Re: almost-super-user problems that we haven't fixed yet

On Wed, Jan 18, 2023 at 02:51:38PM -0500, Robert Haas wrote:
> Should (nfree < SuperuserReservedBackends) be using <=, or am I confused?

I believe < is correct. At this point, the new backend will have already
claimed a proc struct, so if the number of remaining free slots equals the
number of reserved slots, it is okay.

> What's the deal with removing "and no new replication connections will
> be accepted" from the documentation? Is the existing documentation
> just wrong? If so, should we fix that first? And maybe delete
> "non-replication" from the error message that says "remaining
> connection slots are reserved for non-replication superuser
> connections"? It seems like right now the comments say that
> replication connections are a completely separate pool of connections,
> but the documentation and the error message make it sound otherwise.
> If that's true, then one of them is wrong, and I think it's the
> docs/error message. Or am I just misreading it?

I think you are right. This seems to have been missed in ea92368. I moved
this part to a new patch that should probably be back-patched to v12.

On that note, I wonder if it's worth changing the "sorry, too many clients
already" message to make it clear that max_connections has been reached.
IME some users are confused by this error, and I think it would be less
confusing if it pointed to the parameter that governs the number of
connection slots. I'll create a new thread for this.

--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com