public inbox for [email protected]  

help / color / mirror / Atom feed

From: Fujii Masao <[email protected]>
To: Thom Brown <[email protected]>
Cc: Heikki Linnakangas <[email protected]>
Cc: [email protected]
Subject: Re: pgsql: Refactor how some aux processes advertise their ProcNumber
Date: Thu, 9 Jul 2026 09:57:27 +0900
Message-ID: <CAHGQGwH8n4BMjBJcL1ob6YTJYn1kTmVwO6mEYoEGyrGyNXaaXw@mail.gmail.com> (raw)
In-Reply-To: <CAA-aLv6UHXubNxmAjNH8PnyKKkaXePO1ggB15=iidNW08T4hSg@mail.gmail.com>
References: <[email protected]>
	<CAA-aLv6UHXubNxmAjNH8PnyKKkaXePO1ggB15=iidNW08T4hSg@mail.gmail.com>

On Thu, Jul 9, 2026 at 6:57 AM Thom Brown <[email protected]> wrote:
> @@ -724,6 +725,14 @@ InitAuxiliaryProcess(void)
>      */
>     PGSemaphoreReset(MyProc->sem);
>
> +   /* Some aux processes are also advertised in ProcGlobal */
> +   if (MyBackendType == B_AUTOVAC_LAUNCHER)
> +       pg_atomic_write_u32(&ProcGlobal->avLauncherProc, MyProcNumber);
>
> I'm looking for the places this gets called from. I can only see
> auxprocess.c which the launcher doesn't go through. The same question
> for similar code in AuxiliaryProcKill().

You're right. The autovacuum launcher does not go through
AuxiliaryProcessMainCommon(), so it never calls
InitAuxiliaryProcess(). Instead, it initializes its PGPROC with
InitProcess().

As a result, the avLauncherProc assignment added to
InitAuxiliaryProcess() is never executed for the launcher, and the
corresponding cleanup in AuxiliaryProcKill() is never reached either.

It seems we should move the avLauncherProc set/clear operations to
InitProcess()/ProcKill() path, as in the attached patch.

Regards,

-- 
Fujii Masao


Attachments:

  [application/octet-stream] v1-0001-Advertise-autovacuum-launcher-s-ProcNumber-from-I.patch (2.0K, ../CAHGQGwH8n4BMjBJcL1ob6YTJYn1kTmVwO6mEYoEGyrGyNXaaXw@mail.gmail.com/2-v1-0001-Advertise-autovacuum-launcher-s-ProcNumber-from-I.patch)
  download | inline diff:
From 86d84b81e53497cdda9722cb223df53970491714 Mon Sep 17 00:00:00 2001
From: Fujii Masao <[email protected]>
Date: Thu, 9 Jul 2026 09:23:46 +0900
Subject: [PATCH v1] Advertise autovacuum launcher's ProcNumber from
 InitProcess

---
 src/backend/storage/lmgr/proc.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 59640bb4f97..ce4425b5568 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -550,6 +550,9 @@ InitProcess(void)
 	 */
 	PGSemaphoreReset(MyProc->sem);
 
+	if (MyBackendType == B_AUTOVAC_LAUNCHER)
+		pg_atomic_write_u32(&ProcGlobal->avLauncherProc, MyProcNumber);
+
 	/*
 	 * Arrange to clean up at backend exit.
 	 */
@@ -726,8 +729,6 @@ InitAuxiliaryProcess(void)
 	PGSemaphoreReset(MyProc->sem);
 
 	/* Some aux processes are also advertised in ProcGlobal */
-	if (MyBackendType == B_AUTOVAC_LAUNCHER)
-		pg_atomic_write_u32(&ProcGlobal->avLauncherProc, MyProcNumber);
 	if (MyBackendType == B_WAL_WRITER)
 		pg_atomic_write_u32(&ProcGlobal->walwriterProc, MyProcNumber);
 	if (MyBackendType == B_CHECKPOINTER)
@@ -989,6 +990,12 @@ ProcKill(int code, Datum arg)
 	SwitchBackToLocalLatch();
 	DisownLatch(&MyProc->procLatch);
 
+	if (MyBackendType == B_AUTOVAC_LAUNCHER)
+	{
+		Assert(pg_atomic_read_u32(&ProcGlobal->avLauncherProc) == MyProcNumber);
+		pg_atomic_write_u32(&ProcGlobal->avLauncherProc, INVALID_PROC_NUMBER);
+	}
+
 	proc = MyProc;
 	procgloballist = proc->procgloballist;
 
@@ -1113,11 +1120,6 @@ AuxiliaryProcKill(int code, Datum arg)
 	/*
 	 * If this was one of the aux processes advertised in ProcGlobal, clear it
 	 */
-	if (MyBackendType == B_AUTOVAC_LAUNCHER)
-	{
-		Assert(pg_atomic_read_u32(&ProcGlobal->avLauncherProc) == MyProcNumber);
-		pg_atomic_write_u32(&ProcGlobal->avLauncherProc, INVALID_PROC_NUMBER);
-	}
 	if (MyBackendType == B_WAL_WRITER)
 	{
 		Assert(pg_atomic_read_u32(&ProcGlobal->walwriterProc) == MyProcNumber);
-- 
2.55.0

view thread (8+ messages)  latest in thread

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: pgsql: Refactor how some aux processes advertise their ProcNumber
  In-Reply-To: <CAHGQGwH8n4BMjBJcL1ob6YTJYn1kTmVwO6mEYoEGyrGyNXaaXw@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