Re: pgsql: Generational memory allocator

Andres Freund <andres(at)anarazel(dot)de> writes:
> On 2017-11-23 20:57:10 +1100, Simon Riggs wrote:
>> On 23 November 2017 at 11:16, Andres Freund <andres(at)anarazel(dot)de> wrote:
>>> Looks like it's not quite valgrind clean:
>>> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2017-11-22%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=snapper&dt=2017-11-23%2013%3A56%3A17

we have

ccache gcc-4.7 -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -g -g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -I../../../../src/include -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -I/usr/include/libxml2 -I/usr/include/mit-krb5 -c -o generation.o generation.c
generation.c: In function ‘GenerationContextCreate’:
generation.c:206:7: error: static assertion failed: "padding calculation in 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