Re: Linux OOM killer

On Tue, 2024-10-01 at 12:17 -0600, Ariel Tejera wrote:
> Hi.  I hope this message finds you well.
>
> 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:
>
> We were able to fix this problem adjusting the server configuration with:
> enable_memoize = off
>
> Our Postgres version is 14.5 
> Linux AWS linux2 (with diverse concurrent workloads)
> Ram 32GB
> Database size 200 GB 
>
> This is the first reproducible bug I've found in 20 years using postgres, heavily (!)
>
> As this bug is associated with large databases, it is impractical to offer a reproducible example for it.
> We hope, however, that this report will be of some use for the Postgres project.

First of all, update to 14.latest.  I find at least one bug fixed in this area:
https://postgr.es/c/e4b95b9b02, discussed in https://postgr.es/m/83281eed63c74e4f940317186372abfd%40cft.ru

Then, disable memory overcommit, so that you don't get killed by the OOM killer.
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 you
configured PostgreSQL too generously.

Yours,
Laurenz Albe