Re: make MaxBackends available in _PG_init

From: Nathan Bossart <nathandbossart(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Julien Rouhaud <rjuju123(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Michael Paquier <michael(at)paquier(dot)xyz>, "Bossart, Nathan" <bossartn(at)amazon(dot)com>, Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com>, "wangsh(dot)fnst(at)fujitsu(dot)com" <wangsh(dot)fnst(at)fujitsu(dot)com>, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>, Greg Sabino Mullane <htamfids(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: make MaxBackends available in _PG_init
Date: 2022-04-11 21:14:35
Message-ID: 20220411211435.GA2057981@nathanxps13
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On Mon, Apr 11, 2022 at 01:44:42PM -0700, Nathan Bossart wrote:
> On Mon, Apr 11, 2022 at 04:36:36PM -0400, Robert Haas wrote:
>> If we throw an error while defining_custom_guc is true, how will it
>> ever again become false?
>
> Ah, I knew I was forgetting something this morning.
>
> It won't, but the only place it is presently needed is when loading
> shared_preload_libraries, so I believe startup will fail anyway. However,
> I can see defining_custom_guc being used elsewhere, so that is probably not
> good enough. Another approach could be to add a static
> set_config_option_internal() function with a boolean argument to indicate
> whether it is being used while defining a custom GUC. I'll adjust 0003
> with that approach unless a better idea prevails.

Here's a new patch set. I've only changed 0003 as described above. My
apologies for the unnecessary round trip.

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

Attachment Content-Type Size
v2-0001-Revert-GetMaxBackends.patch text/x-diff 47.5 KB
v2-0002-Calculate-MaxBackends-earlier-in-PostmasterMain.patch text/x-diff 3.0 KB
v2-0003-Block-attempts-to-set-GUCs-while-loading-shared_p.patch text/x-diff 4.5 KB

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