Horton

Re: make MaxBackends available in _PG_init

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: "Bossart, Nathan" <bossartn@amazon.com>, Robert Haas <robertmhaas@gmail.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: 2022-01-29T05:24:24Z
Lists: pgsql-hackers 
On Fri, Jan 28, 2022 at 08:33:42PM -0800, Nathan Bossart wrote:
> Hm.  Perhaps we should understand the full scope of the problem first.
> What else besides MaxBackends and the shared memory GUCs won't be properly
> initialized when the shared_preload_libraries' _PG_init() functions are
> called?  MaxBackends seems to be the only one that folks have experienced
> problems with, which is why I initially zeroed in on it.

Yeah, it would be good to know the scope before defining the limits
of what could be done.  Another thing may be the interactions with
session_preload_libraries and local_preload_libraries.
--
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