Date: Fri, 6 May 2022 08:27:11 -0700
From: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>,
	Julien Rouhaud <rjuju123@gmail.com>,
	Andres Freund <andres@anarazel.de>,
	Michael Paquier <michael@paquier.xyz>,
	"Bossart, Nathan" <bossartn@amazon.com>,
	Fujii Masao <masao.fujii@oss.nttdata.com>,
	"wangsh.fnst@fujitsu.com" <wangsh.fnst@fujitsu.com>,
	Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>,
	Greg Sabino Mullane <htamfids@gmail.com>,
	"pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Subject: Re: make MaxBackends available in _PG_init
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On Fri, May 06, 2022 at 10:43:21AM -0400, Tom Lane wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> On Fri, May 6, 2022 at 9:57 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> I agree that _PG_fini functions as they stand are worthless.
>>> What I'm not getting is why we should care enough about that
>>> to break just about everybody's extension.  Even if unloading
>>> extensions were feasible, who would bother?
> 
>> Well, if we think that, then we ought to remove the NOT_USED code and
>> all the random _PG_fini() stuff that's still floating around.
> 
> I think that's exactly what we should do, if it bugs you that stuff
> is just sitting there.  I see no prospect that we'll ever make it
> work, because the question of unhooking from hooks is just the tip
> of the iceberg.  As an example, what should happen with any custom
> GUCs the module has defined?  Dropping their values might not be
> very nice, but if we leave them around then the next LOAD (if any)
> will see a conflict.  Another fun question is whether it's ever
> safe to unload a module that was preloaded by the postmaster.
> 
> In short, this seems like a can of very wriggly worms, with not
> a lot of benefit that would ensue from opening it.

+1, I'll put together a new patch set.

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