public inbox for [email protected]
help / color / mirror / Atom feedBUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending
5+ messages / 4 participants
[nested] [flat]
* BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending
@ 2023-10-16 09:00 PG Bug reporting form <[email protected]>
2026-05-12 20:00 ` Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending Alexander Lakhin <[email protected]>
0 siblings, 1 reply; 5+ messages in thread
From: PG Bug reporting form @ 2023-10-16 09:00 UTC (permalink / raw)
To: [email protected]; +Cc: [email protected]
The following bug has been logged on the website:
Bug reference: 18158
Logged by: Alexander Lakhin
Email address: [email protected]
PostgreSQL version: 16.0
Operating system: Ubuntu 22.04
Description:
When running check-world in a loop on a rather slow device, I observed
an interesting case. All tests passed successfully, but in the system
journal I found a message about postgres crash during the run.
I reproduced the issue and found in src/test/recovery/tmp_check/log/
012_subtransactions_primary.log:
TRAP: failed Assert("!pgStatLocal.shmem->is_shutdown"), File: "pgstat.c",
Line: 616, PID: 23770
My analysis shows that this Assert failed in a backend (walsender, in my
case) when it has pending stats entries on a server shutdown.
In absence of such entries pgstat_report_stats() exits before the Assert:
/* Don't expend a clock check if nothing to do */
if (dlist_is_empty(&pgStatPending) &&
!have_iostats &&
!have_slrustats &&
!pgstat_have_pending_wal())
{
Assert(pending_since == 0);
return 0;
}
/*
* There should never be stats to report once stats are shut down. Can't
* assert that before the checks above, as there is an unconditional
* pgstat_report_stat() call in pgstat_shutdown_hook() - which at least
* the process that ran pgstat_before_server_shutdown() will still call.
*/
Assert(!pgStatLocal.shmem->is_shutdown);
With the following modification in pgstat_flush_pending_entries():
+if (nowait && (rand() % 10 == 0))
+ did_flush = false;
+else
+{
did_flush = kind_info->flush_pending_cb(entry_ref, nowait);
+}
the issue reproduced easily:
make -s check -C src/test/recovery/ PROVE_TESTS="t/012_subtransactions.pl"
grep TRAP -r src/test/recovery/tmp_check/log
# +++ tap check in src/test/recovery +++
t/012_subtransactions.pl .. ok
All tests successful.
Files=1, Tests=12, 3 wallclock secs ( 0.01 usr 0.00 sys + 0.19 cusr 0.27
csys = 0.47 CPU)
Result: PASS
src/test/recovery/tmp_check/log/012_subtransactions_primary.log:
TRAP: failed Assert("!pgStatLocal.shmem->is_shutdown"), File: "pgstat.c",
Line: 616, PID: 2410126
The stack trace from the log:
postgres: primary: walsender law [local] streaming
0/3019C78(ExceptionalCondition+0xbb)[0x5616c7b58b89]
postgres: primary: walsender law [local] streaming
0/3019C78(pgstat_report_stat+0xef)[0x5616c7991ff1]
postgres: primary: walsender law [local] streaming
0/3019C78(+0x6a9e57)[0x5616c7991e57]
postgres: primary: walsender law [local] streaming
0/3019C78(shmem_exit+0xa6)[0x5616c792d852]
postgres: primary: walsender law [local] streaming
0/3019C78(+0x6456f6)[0x5616c792d6f6]
postgres: primary: walsender law [local] streaming
0/3019C78(proc_exit+0x19)[0x5616c792d63a]
postgres: primary: walsender law [local] streaming
0/3019C78(+0x607cec)[0x5616c78efcec]
postgres: primary: walsender law [local] streaming
0/3019C78(+0x606e47)[0x5616c78eee47]
postgres: primary: walsender law [local] streaming
0/3019C78(+0x6043c8)[0x5616c78ec3c8]
postgres: primary: walsender law [local] streaming
0/3019C78(exec_replication_command+0x4cc)[0x5616c78edfa5]
postgres: primary: walsender law [local] streaming
0/3019C78(PostgresMain+0x7df)[0x5616c796d54b]
...
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending
2023-10-16 09:00 BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending PG Bug reporting form <[email protected]>
@ 2026-05-12 20:00 ` Alexander Lakhin <[email protected]>
2026-05-13 00:46 ` Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending Xuneng Zhou <[email protected]>
0 siblings, 1 reply; 5+ messages in thread
From: Alexander Lakhin @ 2026-05-12 20:00 UTC (permalink / raw)
To: [email protected]
Hello hackers,
16.10.2023 12:00, PG Bug reporting form wrote:
> The following bug has been logged on the website:
>
> Bug reference: 18158
> Logged by: Alexander Lakhin
> Email address:[email protected]
> PostgreSQL version: 16.0
> Operating system: Ubuntu 22.04
> Description:
> ...
> With the following modification in pgstat_flush_pending_entries():
> +if (nowait && (rand() % 10 == 0))
> + did_flush = false;
> +else
> +{
> did_flush = kind_info->flush_pending_cb(entry_ref, nowait);
> +}
>
> the issue reproduced easily:
> make -s check -C src/test/recovery/ PROVE_TESTS="t/012_subtransactions.pl"
> grep TRAP -r src/test/recovery/tmp_check/log
>
> # +++ tap check in src/test/recovery +++
> t/012_subtransactions.pl .. ok
> All tests successful.
> Files=1, Tests=12, 3 wallclock secs ( 0.01 usr 0.00 sys + 0.19 cusr 0.27
> csys = 0.47 CPU)
> Result: PASS
> src/test/recovery/tmp_check/log/012_subtransactions_primary.log:
> TRAP: failed Assert("!pgStatLocal.shmem->is_shutdown"), File: "pgstat.c",
> Line: 616, PID: 2410126
It looks like skink produced this failure yesterday [1]:
241/316 recovery - postgresql:recovery/027_stream_regress ERROR 4374.08s exit status 1
...
stderr:
# Failed test 'check contents of pg_stat_statements on regression database'
# at /home/bf/bf-build/skink/REL_17_STABLE/pgsql/src/test/recovery/t/027_stream_regress.pl line 177.
# got: 'CREATE|f
# SELECT|t'
# expected: 'CREATE|t
# DELETE|t
# INSERT|t
# SELECT|t
# UPDATE|t'
# Looks like you failed 1 test of 9.
pgsql.build/testrun/recovery/027_stream_regress/log/027_stream_regress_primary.log
2026-05-11 14:09:34.397 CEST [4064132][walsender][40/0:0] LOG: released physical replication slot "standby_1"
TRAP: failed Assert("!pgStatLocal.shmem->is_shutdown"), File: "../pgsql/src/backend/utils/activity/pgstat.c", Line: 612,
PID: 4064132
postgres: primary: walsender bf [local] streaming 0/15B4FC98(ExceptionalCondition+0x5f) [0x45ae268]
postgres: primary: walsender bf [local] streaming 0/15B4FC98(pgstat_report_stat+0x14d) [0x4492fe2]
postgres: primary: walsender bf [local] streaming 0/15B4FC98(+0x49315c) [0x449315c]
postgres: primary: walsender bf [local] streaming 0/15B4FC98(shmem_exit+0x78) [0x4448f00]
postgres: primary: walsender bf [local] streaming 0/15B4FC98(+0x449020) [0x4449020]
postgres: primary: walsender bf [local] streaming 0/15B4FC98(proc_exit+0x22) [0x44490c1]
postgres: primary: walsender bf [local] streaming 0/15B4FC98(+0x3f5dbd) [0x43f5dbd]
...
2026-05-11 14:09:34.629 CEST [4063470][postmaster][:0] LOG: server process (PID 4064132) was terminated by signal 6:
Aborted
2026-05-11 14:09:34.629 CEST [4063470][postmaster][:0] DETAIL: Failed process was running: START_REPLICATION SLOT
"standby_1" 0/3000000 TIMELINE 1
2026-05-11 14:09:34.631 CEST [4063470][postmaster][:0] LOG: terminating any other active server processes
And perhaps (I can't find the full log now) one year ago [2]:
227/305 postgresql:recovery / recovery/027_stream_regress ERROR 3364.50s exit status 1
[01:19:39.781](0.108s) not ok 9 - check contents of pg_stat_statements on regression database
[01:19:39.781](0.000s) # Failed test 'check contents of pg_stat_statements on regression database'
# at /home/bf/bf-build/skink/REL_17_STABLE/pgsql/src/test/recovery/t/027_stream_regress.pl line 173.
[01:19:39.781](0.000s) # got: 'CREATE|f
# SELECT|t'
# expected: 'CREATE|t
# DELETE|t
# INSERT|t
# SELECT|t
# UPDATE|t'
I've reproduced such failures with the above modification applied, just
running:
for i in {1..20}; do PROVE_TESTS="t/027*" make -s check -C src/test/recovery/ || break; done
Reproduced on REL_17_STABLE and REL_16_STABLE (starting from dd8008e8e,
which updated 027_stream_regress.pl).
Not reproduced on REL_18_STABLE after 87a6690cc (coming from [3]).
[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2026-05-11%2010%3A25%3A22
[2] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2025-03-18%2023%3A39%3A44
[3] https://www.postgresql.org/message-id/yegnemsijlrhocsfgs7gs7irnczjgkom6fmk2a5u2b66pbvzwi%40ph2h3wppc...
Best regards,
Alexander
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending
2023-10-16 09:00 BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending PG Bug reporting form <[email protected]>
2026-05-12 20:00 ` Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending Alexander Lakhin <[email protected]>
@ 2026-05-13 00:46 ` Xuneng Zhou <[email protected]>
2026-05-13 06:55 ` Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending Michael Paquier <[email protected]>
0 siblings, 1 reply; 5+ messages in thread
From: Xuneng Zhou @ 2026-05-13 00:46 UTC (permalink / raw)
To: Alexander Lakhin <[email protected]>; +Cc: [email protected]
Hi Alexander,
On Wed, May 13, 2026 at 4:00 AM Alexander Lakhin <[email protected]> wrote:
>
> Hello hackers,
>
> 16.10.2023 12:00, PG Bug reporting form wrote:
>
> The following bug has been logged on the website:
>
> Bug reference: 18158
> Logged by: Alexander Lakhin
> Email address: [email protected]
> PostgreSQL version: 16.0
> Operating system: Ubuntu 22.04
> Description:
> ...
> With the following modification in pgstat_flush_pending_entries():
> +if (nowait && (rand() % 10 == 0))
> + did_flush = false;
> +else
> +{
> did_flush = kind_info->flush_pending_cb(entry_ref, nowait);
> +}
>
> the issue reproduced easily:
> make -s check -C src/test/recovery/ PROVE_TESTS="t/012_subtransactions.pl"
> grep TRAP -r src/test/recovery/tmp_check/log
>
> # +++ tap check in src/test/recovery +++
> t/012_subtransactions.pl .. ok
> All tests successful.
> Files=1, Tests=12, 3 wallclock secs ( 0.01 usr 0.00 sys + 0.19 cusr 0.27
> csys = 0.47 CPU)
> Result: PASS
> src/test/recovery/tmp_check/log/012_subtransactions_primary.log:
> TRAP: failed Assert("!pgStatLocal.shmem->is_shutdown"), File: "pgstat.c",
> Line: 616, PID: 2410126
>
>
> It looks like skink produced this failure yesterday [1]:
> 241/316 recovery - postgresql:recovery/027_stream_regress ERROR 4374.08s exit status 1
> ...
> stderr:
> # Failed test 'check contents of pg_stat_statements on regression database'
> # at /home/bf/bf-build/skink/REL_17_STABLE/pgsql/src/test/recovery/t/027_stream_regress.pl line 177.
> # got: 'CREATE|f
> # SELECT|t'
> # expected: 'CREATE|t
> # DELETE|t
> # INSERT|t
> # SELECT|t
> # UPDATE|t'
> # Looks like you failed 1 test of 9.
>
> pgsql.build/testrun/recovery/027_stream_regress/log/027_stream_regress_primary.log
>
> 2026-05-11 14:09:34.397 CEST [4064132][walsender][40/0:0] LOG: released physical replication slot "standby_1"
> TRAP: failed Assert("!pgStatLocal.shmem->is_shutdown"), File: "../pgsql/src/backend/utils/activity/pgstat.c", Line: 612, PID: 4064132
> postgres: primary: walsender bf [local] streaming 0/15B4FC98(ExceptionalCondition+0x5f) [0x45ae268]
> postgres: primary: walsender bf [local] streaming 0/15B4FC98(pgstat_report_stat+0x14d) [0x4492fe2]
> postgres: primary: walsender bf [local] streaming 0/15B4FC98(+0x49315c) [0x449315c]
> postgres: primary: walsender bf [local] streaming 0/15B4FC98(shmem_exit+0x78) [0x4448f00]
> postgres: primary: walsender bf [local] streaming 0/15B4FC98(+0x449020) [0x4449020]
> postgres: primary: walsender bf [local] streaming 0/15B4FC98(proc_exit+0x22) [0x44490c1]
> postgres: primary: walsender bf [local] streaming 0/15B4FC98(+0x3f5dbd) [0x43f5dbd]
> ...
> 2026-05-11 14:09:34.629 CEST [4063470][postmaster][:0] LOG: server process (PID 4064132) was terminated by signal 6: Aborted
> 2026-05-11 14:09:34.629 CEST [4063470][postmaster][:0] DETAIL: Failed process was running: START_REPLICATION SLOT "standby_1" 0/3000000 TIMELINE 1
> 2026-05-11 14:09:34.631 CEST [4063470][postmaster][:0] LOG: terminating any other active server processes
>
> And perhaps (I can't find the full log now) one year ago [2]:
> 227/305 postgresql:recovery / recovery/027_stream_regress ERROR 3364.50s exit status 1
>
> [01:19:39.781](0.108s) not ok 9 - check contents of pg_stat_statements on regression database
> [01:19:39.781](0.000s) # Failed test 'check contents of pg_stat_statements on regression database'
> # at /home/bf/bf-build/skink/REL_17_STABLE/pgsql/src/test/recovery/t/027_stream_regress.pl line 173.
> [01:19:39.781](0.000s) # got: 'CREATE|f
> # SELECT|t'
> # expected: 'CREATE|t
> # DELETE|t
> # INSERT|t
> # SELECT|t
> # UPDATE|t'
>
> I've reproduced such failures with the above modification applied, just
> running:
> for i in {1..20}; do PROVE_TESTS="t/027*" make -s check -C src/test/recovery/ || break; done
>
> Reproduced on REL_17_STABLE and REL_16_STABLE (starting from dd8008e8e,
> which updated 027_stream_regress.pl).
>
> Not reproduced on REL_18_STABLE after 87a6690cc (coming from [3]).
>
> [1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2026-05-11%2010%3A25%3A22
> [2] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2025-03-18%2023%3A39%3A44
> [3] https://www.postgresql.org/message-id/yegnemsijlrhocsfgs7gs7irnczjgkom6fmk2a5u2b66pbvzwi%40ph2h3wppc...
>
> Best regards,
> Alexander
Thanks for reporting this. It appears like backpatching an equivalent
of 87a6690cc69 to REL_17/REL_16 would resolve this issue.
--
Regards,
Xuneng Zhou
HighGo Software Co., Ltd.
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending
2023-10-16 09:00 BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending PG Bug reporting form <[email protected]>
2026-05-12 20:00 ` Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending Alexander Lakhin <[email protected]>
2026-05-13 00:46 ` Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending Xuneng Zhou <[email protected]>
@ 2026-05-13 06:55 ` Michael Paquier <[email protected]>
2026-05-14 07:19 ` Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending Xuneng Zhou <[email protected]>
0 siblings, 1 reply; 5+ messages in thread
From: Michael Paquier @ 2026-05-13 06:55 UTC (permalink / raw)
To: Xuneng Zhou <[email protected]>; +Cc: Alexander Lakhin <[email protected]>; [email protected]
On Wed, May 13, 2026 at 08:46:25AM +0800, Xuneng Zhou wrote:
> Thanks for reporting this. It appears like backpatching an equivalent
> of 87a6690cc69 to REL_17/REL_16 would resolve this issue.
FWIW, I fear such a change in the stable branches based on its
invasiveness, particularly because the area of the code dealing with
shutdown sequences has been reworked a lot lately as far as I recall.
I am seriously wondering if we should just let it go and remove the
assertion on v15~v17. It's not perfect, of course, but I value much
more this assertion in terms of any future work that can be done with
pgstats, not in terms of what we could detect for bug fixes.
--
Michael
Attachments:
[application/pgp-signature] signature.asc (833B, 2-signature.asc)
download
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending
2023-10-16 09:00 BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending PG Bug reporting form <[email protected]>
2026-05-12 20:00 ` Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending Alexander Lakhin <[email protected]>
2026-05-13 00:46 ` Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending Xuneng Zhou <[email protected]>
2026-05-13 06:55 ` Re: BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending Michael Paquier <[email protected]>
@ 2026-05-14 07:19 ` Xuneng Zhou <[email protected]>
0 siblings, 0 replies; 5+ messages in thread
From: Xuneng Zhou @ 2026-05-14 07:19 UTC (permalink / raw)
To: Michael Paquier <[email protected]>; +Cc: Alexander Lakhin <[email protected]>; [email protected]
On Wed, May 13, 2026 at 2:55 PM Michael Paquier <[email protected]> wrote:
>
> On Wed, May 13, 2026 at 08:46:25AM +0800, Xuneng Zhou wrote:
> > Thanks for reporting this. It appears like backpatching an equivalent
> > of 87a6690cc69 to REL_17/REL_16 would resolve this issue.
>
> FWIW, I fear such a change in the stable branches based on its
> invasiveness, particularly because the area of the code dealing with
> shutdown sequences has been reworked a lot lately as far as I recall.
>
> I am seriously wondering if we should just let it go and remove the
> assertion on v15~v17. It's not perfect, of course, but I value much
> more this assertion in terms of any future work that can be done with
> pgstats, not in terms of what we could detect for bug fixes.
I agree that applying the change wholesale could be too invasive. If
we decide not to address the ordering issue, removing this assertion
seems reasonable, since the non-assert path does not actually provide
the required guarantee.
--
Regards,
Xuneng Zhou
HighGo Software Co., Ltd.
^ permalink raw reply [nested|flat] 5+ messages in thread
end of thread, other threads:[~2026-05-14 07:19 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2023-10-16 09:00 BUG #18158: Assert in pgstat_report_stat() fails when a backend shutting down with stats pending PG Bug reporting form <[email protected]>
2026-05-12 20:00 ` Alexander Lakhin <[email protected]>
2026-05-13 00:46 ` Xuneng Zhou <[email protected]>
2026-05-13 06:55 ` Michael Paquier <[email protected]>
2026-05-14 07:19 ` Xuneng Zhou <[email protected]>
This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox