Under new theory of operation wherein postmaster forks children

immediately, we will fork a child even if the database state does not
permit connections to be accepted (eg, we are in recovery mode).
The child process will correctly reject the connection and exit as
soon as it's finished collecting the connection request message.
However, this means that reaper() must be prepared to see child
process exit signals even while it's waiting for startup or shutdown
process to finish.  As was, a connection request arriving during a
database recovery or shutdown would cause postmaster abort.

src/backend/postmaster/postmaster.c

@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.229 2001/06/29 16:05:57 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.230 2001/07/01 00:06:23 tgl Exp $
  *
  * NOTES
  *
@@ -1357,7 +1357,11 @@ pmdie(SIGNAL_ARGS)
 				return;
 			}
 			if (ShutdownPID > 0)
+			{
+				postmaster_error("Shutdown process %d already running",
+								 ShutdownPID);
 				abort();
+			}
 
 			ShutdownPID = ShutdownDataBase();
 			errno = save_errno;
@@ -1409,7 +1413,11 @@ pmdie(SIGNAL_ARGS)
 				return;
 			}
 			if (ShutdownPID > 0)
+			{
+				postmaster_error("Shutdown process %d already running",
+								 ShutdownPID);
 				abort();
+			}
 
 			ShutdownPID = ShutdownDataBase();
 			errno = save_errno;
@@ -1481,27 +1489,21 @@ reaper(SIGNAL_ARGS)
 			continue;
 		}
 
-		if (ShutdownPID > 0)
+		if (ShutdownPID > 0 && pid == ShutdownPID)
 		{
-			if (pid != ShutdownPID)
-				abort();
 			if (exitstatus != 0)
 			{
 				postmaster_error("Shutdown proc %d exited with status %d", pid, exitstatus);
-				fflush(stderr);
 				ExitPostmaster(1);
 			}
 			ExitPostmaster(0);
 		}
-		if (StartupPID > 0)
+		if (StartupPID > 0 && pid == StartupPID)
 		{
-			if (pid != StartupPID)
-				abort();
 			if (exitstatus != 0)
 			{
 				postmaster_error("Startup proc %d exited with status %d - abort",
 								 pid, exitstatus);
-				fflush(stderr);
 				ExitPostmaster(1);
 			}
 			StartupPID = 0;
@@ -1509,7 +1511,11 @@ reaper(SIGNAL_ARGS)
 			if (Shutdown > NoShutdown)
 			{
 				if (ShutdownPID > 0)
+				{
+					postmaster_error("Shutdown process %d already running",
+									 ShutdownPID);
 					abort();
+				}
 				ShutdownPID = ShutdownDataBase();
 			}
 
@@ -1533,7 +1539,6 @@ reaper(SIGNAL_ARGS)
 
 	if (FatalError)
 	{
-
 		/*
 		 * Wait for all children exit, then reset shmem and
 		 * StartupDataBase.