some comments to mention it.
>

v4 fixed the inaccurate overflow numbers in comments.

--
Best,
Xuneng