[Tom Lane <tgl@sss.pgh.pa.us>]

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

Attachments:

log-explanation-when-postmaster-shuts-down.patch (text/x-diff, 1.6K) download
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 again
 	 * and we will keep trying forever.
 	 */
-	if (pmState == PM_NO_CHILDREN &&
-		(StartupStatus == STARTUP_CRASHED || !restart_after_crash))
-		ExitPostmaster(1);
+	if (pmState == PM_NO_CHILDREN)
+	{
+		if (StartupStatus == 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 children
@@ -5439,8 +5455,7 @@ StartChildProcess(AuxProcType type)
 		MemoryContextDelete(PostmasterContext);
 		PostmasterContext = NULL;
 
-		AuxiliaryProcessMain(ac, av);
-		ExitPostmaster(0);
+		AuxiliaryProcessMain(ac, av);	/* does not return */
 	}
 #endif							/* EXEC_BACKEND */
 =