Get rid of PID entries in shmem hash table; there is no longer any need

for them, and making them just wastes time during backend startup/shutdown.
Also, remove compile-time MAXBACKENDS limit per long-ago proposal.
You can now set MaxBackends as high as your kernel can stand without
any reconfiguration/recompilation.

contrib/userlock/user_locks.c

@@ -73,20 +73,10 @@ user_write_unlock_oid(Oid oid)
 }
 
 int
-user_unlock_all()
+user_unlock_all(void)
 {
-	PROC	   *proc;
-	SHMEM_OFFSET location;
-
-	ShmemPIDLookup(MyProcPid, &location);
-	if (location == INVALID_OFFSET)
-	{
-		elog(NOTICE, "UserUnlockAll: unable to get proc ptr");
-		return -1;
-	}
-
-	proc = (PROC *) MAKE_PTR(location);
-	return LockReleaseAll(USER_LOCKMETHOD, proc, false, InvalidTransactionId);
+	return LockReleaseAll(USER_LOCKMETHOD, MyProc, false,
+						  InvalidTransactionId);
 }
 
 /* end of file */

src/backend/port/darwin/sem.c

@@ -10,10 +10,11 @@
  *	 - this required changing sem_info from containig an array of sem_t to an array of sem_t*
  *
  * IDENTIFICATION
- *		 $Header: /cvsroot/pgsql/src/backend/port/darwin/Attic/sem.c,v 1.3 2001/03/22 03:59:42 momjian Exp $
+ *		 $Header: /cvsroot/pgsql/src/backend/port/darwin/Attic/sem.c,v 1.4 2001/09/07 00:27:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
+#include "postgres.h"
 
 #include <errno.h>
 #include <semaphore.h>
@@ -22,13 +23,13 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <sys/mman.h>
-#include "postgres.h"
+
+#include "miscadmin.h"
 #include "storage/ipc.h"
 #include "storage/proc.h"
 #include "port/darwin/sem.h"
 
 #define SEMMAX	IPC_NMAXSEM
-#define SETMAX ((MAXBACKENDS + SEMMAX - 1) / SEMMAX)
 #define OPMAX	8
 
 #define MODE	0700
@@ -41,19 +42,23 @@ struct pending_ops
 	int			idx;			/* index of first free array member */
 };
 
-struct sem_info
+struct sem_set_info
 {
-	sem_t	   *sem;
-	struct
-	{
 	key_t		key;
 	int			nsems;
-		sem_t	   *sem[SEMMAX];/* array of POSIX semaphores */
+	sem_t	   *sem[SEMMAX];	/* array of POSIX semaphores */
 	struct sem	semV[SEMMAX];	/* array of System V semaphore
 								 * structures */
 	struct pending_ops pendingOps[SEMMAX];	/* array of pending
 											 * operations */
-	}			set[SETMAX];
+};
+
+struct sem_info
+{
+	sem_t	   *sem;
+	int			nsets;
+	/* there are actually nsets of these: */
+	struct sem_set_info set[1];	/* VARIABLE LENGTH ARRAY */
 };
 
 static struct sem_info *SemInfo = (struct sem_info *) - 1;
@@ -66,7 +71,7 @@ semctl(int semid, int semnum, int cmd, /* ... */ union semun arg)
 
 	sem_wait(SemInfo->sem);
 
-	if (semid < 0 || semid >= SETMAX ||
+	if (semid < 0 || semid >= SemInfo->nsets ||
 		semnum < 0 || semnum >= SemInfo->set[semid].nsems)
 	{
 		sem_post(SemInfo->sem);
@@ -132,8 +137,10 @@ semget(key_t key, int nsems, int semflg)
 {
 	int			fd,
 				semid,
-				semnum /* , semnum1 */ ;
+				semnum,
+				nsets;
 	int			exist = 0;
+	Size		sem_info_size;
 	char		semname[64];
 
 	if (nsems < 0 || nsems > SEMMAX)
@@ -163,13 +170,20 @@ semget(key_t key, int nsems, int semflg)
 			return fd;
 		shm_unlink(SHM_INFO_NAME);
 		/* The size may only be set once. Ignore errors. */
-		ftruncate(fd, sizeof(struct sem_info));
-		SemInfo = mmap(NULL, sizeof(struct sem_info),
+		nsets = PROC_SEM_MAP_ENTRIES(MaxBackends);
+		sem_info_size = sizeof(struct sem_info) + (nsets-1) * sizeof(struct sem_set_info);
+		ftruncate(fd, sem_info_size);
+		SemInfo = mmap(NULL, sem_info_size,
 					   PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 		if (SemInfo == MAP_FAILED)
 			return -1;
 		if (!exist)
 		{
+			/* initialize shared memory */
+			memset(SemInfo, 0, sem_info_size);
+			SemInfo->nsets = nsets;
+			for (semid = 0; semid < nsets; semid++)
+				SemInfo->set[semid].key = -1;
 			/* create semaphore for locking */
 			sprintf(semname, "%s-map", SEM_NAME);
 #ifdef DEBUG_IPC
@@ -177,30 +191,25 @@ semget(key_t key, int nsems, int semflg)
 #endif
 			SemInfo->sem = sem_open(semname, O_CREAT, semflg & 0777, 1);
 			sem_unlink(semname);
-			sem_wait(SemInfo->sem);
-			/* initilize shared memory */
-			memset(SemInfo->set, 0, sizeof(SemInfo->set));
-			for (semid = 0; semid < SETMAX; semid++)
-				SemInfo->set[semid].key = -1;
-			sem_post(SemInfo->sem);
 		}
 	}
 
 	sem_wait(SemInfo->sem);
+	nsets = SemInfo->nsets;
 
 	if (key != IPC_PRIVATE)
 	{
 		/* search existing element */
 		semid = 0;
-		while (semid < SETMAX && SemInfo->set[semid].key != key)
+		while (semid < nsets && SemInfo->set[semid].key != key)
 			semid++;
-		if (!(semflg & IPC_CREAT) && semid >= SETMAX)
+		if (!(semflg & IPC_CREAT) && semid >= nsets)
 		{
 			sem_post(SemInfo->sem);
 			errno = ENOENT;
 			return -1;
 		}
-		else if (semid < SETMAX)
+		else if (semid < nsets)
 		{
 			if (semflg & IPC_CREAT && semflg & IPC_EXCL)
 			{
@@ -228,12 +237,12 @@ semget(key_t key, int nsems, int semflg)
 
 	/* search first free element */
 	semid = 0;
-	while (semid < SETMAX && SemInfo->set[semid].key != -1)
+	while (semid < nsets && SemInfo->set[semid].key != -1)
 		semid++;
-	if (semid >= SETMAX)
+	if (semid >= nsets)
 	{
 #ifdef DEBUG_IPC
-		fprintf(stderr, "darwin semget failed because all keys were -1 up to SETMAX\n");
+		fprintf(stderr, "darwin semget failed because all keys were -1\n");
 #endif
 		sem_post(SemInfo->sem);
 		errno = ENOSPC;
@@ -249,15 +258,18 @@ semget(key_t key, int nsems, int semflg)
 		SemInfo->set[semid].sem[semnum] = sem_open(semname, O_CREAT, semflg & 0777, 0);
 		sem_unlink(semname);
 
-/* Currently sem_init always returns -1.
+		/* Currently sem_init always returns -1. */
+#ifdef NOT_USED
 		if( sem_init( &SemInfo->set[semid].sem[semnum], 1, 0 ) == -1 )	{
+			int semnum1;
+
 			for( semnum1 = 0; semnum1 < semnum; semnum1++ )  {
 				sem_close( SemInfo->set[semid].sem[semnum1] );
 			}
 			sem_post( SemInfo->sem );
 			return -1;
 		}
-*/
+#endif
 	}
 
 	SemInfo->set[semid].key = key;
@@ -279,7 +291,7 @@ semop(int semid, struct sembuf * sops, size_t nsops)
 
 	sem_wait(SemInfo->sem);
 
-	if (semid < 0 || semid >= SETMAX)
+	if (semid < 0 || semid >= SemInfo->nsets)
 	{
 		sem_post(SemInfo->sem);
 		errno = EINVAL;

src/backend/port/qnx4/sem.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/port/qnx4/Attic/sem.c,v 1.6 2001/08/24 14:07:49 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/port/qnx4/Attic/sem.c,v 1.7 2001/09/07 00:27:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -21,14 +21,15 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <sys/mman.h>
-#include "storage/ipc.h"
-#include "storage/proc.h"
 #include <sys/sem.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
 
+#include "miscadmin.h"
+#include "storage/ipc.h"
+#include "storage/proc.h"
+
 
-#define SETMAX	((MAXBACKENDS + PROC_NSEMS_PER_SET + 1) / PROC_NSEMS_PER_SET)
 #define SEMMAX	(PROC_NSEMS_PER_SET+1)
 #define OPMAX	8
 
@@ -42,19 +43,23 @@ struct pending_ops
 	int			idx;			/* index of first free array member */
 };
 
-struct sem_info
+struct sem_set_info
 {
-	sem_t		sem;
-	struct
-	{
 	key_t		key;
 	int			nsems;
-		sem_t		sem[SEMMAX];/* array of POSIX semaphores */
+	sem_t		sem[SEMMAX];	/* array of POSIX semaphores */
 	struct sem	semV[SEMMAX];	/* array of System V semaphore
 								 * structures */
 	struct pending_ops pendingOps[SEMMAX];	/* array of pending
 											 * operations */
-	}			set[SETMAX];
+};
+
+struct sem_info
+{
+	sem_t		sem;
+	int			nsets;
+	/* there are actually nsets of these: */
+	struct sem_set_info set[1];	/* VARIABLE LENGTH ARRAY */
 };
 
 static struct sem_info *SemInfo = (struct sem_info *) - 1;
@@ -78,7 +83,7 @@ semctl(int semid, int semnum, int cmd, /* ... */ union semun arg)
 
 	sem_wait(&SemInfo->sem);
 
-	if (semid < 0 || semid >= SETMAX ||
+	if (semid < 0 || semid >= SemInfo->nsets ||
 		semnum < 0 || semnum >= SemInfo->set[semid].nsems)
 	{
 		sem_post(&SemInfo->sem);
@@ -144,8 +149,10 @@ semget(key_t key, int nsems, int semflg)
 {
 	int			fd,
 				semid,
-				semnum /* , semnum1 */ ;
+				semnum,
+				nsets;
 	int			exist = 0;
+	Size		sem_info_size;
 	struct stat statbuf;
 
 	if (nsems < 0 || nsems > SEMMAX)
@@ -167,7 +174,9 @@ semget(key_t key, int nsems, int semflg)
 		if (fd == -1)
 			return fd;
 		/* The size may only be set once. Ignore errors. */
-		ltrunc(fd, sizeof(struct sem_info), SEEK_SET);
+		nsets = PROC_SEM_MAP_ENTRIES(MaxBackends);
+		sem_info_size = sizeof(struct sem_info) + (nsets-1) * sizeof(struct sem_set_info);
+		ltrunc(fd, sem_info_size, SEEK_SET);
 		if ( fstat( fd, &statbuf ) ) /* would be strange : the only doc'ed */
 		{                            /* error is EBADF */
 			close( fd );
@@ -177,50 +186,52 @@ semget(key_t key, int nsems, int semflg)
      * size is rounded by proc to the next __PAGESIZE
      */
     if ( statbuf.st_size != 
-         ((( sizeof(struct sem_info) /__PAGESIZE)+1) * __PAGESIZE) )
+         (((sem_info_size/__PAGESIZE)+1) * __PAGESIZE) )
     {
        fprintf( stderr,
          "Found a pre-existing shared memory block for the semaphore memory\n"
          "of a different size (%ld instead %ld). Make sure that all executables\n"
          "are from the same release or remove the file \"/dev/shmem/%s\"\n"
-         "left by a previous version.\n", statbuf.st_size,
-         sizeof(struct sem_info), SHM_INFO_NAME);
+         "left by a previous version.\n",
+				(long) statbuf.st_size,
+				(long) sem_info_size,
+				SHM_INFO_NAME);
          errno = EACCES;
        return -1;
     }
-		SemInfo = mmap(NULL, sizeof(struct sem_info),
+		SemInfo = mmap(NULL, sem_info_size,
 					   PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 		if (SemInfo == MAP_FAILED)
 			return -1;
 		if (!exist)
 		{
+			/* initialize shared memory */
+			memset(SemInfo, 0, sem_info_size);
+			SemInfo->nsets = nsets;
+			for (semid = 0; semid < nsets; semid++)
+				SemInfo->set[semid].key = -1;
 			/* create semaphore for locking */
 			sem_init(&SemInfo->sem, 1, 1);
-			sem_wait(&SemInfo->sem);
-			/* initilize shared memory */
-			memset(SemInfo->set, 0, sizeof(SemInfo->set));
-			for (semid = 0; semid < SETMAX; semid++)
-				SemInfo->set[semid].key = -1;
-			sem_post(&SemInfo->sem);
-      on_proc_exit( semclean, NULL );
+			on_proc_exit( semclean, 0 );
 		}
 	}
 
 	sem_wait(&SemInfo->sem);
+	nsets = SemInfo->nsets;
 
 	if (key != IPC_PRIVATE)
 	{
 		/* search existing element */
 		semid = 0;
-		while (semid < SETMAX && SemInfo->set[semid].key != key)
+		while (semid < nsets && SemInfo->set[semid].key != key)
 			semid++;
-		if (!(semflg & IPC_CREAT) && semid >= SETMAX)
+		if (!(semflg & IPC_CREAT) && semid >= nsets)
 		{
 			sem_post(&SemInfo->sem);
 			errno = ENOENT;
 			return -1;
 		}
-		else if (semid < SETMAX)
+		else if (semid < nsets)
 		{
 			if (semflg & IPC_CREAT && semflg & IPC_EXCL)
 			{
@@ -244,9 +255,9 @@ semget(key_t key, int nsems, int semflg)
 
 	/* search first free element */
 	semid = 0;
-	while (semid < SETMAX && SemInfo->set[semid].key != -1)
+	while (semid < nsets && SemInfo->set[semid].key != -1)
 		semid++;
-	if (semid >= SETMAX)
+	if (semid >= nsets)
 	{
 		sem_post(&SemInfo->sem);
 		errno = ENOSPC;
@@ -256,15 +267,18 @@ semget(key_t key, int nsems, int semflg)
 	for (semnum = 0; semnum < nsems; semnum++)
 	{
 		sem_init(&SemInfo->set[semid].sem[semnum], 1, 0);
-/* Currently sem_init always returns -1.
+/* Currently sem_init always returns -1. */
+#ifdef NOT_USED
 		if( sem_init( &SemInfo->set[semid].sem[semnum], 1, 0 ) == -1 )	{
+			int semnum1;
+
 			for( semnum1 = 0; semnum1 < semnum; semnum1++ )  {
 				sem_destroy( &SemInfo->set[semid].sem[semnum1] );
 			}
 			sem_post( &SemInfo->sem );
 			return -1;
 		}
-*/
+#endif
 	}
 
 	SemInfo->set[semid].key = key;
@@ -286,7 +300,7 @@ semop(int semid, struct sembuf * sops, size_t nsops)
 
 	sem_wait(&SemInfo->sem);
 
-	if (semid < 0 || semid >= SETMAX)
+	if (semid < 0 || semid >= SemInfo->nsets)
 	{
 		sem_post(&SemInfo->sem);
 		errno = EINVAL;

src/backend/postmaster/postmaster.c

@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.237 2001/08/30 19:02:42 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.238 2001/09/07 00:27:29 tgl Exp $
  *
  * NOTES
  *
@@ -138,9 +138,9 @@ char	   *UnixSocketDir;
 char	   *VirtualHost;
 
 /*
- * MaxBackends is the actual limit on the number of backends we will
- * start. The default is established by configure, but it can be
- * readjusted from 1..MAXBACKENDS with the postmaster -N switch. Note
+ * MaxBackends is the limit on the number of backends we can start.
+ * The default is established by configure, but it can be altered at
+ * postmaster start with the postmaster's -N switch.  Note
  * that a larger MaxBackends value will increase the size of the shared
  * memory area as well as cause the postmaster to grab more kernel
  * semaphores, even if you never actually use that many backends.
@@ -777,8 +777,8 @@ usage(const char *progname)
 #ifdef USE_SSL
 	printf(gettext("  -l              enable SSL connections\n"));
 #endif
-	printf(gettext("  -N MAX-CONNECT  maximum number of allowed connections (1..%d, default %d)\n"),
-		   MAXBACKENDS, DEF_MAXBACKENDS);
+	printf(gettext("  -N MAX-CONNECT  maximum number of allowed connections (default %d)\n"),
+		   DEF_MAXBACKENDS);
 	printf(gettext("  -o OPTIONS      pass 'OPTIONS' to each backend server\n"));
 	printf(gettext("  -p PORT         port number to listen on (default %d)\n"), DEF_PGPORT);
 	printf(gettext("  -S              silent mode (start in background without logging output)\n"));

src/backend/storage/ipc/shmem.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.57 2001/03/22 03:59:45 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.58 2001/09/07 00:27:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -259,92 +259,6 @@ ShmemInitHash(char *name,		/* table string name for shmem index */
 	return hash_create(init_size, infoP, hash_flags);
 }
 
-/*
- * ShmemPIDLookup -- lookup process data structure using process id
- *
- * Returns: TRUE if no error.  locationPtr is initialized if PID is
- *		found in the shmem index.
- *
- * NOTES:
- *		only information about success or failure is the value of
- *		locationPtr.
- */
-bool
-ShmemPIDLookup(int pid, SHMEM_OFFSET *locationPtr)
-{
-	ShmemIndexEnt *result,
-				item;
-	bool		found;
-
-	Assert(ShmemIndex);
-	MemSet(item.key, 0, SHMEM_INDEX_KEYSIZE);
-	sprintf(item.key, "PID %d", pid);
-
-	SpinAcquire(ShmemIndexLock);
-
-	result = (ShmemIndexEnt *)
-		hash_search(ShmemIndex, (char *) &item, HASH_ENTER, &found);
-
-	if (!result)
-	{
-		SpinRelease(ShmemIndexLock);
-		elog(ERROR, "ShmemInitPID: ShmemIndex corrupted");
-		return FALSE;
-	}
-
-	if (found)
-		*locationPtr = result->location;
-	else
-		result->location = *locationPtr;
-
-	SpinRelease(ShmemIndexLock);
-	return TRUE;
-}
-
-/*
- * ShmemPIDDestroy -- destroy shmem index entry for process
- *		using process id
- *
- * Returns: offset of the process struct in shared memory or
- *		INVALID_OFFSET if not found.
- *
- * Side Effect: removes the entry from the shmem index
- */
-SHMEM_OFFSET
-ShmemPIDDestroy(int pid)
-{
-	ShmemIndexEnt *result,
-				item;
-	bool		found;
-	SHMEM_OFFSET location = 0;
-
-	Assert(ShmemIndex);
-
-	MemSet(item.key, 0, SHMEM_INDEX_KEYSIZE);
-	sprintf(item.key, "PID %d", pid);
-
-	SpinAcquire(ShmemIndexLock);
-
-	result = (ShmemIndexEnt *)
-		hash_search(ShmemIndex, (char *) &item, HASH_REMOVE, &found);
-
-	if (found)
-		location = result->location;
-
-	SpinRelease(ShmemIndexLock);
-
-	if (!result)
-	{
-		elog(ERROR, "ShmemPIDDestroy: PID table corrupted");
-		return INVALID_OFFSET;
-	}
-
-	if (found)
-		return location;
-	else
-		return INVALID_OFFSET;
-}
-
 /*
  * ShmemInitStruct -- Create/attach to a structure in shared
  *		memory.
@@ -373,7 +287,6 @@ ShmemInitStruct(char *name, Size size, bool *foundPtr)
 
 	if (!ShmemIndex)
 	{
-
 		/*
 		 * If the shmem index doesn't exist, we are bootstrapping: we must
 		 * be trying to init the shmem index itself.
@@ -400,7 +313,6 @@ ShmemInitStruct(char *name, Size size, bool *foundPtr)
 
 	if (*foundPtr)
 	{
-
 		/*
 		 * Structure is in the shmem index so someone else has allocated
 		 * it already.	The size better be the same as the size we are

src/backend/storage/lmgr/lock.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.93 2001/08/29 19:14:39 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.94 2001/09/07 00:27:29 tgl Exp $
  *
  * NOTES
  *	  Outside modules can create a lock table and acquire/release
@@ -1430,7 +1430,6 @@ LockShmemSize(int maxBackends)
 void
 DumpLocks(void)
 {
-	SHMEM_OFFSET location;
 	PROC	   *proc;
 	SHM_QUEUE  *procHolders;
 	HOLDER	   *holder;
@@ -1438,12 +1437,10 @@ DumpLocks(void)
 	int			lockmethod = DEFAULT_LOCKMETHOD;
 	LOCKMETHODTABLE *lockMethodTable;
 
-	ShmemPIDLookup(MyProcPid, &location);
-	if (location == INVALID_OFFSET)
-		return;
-	proc = (PROC *) MAKE_PTR(location);
-	if (proc != MyProc)
+	proc = MyProc;
+	if (proc == NULL)
 		return;
+
 	procHolders = &proc->procHolders;
 
 	Assert(lockmethod < NumLockMethods);
@@ -1477,22 +1474,16 @@ DumpLocks(void)
 void
 DumpAllLocks(void)
 {
-	SHMEM_OFFSET location;
 	PROC	   *proc;
 	HOLDER	   *holder = NULL;
 	LOCK	   *lock;
-	int			pid;
 	int			lockmethod = DEFAULT_LOCKMETHOD;
 	LOCKMETHODTABLE *lockMethodTable;
 	HTAB	   *holderTable;
 	HASH_SEQ_STATUS status;
 
-	pid = getpid();
-	ShmemPIDLookup(pid, &location);
-	if (location == INVALID_OFFSET)
-		return;
-	proc = (PROC *) MAKE_PTR(location);
-	if (proc != MyProc)
+	proc = MyProc;
+	if (proc == NULL)
 		return;
 
 	Assert(lockmethod < NumLockMethods);

src/backend/storage/lmgr/proc.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.106 2001/09/04 21:42:17 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.107 2001/09/07 00:27:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -124,11 +124,18 @@ static void ProcFreeAllSemaphores(void);
 void
 InitProcGlobal(int maxBackends)
 {
+	int			semMapEntries;
+	Size		procGlobalSize;
 	bool		found = false;
 
-	/* attach to the free list */
+	/* Compute size for ProcGlobal structure */
+	Assert(maxBackends > 0);
+	semMapEntries = PROC_SEM_MAP_ENTRIES(maxBackends);
+	procGlobalSize = sizeof(PROC_HDR) + (semMapEntries-1) * sizeof(SEM_MAP_ENTRY);
+
+	/* Create or attach to the ProcGlobal shared structure */
 	ProcGlobal = (PROC_HDR *)
-		ShmemInitStruct("Proc Header", sizeof(PROC_HDR), &found);
+		ShmemInitStruct("Proc Header", procGlobalSize, &found);
 
 	/* --------------------
 	 * We're the first - initialize.
@@ -141,10 +148,12 @@ InitProcGlobal(int maxBackends)
 		int			i;
 
 		ProcGlobal->freeProcs = INVALID_OFFSET;
-		for (i = 0; i < PROC_SEM_MAP_ENTRIES; i++)
+		ProcGlobal->semMapEntries = semMapEntries;
+
+		for (i = 0; i < semMapEntries; i++)
 		{
-			ProcGlobal->procSemIds[i] = -1;
-			ProcGlobal->freeSemMap[i] = 0;
+			ProcGlobal->procSemMap[i].procSemId = -1;
+			ProcGlobal->procSemMap[i].freeSemMap = 0;
 		}
 
 		/*
@@ -157,11 +166,9 @@ InitProcGlobal(int maxBackends)
 		on_shmem_exit(ProcFreeAllSemaphores, 0);
 
 		/*
-		 * Pre-create the semaphores for the first maxBackends processes.
+		 * Pre-create the semaphores.
 		 */
-		Assert(maxBackends > 0 && maxBackends <= MAXBACKENDS);
-
-		for (i = 0; i < ((maxBackends - 1) / PROC_NSEMS_PER_SET + 1); i++)
+		for (i = 0; i < semMapEntries; i++)
 		{
 			IpcSemaphoreId semId;
 
@@ -169,7 +176,7 @@ InitProcGlobal(int maxBackends)
 									   IPCProtection,
 									   1,
 									   false);
-			ProcGlobal->procSemIds[i] = semId;
+			ProcGlobal->procSemMap[i].procSemId = semId;
 		}
 	}
 }
@@ -182,9 +189,17 @@ InitProcGlobal(int maxBackends)
 void
 InitProcess(void)
 {
-	bool		found = false;
-	unsigned long location,
-				myOffset;
+	SHMEM_OFFSET	myOffset;
+
+	/*
+	 * ProcGlobal should be set by a previous call to InitProcGlobal
+	 * (if we are a backend, we inherit this by fork() from the postmaster).
+	 */
+	if (ProcGlobal == NULL)
+		elog(STOP, "InitProcess: Proc Header uninitialized");
+
+	if (MyProc != NULL)
+		elog(ERROR, "InitProcess: you already exist");
 
 	/*
 	 * ProcStructLock protects the freelist of PROC entries and the map
@@ -196,27 +211,9 @@ InitProcess(void)
 	 * this routine, be careful to release the lock manually before any
 	 * elog(), else you'll have a stuck spinlock to add to your woes.
 	 */
-
 	SpinAcquire(ProcStructLock);
 
-	/* attach to the ProcGlobal structure */
-	ProcGlobal = (PROC_HDR *)
-		ShmemInitStruct("Proc Header", sizeof(PROC_HDR), &found);
-	if (!found)
-	{
-		/* this should not happen. InitProcGlobal() is called before this. */
-		SpinRelease(ProcStructLock);
-		elog(STOP, "InitProcess: Proc Header uninitialized");
-	}
-
-	if (MyProc != NULL)
-	{
-		SpinRelease(ProcStructLock);
-		elog(ERROR, "InitProcess: you already exist");
-	}
-
 	/* try to get a proc struct from the free list first */
-
 	myOffset = ProcGlobal->freeProcs;
 
 	if (myOffset != INVALID_OFFSET)
@@ -263,23 +260,6 @@ InitProcess(void)
 	MemSet(MyProc->sLocks, 0, sizeof(MyProc->sLocks));
 	MyProc->sLocks[ProcStructLock] = 1;
 
-	/*
-	 * Release the lock while accessing shmem index; we still haven't
-	 * installed ProcKill and so we don't want to hold lock if there's
-	 * an error.
-	 */
-	SpinRelease(ProcStructLock);
-
-	/*
-	 * Install ourselves in the shmem index table.	The name to use is
-	 * determined by the OS-assigned process id.  That allows the cleanup
-	 * process to find us after any untimely exit.
-	 */
-	location = MAKE_OFFSET(MyProc);
-	if ((!ShmemPIDLookup(MyProcPid, &location)) ||
-		(location != MAKE_OFFSET(MyProc)))
-		elog(STOP, "InitProcess: ShmemPID table broken");
-
 	/*
 	 * Arrange to clean up at backend exit.  Once we do this, owned
 	 * spinlocks will be released on exit, and so we can be a lot less
@@ -288,20 +268,21 @@ InitProcess(void)
 	on_shmem_exit(ProcKill, 0);
 
 	/*
-	 * Set up a wait-semaphore for the proc.  (Do this last so that we
-	 * can rely on ProcKill to clean up if it fails.)
+	 * Set up a wait-semaphore for the proc.  (We rely on ProcKill to clean
+	 * up if this fails.)
 	 */
 	if (IsUnderPostmaster)
-	{
-		SpinAcquire(ProcStructLock);
 		ProcGetNewSemIdAndNum(&MyProc->sem.semId, &MyProc->sem.semNum);
+
+	/* Done with freelist and sem map */
 	SpinRelease(ProcStructLock);
+
 	/*
 	 * We might be reusing a semaphore that belongs to a dead backend.
 	 * So be careful and reinitialize its value here.
 	 */
+	if (MyProc->sem.semId >= 0)
 		ZeroProcSemaphore(MyProc);
-	}
 
 	/*
 	 * Now that we have a PROC, we could try to acquire locks, so
@@ -416,9 +397,7 @@ ProcReleaseLocks(bool isCommit)
 static void
 ProcKill(void)
 {
-	SHMEM_OFFSET location;
-
-	Assert(MyProc);
+	Assert(MyProc != NULL);
 
 	/* Release any spinlocks I am holding */
 	ProcReleaseSpins(MyProc);
@@ -434,11 +413,6 @@ ProcKill(void)
 	LockReleaseAll(USER_LOCKMETHOD, MyProc, true, InvalidTransactionId);
 #endif
 
-	/* Remove my PROC struct from the shmem hash table */
-	location = ShmemPIDDestroy(MyProcPid);
-	Assert(location != INVALID_OFFSET);
-	Assert(MyProc == (PROC *) MAKE_PTR(location));
-
 	SpinAcquire(ProcStructLock);
 
 	/* Free up my wait semaphore, if I got one */
@@ -449,9 +423,10 @@ ProcKill(void)
 	MyProc->links.next = ProcGlobal->freeProcs;
 	ProcGlobal->freeProcs = MAKE_OFFSET(MyProc);
 
-	SpinRelease(ProcStructLock);
-
+	/* PROC struct isn't mine anymore; stop tracking spinlocks with it! */
 	MyProc = NULL;
+
+	SpinRelease(ProcStructLock);
 }
 
 
@@ -987,8 +962,8 @@ static void
 ProcGetNewSemIdAndNum(IpcSemaphoreId *semId, int *semNum)
 {
 	int			i;
-	IpcSemaphoreId *procSemIds = ProcGlobal->procSemIds;
-	int32	   *freeSemMap = ProcGlobal->freeSemMap;
+	int			semMapEntries = ProcGlobal->semMapEntries;
+	SEM_MAP_ENTRY  *procSemMap = ProcGlobal->procSemMap;
 	int32		fullmask = (1 << PROC_NSEMS_PER_SET) - 1;
 
 	/*
@@ -996,24 +971,24 @@ ProcGetNewSemIdAndNum(IpcSemaphoreId *semId, int *semNum)
 	 * the bitmap to look for a free semaphore.
 	 */
 
-	for (i = 0; i < PROC_SEM_MAP_ENTRIES; i++)
+	for (i = 0; i < semMapEntries; i++)
 	{
 		int			mask = 1;
 		int			j;
 
-		if (freeSemMap[i] == fullmask)
+		if (procSemMap[i].freeSemMap == fullmask)
 			continue;			/* this set is fully allocated */
-		if (procSemIds[i] < 0)
+		if (procSemMap[i].procSemId < 0)
 			continue;			/* this set hasn't been initialized */
 
 		for (j = 0; j < PROC_NSEMS_PER_SET; j++)
 		{
-			if ((freeSemMap[i] & mask) == 0)
+			if ((procSemMap[i].freeSemMap & mask) == 0)
 			{
 				/* A free semaphore found. Mark it as allocated. */
-				freeSemMap[i] |= mask;
+				procSemMap[i].freeSemMap |= mask;
 
-				*semId = procSemIds[i];
+				*semId = procSemMap[i].procSemId;
 				*semNum = j;
 				return;
 			}
@@ -1039,14 +1014,15 @@ ProcFreeSem(IpcSemaphoreId semId, int semNum)
 {
 	int32		mask;
 	int			i;
+	int			semMapEntries = ProcGlobal->semMapEntries;
 
 	mask = ~(1 << semNum);
 
-	for (i = 0; i < PROC_SEM_MAP_ENTRIES; i++)
+	for (i = 0; i < semMapEntries; i++)
 	{
-		if (ProcGlobal->procSemIds[i] == semId)
+		if (ProcGlobal->procSemMap[i].procSemId == semId)
 		{
-			ProcGlobal->freeSemMap[i] &= mask;
+			ProcGlobal->procSemMap[i].freeSemMap &= mask;
 			return;
 		}
 	}
@@ -1064,9 +1040,9 @@ ProcFreeAllSemaphores(void)
 {
 	int			i;
 
-	for (i = 0; i < PROC_SEM_MAP_ENTRIES; i++)
+	for (i = 0; i < ProcGlobal->semMapEntries; i++)
 	{
-		if (ProcGlobal->procSemIds[i] >= 0)
-			IpcSemaphoreKill(ProcGlobal->procSemIds[i]);
+		if (ProcGlobal->procSemMap[i].procSemId >= 0)
+			IpcSemaphoreKill(ProcGlobal->procSemMap[i].procSemId);
 	}
 }

src/backend/utils/init/postinit.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.89 2001/09/06 04:57:29 ishii Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.90 2001/09/07 00:27:29 tgl Exp $
  *
  *
  *-------------------------------------------------------------------------
@@ -281,7 +281,7 @@ InitPostgres(const char *dbname, const char *username)
 
 	InitBackendSharedInvalidationState();
 
-	if (MyBackendId > MAXBACKENDS || MyBackendId <= 0)
+	if (MyBackendId > MaxBackends || MyBackendId <= 0)
 		elog(FATAL, "InitPostgres: bad backend id %d", MyBackendId);
 
 	/*

src/backend/utils/misc/guc.c

@@ -4,7 +4,7 @@
  * Support for grand unified configuration scheme, including SET
  * command, configuration file, and command line options.
  *
- * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.46 2001/08/15 18:42:15 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.47 2001/09/07 00:27:29 tgl Exp $
  *
  * Copyright 2000 by PostgreSQL Global Development Group
  * Written by Peter Eisentraut <peter_e@gmx.net>.
@@ -286,7 +286,7 @@ static struct config_int
 	 * constraints here are partially unused.
 	 */
 	{"max_connections", PGC_POSTMASTER, &MaxBackends,
-	DEF_MAXBACKENDS, 1, MAXBACKENDS, NULL, NULL},
+	DEF_MAXBACKENDS, 1, INT_MAX, NULL, NULL},
 
 	{"shared_buffers", PGC_POSTMASTER, &NBuffers,
 	DEF_NBUFFERS, 16, INT_MAX, NULL, NULL},

src/include/pg_config.h.in

@@ -8,7 +8,7 @@
  * or in pg_config.h afterwards.  Of course, if you edit pg_config.h, then your
  * changes will be overwritten the next time you run configure.
  *
- * $Id: pg_config.h.in,v 1.3 2001/09/06 03:23:38 momjian Exp $
+ * $Id: pg_config.h.in,v 1.4 2001/09/07 00:27:29 tgl Exp $
  */
 
 #ifndef PG_CONFIG_H
@@ -106,12 +106,6 @@
  *------------------------------------------------------------------------
  */
 
-/*
- * 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)
-
 /*
  * Default number of buffers in shared buffer pool (each of size BLCKSZ).
  * This is just the default setting for the postmaster's -B switch.

src/include/storage/proc.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: proc.h,v 1.45 2001/07/06 21:04:26 tgl Exp $
+ * $Id: proc.h,v 1.46 2001/09/07 00:27:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -104,10 +104,21 @@ do { \
  * in each set for identification purposes.)
  *
  * PROC_SEM_MAP_ENTRIES is the number of semaphore sets we need to allocate
- * to keep track of up to MAXBACKENDS backends.
+ * to keep track of up to maxBackends backends.
  */
 #define  PROC_NSEMS_PER_SET		16
-#define  PROC_SEM_MAP_ENTRIES	((MAXBACKENDS-1)/PROC_NSEMS_PER_SET+1)
+#define  PROC_SEM_MAP_ENTRIES(maxBackends)	(((maxBackends)-1)/PROC_NSEMS_PER_SET+1)
+
+typedef struct
+{
+	/* info about a single set of per-process semaphores */
+	IpcSemaphoreId procSemId;
+	int32		freeSemMap;
+	/*
+	 * In freeSemMap, bit i is set if the i'th semaphore of this sema
+	 * set is allocated to a process.  (i counts from 0 at the LSB)
+	 */
+} SEM_MAP_ENTRY;
 
 typedef struct procglobal
 {
@@ -115,13 +126,12 @@ typedef struct procglobal
 	SHMEM_OFFSET freeProcs;
 
 	/* Info about semaphore sets used for per-process semaphores */
-	IpcSemaphoreId procSemIds[PROC_SEM_MAP_ENTRIES];
-	int32		freeSemMap[PROC_SEM_MAP_ENTRIES];
-
+	int			semMapEntries;
 	/*
-	 * In each freeSemMap entry, bit i is set if the i'th semaphore of the
-	 * set is allocated to a process.  (i counts from 0 at the LSB)
+	 * VARIABLE LENGTH ARRAY: actual length is semMapEntries.
+	 * THIS MUST BE LAST IN THE STRUCT DECLARATION.
 	 */
+	SEM_MAP_ENTRY	procSemMap[1];
 } PROC_HDR;
 
 /*

src/include/storage/shmem.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: shmem.h,v 1.29 2001/06/18 21:38:02 momjian Exp $
+ * $Id: shmem.h,v 1.30 2001/09/07 00:27:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -71,8 +71,6 @@ extern void *ShmemAlloc(Size size);
 extern bool ShmemIsValid(unsigned long addr);
 extern HTAB *ShmemInitHash(char *name, long init_size, long max_size,
 			  HASHCTL *infoP, int hash_flags);
-extern bool ShmemPIDLookup(int pid, SHMEM_OFFSET *locationPtr);
-extern SHMEM_OFFSET ShmemPIDDestroy(int pid);
 extern void *ShmemInitStruct(char *name, Size size, bool *foundPtr);