From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Thu, 9 Jul 2026 12:14:19 +0000 (+0300)
Subject: Fix advertising autovacuum launcher's ProcNumber
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=dff789e555404571cc76097c1539e93dc7f2e3de;p=thirdparty%2Fpostgresql.git

Fix advertising autovacuum launcher's ProcNumber

Autovacuum launcher is not an aux process, so it needs to be
advertised in InitProcess() rather than InitAuxiliaryProcess()

In the passing, also remove some now-unnecessary 'volatile' qualifiers
left behind by the same commit.

Reported-by: Thom Brown <thom@linux.com>
Author: Fujii Masao <masao.fujii@gmail.com>
Author: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAA-aLv6UHXubNxmAjNH8PnyKKkaXePO1ggB15=iidNW08T4hSg@mail.gmail.com
---

diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index a09d4097d51..f6351f1eb10 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -1114,8 +1114,7 @@ RequestCheckpoint(int flags)
 #define MAX_SIGNAL_TRIES 600	/* max wait 60.0 sec */
 	for (ntries = 0;; ntries++)
 	{
-		volatile PROC_HDR *procglobal = ProcGlobal;
-		ProcNumber	checkpointerProc = pg_atomic_read_u32(&procglobal->checkpointerProc);
+		ProcNumber	checkpointerProc = pg_atomic_read_u32(&ProcGlobal->checkpointerProc);
 
 		if (checkpointerProc == INVALID_PROC_NUMBER)
 		{
@@ -1536,8 +1535,7 @@ FirstCallSinceLastCheckpoint(void)
 void
 WakeupCheckpointer(void)
 {
-	volatile PROC_HDR *procglobal = ProcGlobal;
-	ProcNumber	checkpointerProc = pg_atomic_read_u32(&procglobal->checkpointerProc);
+	ProcNumber	checkpointerProc = pg_atomic_read_u32(&ProcGlobal->checkpointerProc);
 
 	if (checkpointerProc != INVALID_PROC_NUMBER)
 		SetLatch(&GetPGProcByNumber(checkpointerProc)->procLatch);
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 59640bb4f97..9d6e69175a5 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -550,6 +550,10 @@ InitProcess(void)
 	 */
 	PGSemaphoreReset(MyProc->sem);
 
+	/* autovacuum launcher is specially advertised in ProcGlobal */
+	if (MyBackendType == B_AUTOVAC_LAUNCHER)
+		pg_atomic_write_u32(&ProcGlobal->avLauncherProc, MyProcNumber);
+
 	/*
 	 * Arrange to clean up at backend exit.
 	 */
@@ -726,8 +730,6 @@ 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 +991,12 @@ 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 +1121,6 @@ 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);
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 0314f979e60..03a1a466fa8 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -491,9 +491,10 @@ typedef struct PROC_HDR
 	 * Current proc numbers of some auxiliary processes. There can be only one
 	 * of each of these running at a time.
 	 */
-	pg_atomic_uint32 avLauncherProc;
 	pg_atomic_uint32 walwriterProc;
 	pg_atomic_uint32 checkpointerProc;
+	/* avlauncher is not an aux process, but it is advertised the same way */
+	pg_atomic_uint32 avLauncherProc;
 
 	/* Current shared estimate of appropriate spins_per_delay value */
 	int			spins_per_delay;