Rearrange handling of MAXBACKENDS a little bit. The default setting

of MAXBACKENDS is now 1024, since all it's costing is about 32 bytes of memory
per array slot.  configure's --with-maxbackends switch now controls DEF_MAXBACKENDS
which is simply the default value of the postmaster's -N switch.  Thus,
the out-of-the-box configuration will still limit you to 64 backends,
but you can go up to 1024 backends simply by restarting the postmaster with
a different -N switch --- no rebuild required.

3 files changed, 15 insertions, 9 deletions

diff --git a/src/include/config.h.in b/src/include/config.h.in
index ad277bd001..07e48851ff 100644
--- a/src/include/config.h.in
+++ b/src/include/config.h.in
@@ -9,10 +9,17 @@
 #define CONFIG_H
 
 /*
- * Maximum number of backend server processes per postmaster.
+ * Default runtime limit on number of backend server processes per postmaster;
+ * this is just the default setting for the postmaster's -N switch.
  * (Actual value is set by configure script.)
  */
-#undef MAXBACKENDS
+#undef DEF_MAXBACKENDS
+
+/*
+ * Hard limit on number of backend server processes per postmaster.
+ * Increasing this costs about 32 bytes per process slot as of v 6.5.
+ */
+#define MAXBACKENDS	(DEF_MAXBACKENDS > 1024 ? DEF_MAXBACKENDS : 1024)
 
 /*
  * Size of a disk block --- currently, this limits the size of a tuple.
diff --git a/src/include/storage/ipc.h b/src/include/storage/ipc.h
index 76a11e5b13..e9a96c8190 100644
--- a/src/include/storage/ipc.h
+++ b/src/include/storage/ipc.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: ipc.h,v 1.33 1999/02/19 06:06:33 tgl Exp $
+ * $Id: ipc.h,v 1.34 1999/02/21 01:41:47 tgl Exp $
  *
  * NOTES
  *	  This file is very architecture-specific.	This stuff should actually
@@ -96,7 +96,6 @@ extern void AttachSLockMemory(IPCKey key);
 
 #ifdef HAS_TEST_AND_SET
 
-#define NSLOCKS			2048
 #define NOLOCK			0
 #define SHAREDLOCK		1
 #define EXCLUSIVELOCK	2
diff --git a/src/include/storage/lock.h b/src/include/storage/lock.h
index 85af296a5b..ce1f30133f 100644
--- a/src/include/storage/lock.h
+++ b/src/include/storage/lock.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: lock.h,v 1.22 1999/02/19 06:06:35 tgl Exp $
+ * $Id: lock.h,v 1.23 1999/02/21 01:41:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -28,14 +28,14 @@ typedef int MASK;
 /* ----------------------
  * The following defines are used to estimate how much shared
  * memory the lock manager is going to require.
+ * See LockShmemSize() in lock.c.
  *
- * MAXBACKENDS - The max number of concurrently running backends (config.h)
  * NLOCKS_PER_XACT - The number of unique locks acquired in a transaction
  * NLOCKENTS - The maximum number of lock entries in the lock table.
  * ----------------------
  */
-#define NLOCKS_PER_XACT	40
-#define NLOCKENTS		(NLOCKS_PER_XACT*MAXBACKENDS)
+#define NLOCKS_PER_XACT			40
+#define NLOCKENTS(maxBackends)	(NLOCKS_PER_XACT*(maxBackends))
 
 typedef int LOCKMODE;
 typedef int LOCKMETHOD;
@@ -242,7 +242,7 @@ extern bool LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
 			LOCKMODE lockmode);
 extern void GrantLock(LOCK *lock, LOCKMODE lockmode);
 extern bool LockReleaseAll(LOCKMETHOD lockmethod, SHM_QUEUE *lockQueue);
-extern int	LockShmemSize(void);
+extern int	LockShmemSize(int maxBackends);
 extern bool LockingDisabled(void);
 extern bool DeadLockCheck(SHM_QUEUE *lockQueue, LOCK *findlock,
 			  bool skip_check);