Re: BUG #18165: Could not duplicate handle for "Global/PostgreSQL.xxxxxxxxxx": Bad file descriptor

Hi,

On 2023-10-20 18:16:04 -0400, Tom Lane wrote:
> PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> > Could not duplicate handle for "Global/PostgreSQL.xxxxxxxxxx": Bad file
> > descriptor
>
> That must be coming from dsm_impl_pin_segment or dsm_impl_unpin_segment;
> noplace else has the same error message spelling.
>
> > Error started after a pg_upgrade from 11.17 to 14.9 on the same physical
> > servers.
>
> Both those messages predate v11, so it's hard to tell what changed.
> Are you sure the OS environment didn't change too?

Hm. The first failing query in the log queries pg_catalog.pg_get_keywords(),
which uses record types, makes me suspect that the use of dsms is triggered by
the shared typmod registry. However, the shared typmod registry already exists
in 11 and the query should be way too cheap to trigger use of parallel
query. But once we started using the registry I think we continue using it for
the rest of the lifetime of the backend.

I guess we might now parallelize queries that we didn't in 11 and thus it's
more likely that we end up needing the typmod registry?

Greetings,

Andres Freund