Revert the addition of GetMaxBackends() and related stuff.

This reverts commits 0147fc7, 4567596, aa64f23, and 5ecd018.
There is no longer agreement that introducing this function
was the right way to address the problem. The consensus now
seems to favor trying to make a correct value for MaxBackends
available to mdules executing their _PG_init() functions.

Nathan Bossart

Discussion: http://postgr.es/m/20220323045229.i23skfscdbvrsuxa@jrouhaud

1 files changed, 10 insertions, 13 deletions

diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
index ee2e15c17e9..5f5803f6814 100644
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -55,7 +55,7 @@
 int			max_locks_per_xact; /* set by guc.c */
 
 #define NLOCKENTS() \
-	mul_size(max_locks_per_xact, add_size(GetMaxBackends(), max_prepared_xacts))
+	mul_size(max_locks_per_xact, add_size(MaxBackends, max_prepared_xacts))
 
 
 /*
@@ -2924,7 +2924,6 @@ GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode, int *countp)
 	LWLock	   *partitionLock;
 	int			count = 0;
 	int			fast_count = 0;
-	int			max_backends = GetMaxBackends();
 
 	if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
 		elog(ERROR, "unrecognized lock method: %d", lockmethodid);
@@ -2943,12 +2942,12 @@ GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode, int *countp)
 			vxids = (VirtualTransactionId *)
 				MemoryContextAlloc(TopMemoryContext,
 								   sizeof(VirtualTransactionId) *
-								   (max_backends + max_prepared_xacts + 1));
+								   (MaxBackends + max_prepared_xacts + 1));
 	}
 	else
 		vxids = (VirtualTransactionId *)
 			palloc0(sizeof(VirtualTransactionId) *
-					(max_backends + max_prepared_xacts + 1));
+					(MaxBackends + max_prepared_xacts + 1));
 
 	/* Compute hash code and partition lock, and look up conflicting modes. */
 	hashcode = LockTagHashCode(locktag);
@@ -3105,7 +3104,7 @@ GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode, int *countp)
 
 	LWLockRelease(partitionLock);
 
-	if (count > max_backends + max_prepared_xacts)	/* should never happen */
+	if (count > MaxBackends + max_prepared_xacts)	/* should never happen */
 		elog(PANIC, "too many conflicting locks found");
 
 	vxids[count].backendId = InvalidBackendId;
@@ -3652,12 +3651,11 @@ GetLockStatusData(void)
 	int			els;
 	int			el;
 	int			i;
-	int			max_backends = GetMaxBackends();
 
 	data = (LockData *) palloc(sizeof(LockData));
 
 	/* Guess how much space we'll need. */
-	els = max_backends;
+	els = MaxBackends;
 	el = 0;
 	data->locks = (LockInstanceData *) palloc(sizeof(LockInstanceData) * els);
 
@@ -3691,7 +3689,7 @@ GetLockStatusData(void)
 
 			if (el >= els)
 			{
-				els += max_backends;
+				els += MaxBackends;
 				data->locks = (LockInstanceData *)
 					repalloc(data->locks, sizeof(LockInstanceData) * els);
 			}
@@ -3723,7 +3721,7 @@ GetLockStatusData(void)
 
 			if (el >= els)
 			{
-				els += max_backends;
+				els += MaxBackends;
 				data->locks = (LockInstanceData *)
 					repalloc(data->locks, sizeof(LockInstanceData) * els);
 			}
@@ -3852,7 +3850,7 @@ GetBlockerStatusData(int blocked_pid)
 	 * for the procs[] array; the other two could need enlargement, though.)
 	 */
 	data->nprocs = data->nlocks = data->npids = 0;
-	data->maxprocs = data->maxlocks = data->maxpids = GetMaxBackends();
+	data->maxprocs = data->maxlocks = data->maxpids = MaxBackends;
 	data->procs = (BlockedProcData *) palloc(sizeof(BlockedProcData) * data->maxprocs);
 	data->locks = (LockInstanceData *) palloc(sizeof(LockInstanceData) * data->maxlocks);
 	data->waiter_pids = (int *) palloc(sizeof(int) * data->maxpids);
@@ -3927,7 +3925,6 @@ GetSingleProcBlockerStatusData(PGPROC *blocked_proc, BlockedProcsData *data)
 	PGPROC	   *proc;
 	int			queue_size;
 	int			i;
-	int			max_backends = GetMaxBackends();
 
 	/* Nothing to do if this proc is not blocked */
 	if (theLock == NULL)
@@ -3956,7 +3953,7 @@ GetSingleProcBlockerStatusData(PGPROC *blocked_proc, BlockedProcsData *data)
 
 		if (data->nlocks >= data->maxlocks)
 		{
-			data->maxlocks += max_backends;
+			data->maxlocks += MaxBackends;
 			data->locks = (LockInstanceData *)
 				repalloc(data->locks, sizeof(LockInstanceData) * data->maxlocks);
 		}
@@ -3985,7 +3982,7 @@ GetSingleProcBlockerStatusData(PGPROC *blocked_proc, BlockedProcsData *data)
 
 	if (queue_size > data->maxpids - data->npids)
 	{
-		data->maxpids = Max(data->maxpids + max_backends,
+		data->maxpids = Max(data->maxpids + MaxBackends,
 							data->npids + queue_size);
 		data->waiter_pids = (int *) repalloc(data->waiter_pids,
 											 sizeof(int) * data->maxpids);