Date: Thu, 2 Jul 2020 11:11:17 -0400
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Mike Palmiotto <mike.palmiotto@crunchydata.com>
Cc: Andres Freund <andres@anarazel.de>,
	Peter Eisentraut <peter.eisentraut@2ndquadrant.com>,
	Justin Pryzby <pryzby@telsasoft.com>,
	Michael Paquier <michael@paquier.xyz>,
	Yuli Khodorkovskiy <yuli.khodorkovskiy@crunchydata.com>,
	Tom Lane <tgl@sss.pgh.pa.us>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Auxiliary Processes and MyAuxProc
Message-ID: <20200702151117.GA4919@alvherre.pgsql>
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On 2020-Mar-26, Mike Palmiotto wrote:

Regarding 0001:

> diff --git a/src/backend/postmaster/subprocess.c b/src/backend/postmaster/subprocess.c
> new file mode 100644
> index 0000000000..3e7a45bf10
> --- /dev/null
> +++ b/src/backend/postmaster/subprocess.c
> @@ -0,0 +1,62 @@
> +/*-------------------------------------------------------------------------
> + *
> + * subprocess.c
> + *
> + * Copyright (c) 2004-2020, PostgreSQL Global Development Group
> + *
> + *
> + * IDENTIFICATION
> + *	  src/backend/postmaster/syslogger.c

Wrong file identification.

> +static PgSubprocess process_types[] = {
> +	{
> +		.desc = "checker",
> +		.entrypoint = CheckerModeMain
> +	},
> +	{
...

This array has to match the order in subprocess.h:

> +typedef enum
> +{
> +	NoProcessType = -1,
> +	CheckerType = 0,
> +	BootstrapType,
> +	StartupType,
> +	BgWriterType,
> +	CheckpointerType,
> +	WalWriterType,
> +	WalReceiverType,	/* end of Auxiliary Process Forks */
> +
> +	NUMSUBPROCESSTYPES			/* Must be last! */
> +} SubprocessType;

This sort of thing is messy and unfriendly to maintain.  I suggest we
use the same trick as in cmdtaglist.h and rmgrlist.h; see commits
2f9661311b83 and 5a1cd89f8f4a for examples.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services