Re: pgsql: Fix base backup rate limiting in presence of slow i/o

On Thu, Dec 22, 2016 at 11:10 AM, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
wrote:

> On 21 December 2016 at 20:20, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
> > On Wed, Dec 21, 2016 at 6:55 PM, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
> >> basebackup.c: In function ‘throttle’:
> >> basebackup.c:1284:8: warning: variable ‘wait_result’ set but not used
> >> [-Wunused-but-set-variable]
> >> int wait_result;
> >
> > Interesting.
> >
> > ff44fba4 replaced the latch in walsender, which was not backported (of
> > course).
> >
> > But it also added a CHECK_FOR_INTERRUPTS there.
> >
> > 9.4 does not have a CHECK_FOR_INTERRUPTS anywhere near there. Perhaps
> what's
> > really needed is to put one of those in regardless?
> >
>
> Yeah, it seems reasonable that there should be a CHECK_FOR_INTERRUPTS()
> there.
>
> I'm not really familiar with that code, but it looks like the signal
> handler in 9.4 might not set that latch, so throttle() would have to
> rely on setting ImmediateInterruptOK to make the sleep interruptable,
> in which case the wait result would be irrelevant, right?
>

Sorry for the delay in getting back to this. Looking it over again, yes, I
think you are right, and will commit a patch that just removes the check
for result.

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/