Re: /proc/self/oom_adj is deprecated in newer Linux kernels

In short:

I can accept the idea that picking reasonable specific values is impossible
so let's just ensure that children are always killed before the parent
(basically the default behavior). If you then say that any system that is
capable of implementing that rule should have it set then leaving it
unexposed makes sense. That line of thought does not require the abstract
cost of a GUC to factor into the equation.

However, in considering system configuration and concurrently running
processes....

Tom Lane-2 wrote
> Extra GUCs do not have zero cost, especially not ones that are as
> complicated-to-explain as this would be.

The explain factor does little for me since if given a reasonable default
the GUC can be ignored until a problem manifests. At that point not having
a GUC makes resolving the problem require someone to stop using packaging
and instead compile their own source. This results in a poor user
experience.

So, if someone where to provide a complete patch that introduced a GUC to
enable/disable as well as set priorities - to include documentation and
reasonable postgresql.conf defaults - what specific ongoing GUC costs would
prevent applying said patch?

You mention a security hazard but that is not a cost of GUCs generally but
this one specifically; and one that seems to have been deemed no riskier
than other DBA capabilities.

Help me understand the cost side of the equation since the benefit side
seems clear-cut enough to me. The OOM problem is real and making PostgreSQL
fit within the overall memory management architecture of a given server is
something that is the responsibility of the system admin in conjunction with
the DBA - not us or the packager. I'll buy that because this is a linux
issue that the implementation could be packager selectable but given the
dynamics of Linux centralizing a reasonable default implementation into core
makes sense.

David J.

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