Rearrange backend startup sequence so that ShmemIndexLock can become

an LWLock instead of a spinlock.  This hardly matters on Unix machines
but should improve startup performance on Windows (or any port using
EXEC_BACKEND).  Per previous discussion.

Author: tglsfdc

src/backend/bootstrap/bootstrap.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/bootstrap/bootstrap.c,v 1.209 2005/11/22 18:17:07 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/bootstrap/bootstrap.c,v 1.210 2006/01/04 21:06:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -381,22 +381,19 @@ BootstrapMain(int argc, char *argv[])
 	BaseInit();
 
 	/*
-	 * We aren't going to do the full InitPostgres pushups, but there are a
-	 * couple of things that need to get lit up even in a dummy process.
+	 * When we are a dummy process, we aren't going to do the full
+	 * InitPostgres pushups, but there are a couple of things that need
+	 * to get lit up even in a dummy process.
 	 */
 	if (IsUnderPostmaster)
 	{
-		/* set up proc.c to get use of LWLocks */
-		switch (xlogop)
-		{
-			case BS_XLOG_BGWRITER:
-				InitDummyProcess(DUMMY_PROC_BGWRITER);
-				break;
-
-			default:
-				InitDummyProcess(DUMMY_PROC_DEFAULT);
-				break;
-		}
+		/*
+		 * Create a PGPROC so we can use LWLocks.  In the EXEC_BACKEND case,
+		 * this was already done by SubPostmasterMain().
+		 */
+#ifndef EXEC_BACKEND
+		InitDummyProcess();
+#endif
 
 		/* finish setting up bufmgr.c */
 		InitBufferPoolBackend();
@@ -437,11 +434,17 @@ BootstrapMain(int argc, char *argv[])
 			proc_exit(1);
 	}
 
+	/*
+	 * We must be getting invoked for bootstrap mode
+	 */
+	Assert(!IsUnderPostmaster);
+
 	SetProcessingMode(BootstrapProcessing);
 
 	/*
-	 * backend initialization
+	 * Do backend-like initialization for bootstrap mode
 	 */
+	InitProcess();
 	(void) InitPostgres(dbname, NULL);
 
 	/*

src/backend/postmaster/autovacuum.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.8 2005/11/28 17:23:11 alvherre Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.9 2006/01/04 21:06:31 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -167,6 +167,9 @@ autovac_start(void)
 			/* Close the postmaster's sockets */
 			ClosePostmasterPorts(false);
 
+			/* Lose the postmaster's on-exit routines */
+			on_exit_reset();
+
 			AutoVacMain(0, NULL);
 			break;
 #endif
@@ -230,9 +233,6 @@ AutoVacMain(int argc, char *argv[])
 	/* reset MyProcPid */
 	MyProcPid = getpid();
 
-	/* Lose the postmaster's on-exit routines */
-	on_exit_reset();
-
 	/* Identify myself via ps */
 	init_ps_display("autovacuum process", "", "");
 	set_ps_display("");
@@ -268,6 +268,16 @@ AutoVacMain(int argc, char *argv[])
 	/* Early initialization */
 	BaseInit();
 
+	/*
+	 * Create a per-backend PGPROC struct in shared memory, except in
+	 * the EXEC_BACKEND case where this was done in SubPostmasterMain.
+	 * We must do this before we can use LWLocks (and in the EXEC_BACKEND
+	 * case we already had to do some stuff with LWLocks).
+	 */
+#ifndef EXEC_BACKEND
+	InitProcess();
+#endif
+
 	/*
 	 * If an exception is encountered, processing resumes here.
 	 *

src/backend/postmaster/pgarch.c

@@ -19,7 +19,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/pgarch.c,v 1.18 2005/10/15 02:49:23 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/pgarch.c,v 1.19 2006/01/04 21:06:31 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -158,6 +158,9 @@ pgarch_start(void)
 			/* Close the postmaster's sockets */
 			ClosePostmasterPorts(false);
 
+			/* Lose the postmaster's on-exit routines */
+			on_exit_reset();
+
 			/* Drop our connection to postmaster's shared memory, as well */
 			PGSharedMemoryDetach();
 
@@ -219,9 +222,6 @@ PgArchiverMain(int argc, char *argv[])
 
 	MyProcPid = getpid();		/* reset MyProcPid */
 
-	/* Lose the postmaster's on-exit routines */
-	on_exit_reset();
-
 	/*
 	 * Ignore all signals usually bound to some action in the postmaster,
 	 * except for SIGHUP, SIGUSR1 and SIGQUIT.

src/backend/postmaster/pgstat.c

@@ -13,7 +13,7 @@
  *
  *	Copyright (c) 2001-2005, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.118 2006/01/03 19:54:08 momjian Exp $
+ *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.119 2006/01/04 21:06:31 tgl Exp $
  * ----------
  */
 #include "postgres.h"
@@ -147,6 +147,7 @@ static int	pgStatNumBackends = 0;
 
 static volatile bool	need_statwrite;
 
+
 /* ----------
  * Local function forward declarations
  * ----------
@@ -608,6 +609,9 @@ pgstat_start(void)
 			/* Close the postmaster's sockets */
 			ClosePostmasterPorts(false);
 
+			/* Lose the postmaster's on-exit routines */
+			on_exit_reset();
+
 			/* Drop our connection to postmaster's shared memory, as well */
 			PGSharedMemoryDetach();
 
@@ -1465,9 +1469,6 @@ PgstatBufferMain(int argc, char *argv[])
 
 	MyProcPid = getpid();		/* reset MyProcPid */
 
-	/* Lose the postmaster's on-exit routines */
-	on_exit_reset();
-
 	/*
 	 * Ignore all signals usually bound to some action in the postmaster,
 	 * except for SIGCHLD and SIGQUIT --- see pgstat_recvbuffer.
@@ -1551,10 +1552,10 @@ PgstatCollectorMain(int argc, char *argv[])
 	fd_set		rfds;
 	int			readPipe;
 	int			len = 0;
-	struct itimerval timeval;
+	struct itimerval timeout;
 	HASHCTL		hash_ctl;
 	bool		need_timer = false;
-	
+
 	MyProcPid = getpid();		/* reset MyProcPid */
 
 	/*
@@ -1597,11 +1598,15 @@ PgstatCollectorMain(int argc, char *argv[])
 	init_ps_display("stats collector process", "", "");
 	set_ps_display("");
 
+	/*
+	 * Arrange to write the initial status file right away
+	 */
 	need_statwrite = true;
 
-	MemSet(&timeval, 0, sizeof(struct itimerval));
-	timeval.it_value.tv_sec = PGSTAT_STAT_INTERVAL / 1000;
-	timeval.it_value.tv_usec = PGSTAT_STAT_INTERVAL % 1000;
+	/* Preset the delay between status file writes */
+	MemSet(&timeout, 0, sizeof(struct itimerval));
+	timeout.it_value.tv_sec = PGSTAT_STAT_INTERVAL / 1000;
+	timeout.it_value.tv_usec = PGSTAT_STAT_INTERVAL % 1000;
 
 	/*
 	 * Read in an existing statistics stats file or initialize the stats to
@@ -1634,6 +1639,12 @@ PgstatCollectorMain(int argc, char *argv[])
 	 */
 	for (;;)
 	{
+		/*
+		 * If time to write the stats file, do so.  Note that the alarm
+		 * interrupt isn't re-enabled immediately, but only after we next
+		 * receive a stats message; so no cycles are wasted when there is
+		 * nothing going on.
+		 */
 		if (need_statwrite)
 		{
 			pgstat_write_statsfile();
@@ -1776,11 +1787,16 @@ PgstatCollectorMain(int argc, char *argv[])
 			 */
 			pgStatNumMessages++;
 
+			/*
+			 * If this is the first message after we wrote the stats file the
+			 * last time, enable the alarm interrupt to make it be written
+			 * again later.
+			 */
 			if (need_timer)
 			{
-				if (setitimer(ITIMER_REAL, &timeval, NULL))
+				if (setitimer(ITIMER_REAL, &timeout, NULL))
 					ereport(ERROR,
-						  (errmsg("unable to set statistics collector timer: %m")));
+						  (errmsg("could not set statistics collector timer: %m")));
 				need_timer = false;
 			}
 		}
@@ -1806,6 +1822,7 @@ PgstatCollectorMain(int argc, char *argv[])
 }
 
 
+/* SIGALRM signal handler for collector process */
 static void
 force_statwrite(SIGNAL_ARGS)
 {
@@ -1913,8 +1930,10 @@ pgstat_recvbuffer(void)
 		/*
 		 * Wait for some work to do; but not for more than 10 seconds. (This
 		 * determines how quickly we will shut down after an ungraceful
-		 * postmaster termination; so it needn't be very fast.)  struct timeout
-		 * is modified by some operating systems.
+		 * postmaster termination; so it needn't be very fast.)
+		 *
+		 * struct timeout is modified by select() on some operating systems,
+		 * so re-fill it each time.
 		 */
 		timeout.tv_sec = 10;
 		timeout.tv_usec = 0;