Separate the code to start a new worker into its own function. The code is

exactly the same, modulo whitespace.

src/backend/postmaster/autovacuum.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.36 2007/03/23 21:23:13 alvherre Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.37 2007/03/23 21:45:17 alvherre Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -118,6 +118,7 @@ static pid_t avworker_forkexec(void);
 NON_EXEC_STATIC void AutoVacWorkerMain(int argc, char *argv[]);
 NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]);
 
+static void do_start_worker(void);
 static void do_autovacuum(PgStat_StatDBEntry *dbentry);
 static List *autovac_get_database_list(void);
 static void test_rel_for_autovac(Oid relid, PgStat_StatTabEntry *tabentry,
@@ -218,9 +219,6 @@ NON_EXEC_STATIC void
 AutoVacLauncherMain(int argc, char *argv[])
 {
 	sigjmp_buf	local_sigjmp_buf;
-	List	   *dblist;
-	bool		for_xid_wrap;
-	autovac_dbase *db;
 	MemoryContext	avlauncher_cxt;
 
 	/* we are a postmaster subprocess now */
@@ -358,8 +356,6 @@ AutoVacLauncherMain(int argc, char *argv[])
 
 	for (;;)
 	{
-		TransactionId xidForceLimit;
-		ListCell *cell;
 		int		worker_pid;
 
 		/*
@@ -407,6 +403,49 @@ AutoVacLauncherMain(int argc, char *argv[])
 			}
 		}
 
+		do_start_worker();
+
+sleep:
+		/*
+		 * in emergency mode, exit immediately so that the postmaster can
+		 * request another run right away if needed.
+		 *
+		 * XXX -- maybe it would be better to handle this inside the launcher
+		 * itself.
+		 */
+		if (!autovacuum_start_daemon)
+			break;
+
+		/* have pgstat read the file again next time */
+		pgstat_clear_snapshot();
+
+		/* now sleep until the next autovac iteration */
+		pg_usleep(autovacuum_naptime * 1000000L); 
+	}
+
+	/* Normal exit from the autovac launcher is here */
+	ereport(LOG,
+			(errmsg("autovacuum launcher shutting down")));
+
+	proc_exit(0);		/* done */
+}
+
+/*
+ * do_start_worker
+ *
+ * Bare-bones procedure for starting an autovacuum worker from the launcher.
+ * It determines what database to work on, sets up shared memory stuff and
+ * signals postmaster to start the worker.
+ */
+static void
+do_start_worker(void)
+{
+	List	   *dblist;
+	bool		for_xid_wrap;
+	autovac_dbase *db;
+	ListCell *cell;
+	TransactionId xidForceLimit;
+
 	/* Get a list of databases */
 	dblist = autovac_get_database_list();
 
@@ -486,30 +525,6 @@ AutoVacLauncherMain(int argc, char *argv[])
 
 		SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
 	}
-		
-sleep:
-		/*
-		 * in emergency mode, exit immediately so that the postmaster can
-		 * request another run right away if needed.
-		 *
-		 * XXX -- maybe it would be better to handle this inside the launcher
-		 * itself.
-		 */
-		if (!autovacuum_start_daemon)
-			break;
-
-		/* have pgstat read the file again next time */
-		pgstat_clear_snapshot();
-
-		/* now sleep until the next autovac iteration */
-		pg_usleep(autovacuum_naptime * 1000000L); 
-	}
-
-	/* Normal exit from the autovac launcher is here */
-	ereport(LOG,
-			(errmsg("autovacuum launcher shutting down")));
-
-	proc_exit(0);		/* done */
 }
 
 /* SIGHUP: set flag to re-read config file at next convenient time */