Re: snapbuild woes

On 2017-05-01 08:46:47 -0400, Tom Lane wrote:
> Noah Misch <noah(at)leadboat(dot)com> writes:
> > On Fri, Apr 21, 2017 at 10:34:58PM -0700, Andres Freund wrote:
> >> ... I was wondering about adding
> >> a loop that simply runs for like 30s and then quits or such, but who
> >> knows.
>
> > If the probabilistic test catches the bug even 5% of the time in typical
> > configurations, the buildfarm will rapidly identify any regression. I'd
> > choose a 7s test that detects the bug 5% of the time over a 30s test that
> > detects it 99% of the time. (When I wrote src/bin/pgbench/t/001_pgbench.pl
> > for a probabilistic bug, I sized that test to finish in 1s and catch its bug
> > half the time. In its case, only two buildfarm members were able to
> > demonstrate the original bug, so 5% detection would have been too low.)
>
> 30sec is kind of a big lump from a buildfarm standpoint, especially if
> you mean "it runs for 30s on my honkin' fast workstation". I'm fine
> with individual tests that run for ~ 1sec.

I was more thinking of pgench -T$XX, rather than constant number of
iterations. I currently can reproduce the issues within like 3-4
minutes, so 5s is probably not quite sufficient to get decent coverage.

- Andres