Message-ID: <bfffb132207733e9fbf5fdabe5e36f4f37f39932.camel@cybertec.at>
Subject: Re: Linux OOM killer
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Ariel Tejera <artejera@gmail.com>, pgsql-bugs@lists.postgresql.org
Date: Wed, 02 Oct 2024 06:16:31 +0200
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On Tue, 2024-10-01 at 12:17 -0600, Ariel Tejera wrote:
> Hi.=C2=A0 I hope this message finds you well.
>=20
> The issue is that one of our Postgres servers hit a bug and was killed by=
 linux OOM, as
> shown in the lines below, showing two events:
>=20
> We were able to fix this problem adjusting the server configuration with:
> enable_memoize =3D off
>=20
> Our Postgres version is 14.5=C2=A0
> Linux AWS linux2 (with diverse concurrent workloads)
> Ram 32GB
> Database size 200 GB=C2=A0
>=20
> This is the first reproducible bug I've found in 20 years using postgres,=
 heavily (!)
>=20
> As this bug is associated with large databases, it is impractical to offe=
r a reproducible example for it.
> We hope, however, that this report will be of some use for the Postgres p=
roject.

First of all, update to 14.latest.  I find at least one bug fixed in this a=
rea:
https://postgr.es/c/e4b95b9b02, discussed in https://postgr.es/m/83281eed63=
c74e4f940317186372abfd%40cft.ru

Then, disable memory overcommit, so that you don't get killed by the OOM ki=
ller.
Then you will get an "out of memory" error and a memory context dump in the=
 log.
We'd need to see that to figure out if it really is a bug.

It need not be a bug if you run out of memory.  It might as well be that yo=
u
configured PostgreSQL too generously.

Yours,
Laurenz Albe