Re: 011_crash_recovery.pl intermittently fails

At Fri, 05 Mar 2021 13:13:04 +0900 (JST), Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com> wrote in
> At Thu, 04 Mar 2021 23:02:09 -0500, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote in
> > Peter Geoghegan <pg(at)bowt(dot)ie> writes:
> > > On Thu, Mar 4, 2021 at 7:32 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > >> Hmmm ... what environment is that? This test script hasn't changed
> > >> meaningfully in several years, and we have not seen any real issues
> > >> with it up to now.
> >
> > > Did you see this recent thread?
> > > https://postgr.es/m/20210208215206.mqmrnpkaqrdtm7fj@alap3.anarazel.de
> >
> > Hadn't paid much attention at the time, but yeah, it looks like Andres
> > tripped over some variant of this.
> >
> > I'd be kind of inclined to remove this test script altogether, on the
> > grounds that it's wasting cycles on a function that doesn't really
> > do what is claimed (and we should remove the documentation claim, too).
> >
> > Having said that, it's still true that this test has been stable in
> > the buildfarm. Andres explained what he had to perturb to make it
> > fail, so I'm still interested in what Horiguchi-san did to break it.
>
> CONFIGURE = '--enable-debug' '--enable-cassert' '--enable-tap-tests' '--enable-depend' '--enable-nls' '--with-icu' '--with-openssl' '--with-libxml' '--with-uuid=e2fs' '--with-tcl' '--with-llvm' '--prefix=/home/horiguti/bin/pgsql_work' 'LLVM_CONFIG=/usr/bin/llvm-config-64' 'CC=/usr/lib64/ccache/gcc' 'CLANG=/usr/lib64/ccache/clang' 'CFLAGS=-O0' '--with-wal-blocksize=16'
>
> the WAL block size might have affected. I'll recheck without it.

Ok, I don't see the failure. It guess that the WAL records for the
last transaction crosses a block boundary with 8kB WAL blocks, but not
with 16kB blocks.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center