Re: Stefan's bug (was: max_standby_delay considered harmful)

On Mon, 2010-05-24 at 09:26 -0400, Robert Haas wrote:
> On Mon, May 24, 2010 at 1:27 AM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> > On Wed, May 19, 2010 at 2:47 PM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> >>>> Oh, right. How about allowing the postmaster only in PM_STARTUP,
> >>>> PM_RECOVERY, PM_HOT_STANDBY or PM_WAIT_READONLY state to invoke
> >>>> walreceiver? We can keep walreceiver alive until all read only
> >>>> backends have gone, and prevent unexpected startup of walreceiver.
> >>>
> >>> Yes, that seems like something we should be checking, if we aren't already.
> >>
> >> I'll do that.
> >
> > Here is the updated version. I added the above-mentioned check
> > into the patch.
>
> This looks pretty reasonable to me, but I guess I feel like it would
> be better to drive the CancelBackup() decision off of whether we've
> ever reached PM_RUN rather than consulting XLogCtl.

That is exactly what XLogCtl tells us and why it is suggested for use.

> It just feels
> cleaner to me to drive all of the postmaster decisions off of the same
> signalling mechanism rather than having a separate one (that only
> works because it's used very late in shutdown when we theoretically
> don't need a lock) just for this one case.
>
> I could be all wet, though.
>
--
Simon Riggs www.2ndQuadrant.com