Horton

Re: make MaxBackends available in _PG_init

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Julien Rouhaud <rjuju123@gmail.com>
Cc: Robert Haas <robertmhaas@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>, Tom Lane <tgl@sss.pgh.pa.us>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Date: 2022-04-12T16:17:23Z
Lists: pgsql-hackers 
On Tue, Apr 12, 2022 at 01:08:35PM +0800, Julien Rouhaud wrote:
> It looks sensible to me, although I think I would apply 0003 before 0002.

Great.

> +   if (process_shared_preload_libraries_in_progress &&
> +       !allow_when_loading_preload_libs)
> +       ereport(ERROR,
> +               (errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
> +                errmsg("cannot change parameters while loading "
> +                       "\"shared_preload_libraries\"")));
> +
> 
> I think the error message should mention at least which GUC is being modified.

My intent was to make it clear that no parameters can be updated while
loading s_p_l, but I agree that we should mention the specific GUC
somewhere.  Maybe this could go in a hint?

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

Commits

  1. Add a new shmem_request_hook hook.

  2. Remove non-functional code for unloading loadable modules.

  3. Fix misleading comments about background worker registration.

  4. Revert the addition of GetMaxBackends() and related stuff.

  5. Fix typo in multixact.c

  6. Reduce more the number of calls to GetMaxBackends()

  7. Remove MaxBackends variable in favor of GetMaxBackends() function.

  8. Fix comments about bgworker registration before MaxBackends initialization

  9. Fix bogus assertion in BootstrapModeMain().

  10. Make sure MaxBackends is always set