Re: pgsql: Teach DSM registry to ERROR if attaching to an uninitialized ent

On Mon, Nov 24, 2025 at 04:02:18PM -0500, Robert Haas wrote:
> I haven't done a full review of this and I'm not sure whether you want
> me to spend more time on it...

I'd appreciate an eyeball check if you have the time.

> I'm guessing that the reason why that doesn't easily work is
> because you're relying on those locks to prevent multiple backends
> from doing the same initialization?

For GetNamedDSMSegment(), I bet we could avoid needing a PG_CATCH by taking
the DSMRegistryLock exclusively when accessing the registry.  But for
GetNamedDSA() and GetNamedDSHash(), we want to keep the half-initialized
entry so that we don't leak LWLock tranche IDs.  I initially thought that
might be okay, but if every backend is retrying, you could quickly run out
of tranche IDs.

-- 
nathan