From: Tom Lane <tgl@sss.pgh.pa.us>
To: pgsql-hackers@lists.postgresql.org
Subject: Re: Subscription tests fail under CLOBBER_CACHE_ALWAYS
In-reply-to: <165922.1621635259@sss.pgh.pa.us>
References: <3382681.1621381328@sss.pgh.pa.us>
 <165922.1621635259@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Fri, 21 May 2021 18:14:19 -0400"
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Date: Fri, 21 May 2021 19:54:48 -0400
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I wrote:
> BTW, I wonder whether it wouldn't be a good idea for the
> postmaster to log something along the lines of "stopping
> because restart_after_crash is off".  The present behavior
> can be quite mysterious otherwise (it certainly confused me).

Concretely, I suggest the attached.

While checking the other ExitPostmaster calls to see if any of
them lacked suitable log messages, I noticed that there's one
after a call to AuxiliaryProcessMain, which is marked
pg_attribute_noreturn().  So that's dead code, and if it
weren't dead it'd be wrong, because we shouldn't use
ExitPostmaster to exit a child process.

			regards, tom lane


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	name="log-explanation-when-postmaster-shuts-down.patch";
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diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/=
postmaster.c
index 5327859472..5a050898fe 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -3973,7 +3973,11 @@ PostmasterStateMachine(void)
 			if (ReachedNormalRunning)
 				CancelBackup();
 =

-			/* Normal exit from the postmaster is here */
+			/*
+			 * Normal exit from the postmaster is here.  We don't need to log
+			 * anything here, since the UnlinkLockFiles proc_exit callback
+			 * will do so, and that should be the last user-visible action.
+			 */
 			ExitPostmaster(0);
 		}
 	}
@@ -3985,9 +3989,21 @@ PostmasterStateMachine(void)
 	 * startup process fails, because more than likely it will just fail aga=
in
 	 * and we will keep trying forever.
 	 */
-	if (pmState =3D=3D PM_NO_CHILDREN &&
-		(StartupStatus =3D=3D STARTUP_CRASHED || !restart_after_crash))
-		ExitPostmaster(1);
+	if (pmState =3D=3D PM_NO_CHILDREN)
+	{
+		if (StartupStatus =3D=3D STARTUP_CRASHED)
+		{
+			ereport(LOG,
+					(errmsg("shutting down due to startup process failure")));
+			ExitPostmaster(1);
+		}
+		if (!restart_after_crash)
+		{
+			ereport(LOG,
+					(errmsg("shutting down because restart_after_crash is off")));
+			ExitPostmaster(1);
+		}
+	}
 =

 	/*
 	 * If we need to recover from a crash, wait for all non-syslogger childr=
en
@@ -5439,8 +5455,7 @@ StartChildProcess(AuxProcType type)
 		MemoryContextDelete(PostmasterContext);
 		PostmasterContext =3D NULL;
 =

-		AuxiliaryProcessMain(ac, av);
-		ExitPostmaster(0);
+		AuxiliaryProcessMain(ac, av);	/* does not return */
 	}
 #endif							/* EXEC_BACKEND */
 =


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