public inbox for [email protected]  

help / color / mirror / Atom feed

From: David Rowley <[email protected]>
To: Andres Freund <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: [email protected]
Cc: Robert Haas <[email protected]>
Subject: Re: catalog access with reset GUCs during parallel worker startup
Date: Thu, 7 Dec 2023 19:33:13 +1300
Message-ID: <CAApHDvrcWM9ize8oLujumwaEmTTcmQWXtHe4C-TiD1Dx2jAtFA@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
	<[email protected]>
	<[email protected]>

On Thu, 10 Feb 2022 at 13:33, Andres Freund <[email protected]> wrote:
> Postmaster's GUC state will already be loaded via read_nondefault_variables(),
> much earlier in startup. Well before bgworkers get control and before
> transaction environment is up.
>
> Setting a watchpoint on enableFsync, in a parallel worker where postmaster
> runs with enableFsync=off, shows the following:

The following comment in RestoreGUCState() starting with "since the
leader's" seems to indicate this step is required.

> * but already have their default values.  Thus, this ends up being the
> * same test that SerializeGUCState uses, even though the sets of
> * variables involved may well be different since the leader's set of
> * variables-not-at-default-values can differ from the set that are
>  * not-default in this freshly started worker.

I'm just not quite clear on which cases this could be.   Looking at
InitializeOneGUCOption(), the newval comes from conf->boot_val, which,
for built-in GUCs just comes from the ConfigureNames* table in
guc_tables.c. Perhaps there could be variances in values that are
passed during the call to DefineCustom*Variable between the leader and
the worker in some extension's code.

David

view thread (6+ messages)

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected], [email protected], [email protected], [email protected]
  Subject: Re: catalog access with reset GUCs during parallel worker startup
  In-Reply-To: <CAApHDvrcWM9ize8oLujumwaEmTTcmQWXtHe4C-TiD1Dx2jAtFA@mail.gmail.com>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox