Re: make MaxBackends available in _PG_init

Nathan Bossart <bossartn@amazon.com>

From: "Bossart, Nathan" <bossartn@amazon.com>
To: Fujii Masao <masao.fujii@oss.nttdata.com>, "wangsh.fnst@fujitsu.com" <wangsh.fnst@fujitsu.com>
Cc: Robert Haas <robertmhaas@gmail.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: 2022-01-07T20:20:02Z
Lists: pgsql-hackers

Attachments

On 1/7/22, 10:12 AM, "Bossart, Nathan" <bossartn@amazon.com> wrote:
> While that approach would provide a way to safely retrieve the value,
> I think it would do little to prevent the issue in practice.  If the
> size of the patch is a concern, we could also convert MaxBackends into
> a macro for calling GetMaxBackends().  This could also be a nice way
> to avoid breaking extensions that are using it correctly while
> triggering ERRORs for extensions that are using it incorrectly.  I've
> attached a new version of the patch that does it this way.

v5 didn't work with EXEC_BACKEND.  Here is a new revision.

Nathan

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