Re: Valgrind failures caused by multivariate stats patch

On 2017-03-26 20:38:52 +0200, Tomas Vondra wrote:
> On 03/25/2017 10:10 PM, Andres Freund wrote:
> ...
> > ==2486== Uninitialised byte(s) found during client check request
> > ==2486== at 0x1C4857: printtup (printtup.c:347)
> > ==2486== by 0x401FD5: ExecutePlan (execMain.c:1681)
> > ==2486== by 0x3FFDED: standard_ExecutorRun (execMain.c:355)
> > ==2486== by 0x3FFC07: ExecutorRun (execMain.c:298)
> > ==2486== by 0x5C40BD: PortalRunSelect (pquery.c:928)
> > ==2486== by 0x5C3D50: PortalRun (pquery.c:769)
> > ==2486== by 0x5BDC1A: exec_simple_query (postgres.c:1101)
> > ==2486== by 0x5C203F: PostgresMain (postgres.c:4071)
> > ==2486== by 0x525138: BackendRun (postmaster.c:4317)
> > ==2486== by 0x524848: BackendStartup (postmaster.c:3989)
> > ==2486== by 0x520C4A: ServerLoop (postmaster.c:1729)
> > ==2486== by 0x5201D9: PostmasterMain (postmaster.c:1337)
> > ==2486== by 0x45DFA6: main (main.c:228)
> > ==2486== Address 0x3e8c50f5 is in a rw- anonymous segment
> > ==2486== Uninitialised value was created by a heap allocation
> > ==2486== at 0x76212F: palloc (mcxt.c:872)
> > ==2486== by 0x578814: statext_ndistinct_build (mvdistinct.c:80)
> > ==2486== by 0x577CCE: BuildRelationExtStatistics (extended_stats.c:94)
> > ==2486== by 0x3546B6: do_analyze_rel (analyze.c:577)
> > ==2486== by 0x353B76: analyze_rel (analyze.c:271)
> > ==2486== by 0x3E7B89: vacuum (vacuum.c:321)
> > ==2486== by 0x3E7755: ExecVacuum (vacuum.c:122)
> > ==2486== by 0x5C5F1C: standard_ProcessUtility (utility.c:670)
> > ==2486== by 0x5C5724: ProcessUtility (utility.c:353)
> > ==2486== by 0x5C46CA: PortalRunUtility (pquery.c:1174)
> > ==2486== by 0x5C48D0: PortalRunMulti (pquery.c:1317)
> > ==2486== by 0x5C3E1A: PortalRun (pquery.c:795)
> > ==2486== by 0x5BDC1A: exec_simple_query (postgres.c:1101)
> > ==2486== by 0x5C203F: PostgresMain (postgres.c:4071)
> > ==2486== by 0x525138: BackendRun (postmaster.c:4317)
> > ==2486== by 0x524848: BackendStartup (postmaster.c:3989)
> > ==2486== by 0x520C4A: ServerLoop (postmaster.c:1729)
> > ==2486== by 0x5201D9: PostmasterMain (postmaster.c:1337)
> > ==2486== by 0x45DFA6: main (main.c:228)
>
> Hmmm, so I have a theory about what's going on, but no matter what I do I
> can't trigger these valgrind failures. What switches are you using to start
> valgrind? I'm using this:
>
> valgrind --leak-check=no --undef-value-errors=yes \
> --expensive-definedness-checks=yes --track-origins=yes \
> --read-var-info=yes --gen-suppressions=all \
> --suppressions=src/tools/valgrind.supp --time-stamp=yes \
> --log-file=$HOME/pg-valgrind/%p.log --trace-children=yes \
> postgres --log_line_prefix="%m %p " --log_statement=all \
> --shared_buffers=64MB -D /home/user/tmp/data-valgrind 2>&1

--quiet \
--error-exitcode=55 \
--suppressions=${PG_SRC_DIR}/src/tools/valgrind.supp \
--trace-children=yes --track-origins=yes --read-var-info=yes \
--num-callers=20 \
--leak-check=no \
--gen-suppressions=all \

the error-exitcode makes it a whole lot easier to see an error, because
it triggers a crash-restart cycle at backend exit ;)

Note that skink also finds the issue:
https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=skink&dt=2017-03-26%2013%3A00%3A01&stg=check

Did you compile postgres with valgrind support (-DUSE_VALGRIND / pg_config_manual.h)?

- Andres