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

Hi,

On Fri, Oct 13, 2023 at 03:06:57PM +0200, Jean-Christophe Boggio wrote:
> On my dev laptop, I have ~40GB free RAM. When launching a heavy calculation
> in PostgreSQL (within a stored procedure), it consumes as much memory as is
> available and then gets killed by OOM. There is only one connected session.
>
> I have the following settings, which look reasonable (to me):
>
> shared_buffers = 512MB                  # min 128kB

That's not a lot.

> work_mem = 1GB                          # min 64kB

On the other hand, that's a lot. So if that query is run in parallel and
has a lot of different things it does, it might use work_mem several
times over, resulting in a lot of used memory.

So first thing to try would be to lower work_mem to someting much lower
like 64MB or 128MB.

> This is PostgreSQL 14.7 running on Ubuntu 23.04

The other thing you can try is to see whether turning jit off (or just
jit_inline_above_cost = -1) is helping.

Michael