From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Simon Riggs <simon@2ndquadrant.com>, Tomas Vondra <tv@fuzzy.cz>,
        pgsql-committers <pgsql-committers@postgresql.org>,
        Andrew Dunstan <andrew@dunslane.net>
Subject: Re: pgsql: Generational memory allocator
In-reply-to: <20171123193936.fncfnar5wkpx56mw@alap3.anarazel.de>
References: <E1eHa4J-0006hI-Q8@gemulon.postgresql.org>
 <20171123001649.y2nf7422iay6cw3v@alap3.anarazel.de>
 <CANP8+jKoT=Pg5W_3FcKiDf+FMrJhFYacxt_g5E0=tkmb5s8M6g@mail.gmail.com>
 <20171123193936.fncfnar5wkpx56mw@alap3.anarazel.de>
Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Thu, 23 Nov 2017 11:39:36 -0800"
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Date: Thu, 23 Nov 2017 15:06:42 -0500
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Andres Freund <andres@anarazel.de> writes:
> On 2017-11-23 20:57:10 +1100, Simon Riggs wrote:
>> On 23 November 2017 at 11:16, Andres Freund <andres@anarazel.de> wrote:
>>> Looks like it's not quite valgrind clean:
>>> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Dskink&dt=3D2=
017-11-22%2022%3A30%3A01

>> It doesn't report anything useful that would allow me to fix this.

> Uh. It reports a failure, and you can go from there. The error output
> actually is in postmaster.log but for some reason the buildfarm code
> didn't display that in this case.

I think it's a legitimate complaint that postmaster.log wasn't captured
in this failure, but that's a buildfarm script oversight and hardly
Andres' fault.

In any case, valgrind failures are generally easy enough to reproduce
locally.

Meanwhile, over on =

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Dsnapper&dt=3D201=
7-11-23%2013%3A56%3A17

we have

ccache gcc-4.7 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-af=
ter-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security =
-fno-strict-aliasing -fwrapv -fexcess-precision=3Dstandard -g -g -O2 -fsta=
ck-protector --param=3Dssp-buffer-size=3D4 -Wformat -Werror=3Dformat-secur=
ity  -I../../../../src/include  -D_FORTIFY_SOURCE=3D2 -D_GNU_SOURCE -I/usr=
/include/libxml2  -I/usr/include/mit-krb5  -c -o generation.o generation.c
generation.c: In function =E2=80=98GenerationContextCreate=E2=80=99:
generation.c:206:7: error: static assertion failed: "padding calculation i=
n GenerationChunk is wrong"
make[4]: *** [generation.o] Error 1

Looks to me like GenerationChunk imagines that 3*sizeof(pointer)
must be a maxaligned quantity, which is wrong on platforms where
MAXALIGN is bigger than sizeof(pointer).

			regards, tom lane