Re: pg_stat_activity crashes

Hello, thank you for understanding.

At Mon, 25 Apr 2016 10:26:49 -0400, Robert Haas <robertmhaas(at)gmail(dot)com> wrote in <CA+TgmoZDcaGCF0n9PaF5kzwj0CNRa-E+tDgzW80GVxg77gPdSA(at)mail(dot)gmail(dot)com>
> On Thu, Apr 21, 2016 at 9:47 PM, Kyotaro HORIGUCHI
> <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> > A lock was already held in BackendPidGetProc(). Is it also
> > needless? If so, we should use BackendPidGetProcWithLock() instad
> > (the name seems a bit confusing, though).
>
> Oh, that's really sad. No, that lock is definitely needed. We should
> probably try to figure out some day if there is a way to make this
> completely lockless, but that'll have to be 9.7 material or later.
> :-(

Agreed.

> > What I did in the patch was just extending the lock duration
> > until reading the pointer proc. I didn't added any additional
> > lock.
>
> Sorry, I didn't realize that. Good point.

I'm happy that you understand me:)

> >> > The
> >> > only thing we need to do is to prevent the value from being read
> >> > twice, and we already have precedent for how to prevent that in
> >> > freelist.c.
> >
> > However, I don't have objections for the patch applied.
>
> OK, let's leave it like that for now, then.

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center