Horton

Re: make MaxBackends available in _PG_init

Michael Paquier <michael@paquier.xyz>

View thread View on postgr.es
From: Michael Paquier <michael@paquier.xyz>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>, Nathan Bossart <nathandbossart@gmail.com>, Andres Freund <andres@anarazel.de>, Julien Rouhaud <rjuju123@gmail.com>, "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>
Date: 2022-04-13T07:54:29Z
Lists: pgsql-hackers 
On Tue, Apr 12, 2022 at 05:43:17PM -0400, Tom Lane wrote:
> It probably is.  I'm just offering this as a solution if people want to
> insist on a mechanism to prevent unsafe GUC changes.  If we drop the
> idea of trying to forcibly prevent extensions from Doing It Wrong,
> then we don't need this, only the extra hook.

FWIW, I'd be fine with a simple solution like what Julien has been
proposing with the extra hook, rather than a GUC to enforce all that.
That may be nice in the long-run, but the potential benefits may not
be completely clear, either, after a closer read of this thread.
--
Michael

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