Date: Mon, 10 Nov 2025 20:33:06 +0100
From: Michael Banck <mbanck@gmx.net>
To: Alexander Lakhin <exclusion@gmail.com>
Cc: Thomas Munro <thomas.munro@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>,
	Michael Paquier <michael@paquier.xyz>,
	pgsql-hackers@lists.postgresql.org
Subject: Re: GNU/Hurd portability patches
Message-ID: 
 <20251110193306.GV10642@caipicrew.dd-dns.de;lightning.caipicrew.dd-dns.de>
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Archived-At: 
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Precedence: bulk

Hi Alexander,

On Mon, Nov 10, 2025 at 09:00:01PM +0200, Alexander Lakhin wrote:
> Sorry for the delay. I've finally completed a new round of experiments a=
nd
> discovered the following:
=20
[...]

> 12.10.2025 03:42, Thomas Munro wrote:
> > * I wonder about the special code paths for handlers that were already
> > running and happened to be in sigreturn(), or something like that,
> > which I didn't study at all, but it occurred to me that our pqsignal
> > will only block the signal itself while running a handler (since it
> > doesn't specify SA_NODEFER)... so what happens if you block all
> > signals while running each handler by changing
> > sigemptyset(&act.sa_mask) to sigfillset(&act.sa_mask)?
>=20
> Thank you for the suggestion!
>=20
> With this modification:
> @@ -137,7 +140,7 @@ pqsignal(int signo, pqsigfunc func)
>=20
> =A0#if !(defined(WIN32) && defined(FRONTEND))
> =A0=A0=A0=A0=A0=A0=A0 act.sa_handler =3D func;
> -=A0=A0=A0=A0=A0=A0 sigemptyset(&act.sa_mask);
> +=A0=A0=A0=A0=A0=A0 sigfillset(&act.sa_mask);
> =A0=A0=A0=A0=A0=A0=A0 act.sa_flags =3D SA_RESTART;
>=20
> I got 100 iterations passed (12 of them hanged) without that Assert
> triggered.

But those hangs were unrelated to the assert then, right?

> > * I see special code paths for SIGIO and SIGURG that I didn't try to
> > understand, but I wonder what would happen if we s/SIGURG/SIGXCPU/
>=20
> With sed 's/SIGURG/SIGXCPU/' -i src/backend/storage/ipc/waiteventset.c, =
I
> still got:
> !!!wrapper_handler[8401]| postgres_signal_arg: 28565808, PG_NSIG: 33
> TRAP: failed Assert("postgres_signal_arg < PG_NSIG"), File: "pqsignal.c"=
, Line: 94, PID: 8401
> ...
> 2025-11-09 12:51:24.095 GMT postmaster[7282] LOG:=A0 client backend (PID=
 8401) was terminated by signal 6: Aborted
> 2025-11-09 12:51:24.095 GMT postmaster[7282] DETAIL:=A0 Failed process w=
as
> running: UPDATE PKTABLE set ptest2=3D5 where ptest2=3D2;
> ---
>=20
> !!!wrapper_handler[21000]| postgres_signal_arg: 28545040, PG_NSIG: 33
> TRAP: failed Assert("postgres_signal_arg < PG_NSIG"), File: "pqsignal.c"=
, Line: 94, PID: 21000
> ...
> 2025-11-09 13:06:59.458 GMT postmaster[20669] LOG:=A0 client backend (PI=
D 21000) was terminated by signal 6: Aborted
> 2025-11-09 13:06:59.458 GMT postmaster[20669] DETAIL:=A0 Failed process =
was running: UPDATE pvactst SET i =3D i WHERE i < 1000;
> ---
> !!!wrapper_handler[21973]| postgres_signal_arg: 28562608, PG_NSIG: 33
> TRAP: failed Assert("postgres_signal_arg < PG_NSIG"), File: "pqsignal.c"=
, Line: 94, PID: 21973
>=20
> 2025-11-09 14:56:23.955 GMT postmaster[20665] LOG:=A0 client backend (PI=
D 21973) was terminated by signal 6: Aborted
> 2025-11-09 14:56:23.955 GMT postmaster[20665] DETAIL:=A0 Failed process =
was
> running: INSERT INTO pagg_tab_m SELECT i % 30, i % 40, i % 50 FROM
> generate_series(0, 2999) i;
>=20
> The failure rate is approximately 1 per 30 runs.

Is that the same failure rate you got before?


Michael