Horton

Re: make MaxBackends available in _PG_init

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Julien Rouhaud <rjuju123@gmail.com>, 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>, Andres Freund <andres@anarazel.de>, 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: 2022-03-24T20:27:36Z
Lists: pgsql-hackers 
On Thu, Mar 24, 2022 at 4:20 PM Nathan Bossart <nathandbossart@gmail.com> wrote:
> Another possibility could be to add a hook that is called _before_
> _PG_init() where libraries are permitted to adjust GUCs.  After the library
> is loaded, we first call this _PG_change_GUCs() function, then we
> initialize MaxBackends, and then we finally call _PG_init().  This way,
> extensions would have access to MaxBackends within _PG_init(), and if an
> extension really needed to alter GUCs, іt could define this new function.

Yeah, I think this might be better.

-- 
Robert Haas
EDB: http://www.enterprisedb.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