Re: One PG process eating more than 40GB of RAM and getting killed by OOM

Jean-Christophe Boggio <postgresql(at)thefreecat(dot)org> writes:
> I have no problem disclosing this code and data to the PG dev team (this
> is client data though so please keep it for yourselves). Where can I
> send you a link to the dump ?

Thanks for sending the data. I'm not observing any leak on current
Postgres, and after checking the commit log I realized that your
symptoms look mighty like this previous report:

https://www.postgresql.org/message-id/b2bd02dff61af15e3526293e2771f874cf2a3be7.camel%40cybertec.at

which was fixed here:

Author: Tomas Vondra <tomas(dot)vondra(at)postgresql(dot)org>
Branch: master [98640f960] 2023-07-02 20:03:30 +0200
Branch: REL_16_STABLE Release: REL_16_0 [9ae7b5d1f] 2023-07-02 20:04:16 +0200
Branch: REL_15_STABLE Release: REL_15_4 [0c5fe4ff6] 2023-07-02 20:04:40 +0200
Branch: REL_14_STABLE Release: REL_14_9 [c1affa38c] 2023-07-02 20:05:14 +0200
Branch: REL_13_STABLE Release: REL_13_12 [3ce761d5c] 2023-07-02 20:05:35 +0200

Fix memory leak in Incremental Sort rescans

The Incremental Sort had a couple issues, resulting in leaking memory
during rescans, possibly triggering OOM. The code had a couple of
related flaws:

1. During rescans, the sort states were reset but then also set to NULL
(despite the comment saying otherwise). ExecIncrementalSort then
sees NULL and initializes a new sort state, leaking the memory used
by the old one.

2. Initializing the sort state also automatically rebuilt the info about
presorted keys, leaking the already initialized info. presorted_keys
was also unnecessarily reset to NULL.

Patch by James Coleman, based on patches by Laurenz Albe and Tom Lane.
Backpatch to 13, where Incremental Sort was introduced.

Author: James Coleman, Laurenz Albe, Tom Lane
Reported-by: Laurenz Albe, Zu-Ming Jiang
Backpatch-through: 13
Discussion: https://postgr.es/m/b2bd02dff61af15e3526293e2771f874cf2a3be7.camel%40cybertec.at
Discussion: https://postgr.es/m/db03c582-086d-e7cd-d4a1-3bc722f81765%40inf.ethz.ch

So I think the answer for you is "update to Postgres 14.9".

regards, tom lane