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

8 files changed, 63 insertions, 86 deletions

diff --git a/src/backend/storage/ipc/dsm.c b/src/backend/storage/ipc/dsm.c
index ce6f07d4c58..9d86bbe8724 100644
--- a/src/backend/storage/ipc/dsm.c
+++ b/src/backend/storage/ipc/dsm.c
@@ -166,7 +166,7 @@ dsm_postmaster_startup(PGShmemHeader *shim)
 
 	/* Determine size for new control segment. */
 	maxitems = PG_DYNSHMEM_FIXED_SLOTS
-		+ PG_DYNSHMEM_SLOTS_PER_BACKEND * GetMaxBackends();
+		+ PG_DYNSHMEM_SLOTS_PER_BACKEND * MaxBackends;
 	elog(DEBUG2, "dynamic shared memory system will support %u segments",
 		 maxitems);
 	segsize = dsm_control_bytes_needed(maxitems);
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index e184a3552c8..cb39fdde339 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -97,7 +97,7 @@ typedef struct ProcArrayStruct
 	/* oldest catalog xmin of any replication slot */
 	TransactionId replication_slot_catalog_xmin;
 
-	/* indexes into allProcs[], has ProcArrayMaxProcs entries */
+	/* indexes into allProcs[], has PROCARRAY_MAXPROCS entries */
 	int			pgprocnos[FLEXIBLE_ARRAY_MEMBER];
 } ProcArrayStruct;
 
@@ -355,17 +355,6 @@ static void MaintainLatestCompletedXidRecovery(TransactionId latestXid);
 static inline FullTransactionId FullXidRelativeTo(FullTransactionId rel,
 												  TransactionId xid);
 static void GlobalVisUpdateApply(ComputeXidHorizonsResult *horizons);
-static inline int GetProcArrayMaxProcs(void);
-
-
-/*
- * Retrieve the number of slots in the ProcArray structure.
- */
-static inline int
-GetProcArrayMaxProcs(void)
-{
-	return GetMaxBackends() + max_prepared_xacts;
-}
 
 /*
  * Report shared-memory space needed by CreateSharedProcArray.
@@ -376,8 +365,10 @@ ProcArrayShmemSize(void)
 	Size		size;
 
 	/* Size of the ProcArray structure itself */
+#define PROCARRAY_MAXPROCS	(MaxBackends + max_prepared_xacts)
+
 	size = offsetof(ProcArrayStruct, pgprocnos);
-	size = add_size(size, mul_size(sizeof(int), GetProcArrayMaxProcs()));
+	size = add_size(size, mul_size(sizeof(int), PROCARRAY_MAXPROCS));
 
 	/*
 	 * During Hot Standby processing we have a data structure called
@@ -393,7 +384,7 @@ ProcArrayShmemSize(void)
 	 * shared memory is being set up.
 	 */
 #define TOTAL_MAX_CACHED_SUBXIDS \
-	((PGPROC_MAX_CACHED_SUBXIDS + 1) * GetProcArrayMaxProcs())
+	((PGPROC_MAX_CACHED_SUBXIDS + 1) * PROCARRAY_MAXPROCS)
 
 	if (EnableHotStandby)
 	{
@@ -420,7 +411,7 @@ CreateSharedProcArray(void)
 		ShmemInitStruct("Proc Array",
 						add_size(offsetof(ProcArrayStruct, pgprocnos),
 								 mul_size(sizeof(int),
-										  GetProcArrayMaxProcs())),
+										  PROCARRAY_MAXPROCS)),
 						&found);
 
 	if (!found)
@@ -429,7 +420,7 @@ CreateSharedProcArray(void)
 		 * We're the first - initialize.
 		 */
 		procArray->numProcs = 0;
-		procArray->maxProcs = GetProcArrayMaxProcs();
+		procArray->maxProcs = PROCARRAY_MAXPROCS;
 		procArray->maxKnownAssignedXids = TOTAL_MAX_CACHED_SUBXIDS;
 		procArray->numKnownAssignedXids = 0;
 		procArray->tailKnownAssignedXids = 0;
@@ -4645,7 +4636,7 @@ KnownAssignedXidsCompress(bool force)
 		 */
 		int			nelements = head - tail;
 
-		if (nelements < 4 * GetProcArrayMaxProcs() ||
+		if (nelements < 4 * PROCARRAY_MAXPROCS ||
 			nelements < 2 * pArray->numKnownAssignedXids)
 			return;
 	}
diff --git a/src/backend/storage/ipc/procsignal.c b/src/backend/storage/ipc/procsignal.c
index f41563a0a48..00d66902d8b 100644
--- a/src/backend/storage/ipc/procsignal.c
+++ b/src/backend/storage/ipc/procsignal.c
@@ -81,6 +81,13 @@ typedef struct
 	ProcSignalSlot psh_slot[FLEXIBLE_ARRAY_MEMBER];
 } ProcSignalHeader;
 
+/*
+ * We reserve a slot for each possible BackendId, plus one for each
+ * possible auxiliary process type.  (This scheme assumes there is not
+ * more than one of any auxiliary process type at a time.)
+ */
+#define NumProcSignalSlots	(MaxBackends + NUM_AUXPROCTYPES)
+
 /* Check whether the relevant type bit is set in the flags. */
 #define BARRIER_SHOULD_CHECK(flags, type) \
 	(((flags) & (((uint32) 1) << (uint32) (type))) != 0)
@@ -95,20 +102,6 @@ static ProcSignalSlot *MyProcSignalSlot = NULL;
 static bool CheckProcSignal(ProcSignalReason reason);
 static void CleanupProcSignalState(int status, Datum arg);
 static void ResetProcSignalBarrierBits(uint32 flags);
-static inline int GetNumProcSignalSlots(void);
-
-/*
- * GetNumProcSignalSlots
- *
- * We reserve a slot for each possible BackendId, plus one for each possible
- * auxiliary process type.  (This scheme assume there is not more than one of
- * any auxiliary process type at a time.)
- */
-static inline int
-GetNumProcSignalSlots(void)
-{
-	return GetMaxBackends() + NUM_AUXPROCTYPES;
-}
 
 /*
  * ProcSignalShmemSize
@@ -119,7 +112,7 @@ ProcSignalShmemSize(void)
 {
 	Size		size;
 
-	size = mul_size(GetNumProcSignalSlots(), sizeof(ProcSignalSlot));
+	size = mul_size(NumProcSignalSlots, sizeof(ProcSignalSlot));
 	size = add_size(size, offsetof(ProcSignalHeader, psh_slot));
 	return size;
 }
@@ -133,7 +126,6 @@ ProcSignalShmemInit(void)
 {
 	Size		size = ProcSignalShmemSize();
 	bool		found;
-	int			numProcSignalSlots = GetNumProcSignalSlots();
 
 	ProcSignal = (ProcSignalHeader *)
 		ShmemInitStruct("ProcSignal", size, &found);
@@ -145,7 +137,7 @@ ProcSignalShmemInit(void)
 
 		pg_atomic_init_u64(&ProcSignal->psh_barrierGeneration, 0);
 
-		for (i = 0; i < numProcSignalSlots; ++i)
+		for (i = 0; i < NumProcSignalSlots; ++i)
 		{
 			ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
 
@@ -171,7 +163,7 @@ ProcSignalInit(int pss_idx)
 	ProcSignalSlot *slot;
 	uint64		barrier_generation;
 
-	Assert(pss_idx >= 1 && pss_idx <= GetNumProcSignalSlots());
+	Assert(pss_idx >= 1 && pss_idx <= NumProcSignalSlots);
 
 	slot = &ProcSignal->psh_slot[pss_idx - 1];
 
@@ -300,7 +292,7 @@ SendProcSignal(pid_t pid, ProcSignalReason reason, BackendId backendId)
 		 */
 		int			i;
 
-		for (i = GetNumProcSignalSlots() - 1; i >= 0; i--)
+		for (i = NumProcSignalSlots - 1; i >= 0; i--)
 		{
 			slot = &ProcSignal->psh_slot[i];
 
@@ -341,7 +333,6 @@ EmitProcSignalBarrier(ProcSignalBarrierType type)
 {
 	uint32		flagbit = 1 << (uint32) type;
 	uint64		generation;
-	int			numProcSignalSlots = GetNumProcSignalSlots();
 
 	/*
 	 * Set all the flags.
@@ -351,7 +342,7 @@ EmitProcSignalBarrier(ProcSignalBarrierType type)
 	 * anything that we do afterwards. (This is also true of the later call to
 	 * pg_atomic_add_fetch_u64.)
 	 */
-	for (int i = 0; i < numProcSignalSlots; i++)
+	for (int i = 0; i < NumProcSignalSlots; i++)
 	{
 		volatile ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
 
@@ -377,7 +368,7 @@ EmitProcSignalBarrier(ProcSignalBarrierType type)
 	 * backends that need to update state - but they won't actually need to
 	 * change any state.
 	 */
-	for (int i = numProcSignalSlots - 1; i >= 0; i--)
+	for (int i = NumProcSignalSlots - 1; i >= 0; i--)
 	{
 		volatile ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
 		pid_t		pid = slot->pss_pid;
@@ -402,7 +393,7 @@ WaitForProcSignalBarrier(uint64 generation)
 {
 	Assert(generation <= pg_atomic_read_u64(&ProcSignal->psh_barrierGeneration));
 
-	for (int i = GetNumProcSignalSlots() - 1; i >= 0; i--)
+	for (int i = NumProcSignalSlots - 1; i >= 0; i--)
 	{
 		ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
 		uint64		oldval;
diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 2dec668bbcd..2861c03e04b 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -213,7 +213,7 @@ SInvalShmemSize(void)
 	 * free slot. This is because the autovacuum launcher and worker processes,
 	 * which are included in MaxBackends, are not started in Hot Standby mode.
 	 */
-	size = add_size(size, mul_size(sizeof(ProcState), GetMaxBackends()));
+	size = add_size(size, mul_size(sizeof(ProcState), MaxBackends));
 
 	return size;
 }
@@ -239,7 +239,7 @@ CreateSharedInvalidationState(void)
 	shmInvalBuffer->maxMsgNum = 0;
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
 	shmInvalBuffer->lastBackend = 0;
-	shmInvalBuffer->maxBackends = GetMaxBackends();
+	shmInvalBuffer->maxBackends = MaxBackends;
 	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
diff --git a/src/backend/storage/lmgr/deadlock.c b/src/backend/storage/lmgr/deadlock.c
index b5d539ba5d9..cd9c0418eca 100644
--- a/src/backend/storage/lmgr/deadlock.c
+++ b/src/backend/storage/lmgr/deadlock.c
@@ -143,7 +143,6 @@ void
 InitDeadLockChecking(void)
 {
 	MemoryContext oldcxt;
-	int max_backends = GetMaxBackends();
 
 	/* Make sure allocations are permanent */
 	oldcxt = MemoryContextSwitchTo(TopMemoryContext);
@@ -152,16 +151,16 @@ InitDeadLockChecking(void)
 	 * FindLockCycle needs at most MaxBackends entries in visitedProcs[] and
 	 * deadlockDetails[].
 	 */
-	visitedProcs = (PGPROC **) palloc(max_backends * sizeof(PGPROC *));
-	deadlockDetails = (DEADLOCK_INFO *) palloc(max_backends * sizeof(DEADLOCK_INFO));
+	visitedProcs = (PGPROC **) palloc(MaxBackends * sizeof(PGPROC *));
+	deadlockDetails = (DEADLOCK_INFO *) palloc(MaxBackends * sizeof(DEADLOCK_INFO));
 
 	/*
 	 * TopoSort needs to consider at most MaxBackends wait-queue entries, and
 	 * it needn't run concurrently with FindLockCycle.
 	 */
 	topoProcs = visitedProcs;	/* re-use this space */
-	beforeConstraints = (int *) palloc(max_backends * sizeof(int));
-	afterConstraints = (int *) palloc(max_backends * sizeof(int));
+	beforeConstraints = (int *) palloc(MaxBackends * sizeof(int));
+	afterConstraints = (int *) palloc(MaxBackends * sizeof(int));
 
 	/*
 	 * We need to consider rearranging at most MaxBackends/2 wait queues
@@ -170,8 +169,8 @@ InitDeadLockChecking(void)
 	 * MaxBackends total waiters.
 	 */
 	waitOrders = (WAIT_ORDER *)
-		palloc((max_backends / 2) * sizeof(WAIT_ORDER));
-	waitOrderProcs = (PGPROC **) palloc(max_backends * sizeof(PGPROC *));
+		palloc((MaxBackends / 2) * sizeof(WAIT_ORDER));
+	waitOrderProcs = (PGPROC **) palloc(MaxBackends * sizeof(PGPROC *));
 
 	/*
 	 * Allow at most MaxBackends distinct constraints in a configuration. (Is
@@ -181,7 +180,7 @@ InitDeadLockChecking(void)
 	 * limits the maximum recursion depth of DeadLockCheckRecurse. Making it
 	 * really big might potentially allow a stack-overflow problem.
 	 */
-	maxCurConstraints = max_backends;
+	maxCurConstraints = MaxBackends;
 	curConstraints = (EDGE *) palloc(maxCurConstraints * sizeof(EDGE));
 
 	/*
@@ -192,7 +191,7 @@ InitDeadLockChecking(void)
 	 * last MaxBackends entries in possibleConstraints[] are reserved as
 	 * output workspace for FindLockCycle.
 	 */
-	maxPossibleConstraints = max_backends * 4;
+	maxPossibleConstraints = MaxBackends * 4;
 	possibleConstraints =
 		(EDGE *) palloc(maxPossibleConstraints * sizeof(EDGE));
 
@@ -328,7 +327,7 @@ DeadLockCheckRecurse(PGPROC *proc)
 	if (nCurConstraints >= maxCurConstraints)
 		return true;			/* out of room for active constraints? */
 	oldPossibleConstraints = nPossibleConstraints;
-	if (nPossibleConstraints + nEdges + GetMaxBackends() <= maxPossibleConstraints)
+	if (nPossibleConstraints + nEdges + MaxBackends <= maxPossibleConstraints)
 	{
 		/* We can save the edge list in possibleConstraints[] */
 		nPossibleConstraints += nEdges;
@@ -389,7 +388,7 @@ TestConfiguration(PGPROC *startProc)
 	/*
 	 * Make sure we have room for FindLockCycle's output.
 	 */
-	if (nPossibleConstraints + GetMaxBackends() > maxPossibleConstraints)
+	if (nPossibleConstraints + MaxBackends > maxPossibleConstraints)
 		return -1;
 
 	/*
@@ -487,7 +486,7 @@ FindLockCycleRecurse(PGPROC *checkProc,
 				 * record total length of cycle --- outer levels will now fill
 				 * deadlockDetails[]
 				 */
-				Assert(depth <= GetMaxBackends());
+				Assert(depth <= MaxBackends);
 				nDeadlockDetails = depth;
 
 				return true;
@@ -501,7 +500,7 @@ FindLockCycleRecurse(PGPROC *checkProc,
 		}
 	}
 	/* Mark proc as seen */
-	Assert(nVisitedProcs < GetMaxBackends());
+	Assert(nVisitedProcs < MaxBackends);
 	visitedProcs[nVisitedProcs++] = checkProc;
 
 	/*
@@ -699,7 +698,7 @@ FindLockCycleRecurseMember(PGPROC *checkProc,
 					/*
 					 * Add this edge to the list of soft edges in the cycle
 					 */
-					Assert(*nSoftEdges < GetMaxBackends());
+					Assert(*nSoftEdges < MaxBackends);
 					softEdges[*nSoftEdges].waiter = checkProcLeader;
 					softEdges[*nSoftEdges].blocker = leader;
 					softEdges[*nSoftEdges].lock = lock;
@@ -772,7 +771,7 @@ FindLockCycleRecurseMember(PGPROC *checkProc,
 					/*
 					 * Add this edge to the list of soft edges in the cycle
 					 */
-					Assert(*nSoftEdges < GetMaxBackends());
+					Assert(*nSoftEdges < MaxBackends);
 					softEdges[*nSoftEdges].waiter = checkProcLeader;
 					softEdges[*nSoftEdges].blocker = leader;
 					softEdges[*nSoftEdges].lock = lock;
@@ -835,7 +834,7 @@ ExpandConstraints(EDGE *constraints,
 		waitOrders[nWaitOrders].procs = waitOrderProcs + nWaitOrderProcs;
 		waitOrders[nWaitOrders].nProcs = lock->waitProcs.size;
 		nWaitOrderProcs += lock->waitProcs.size;
-		Assert(nWaitOrderProcs <= GetMaxBackends());
+		Assert(nWaitOrderProcs <= MaxBackends);
 
 		/*
 		 * Do the topo sort.  TopoSort need not examine constraints after this
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);
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
index e337aad5b24..25e7e4e37bf 100644
--- a/src/backend/storage/lmgr/predicate.c
+++ b/src/backend/storage/lmgr/predicate.c
@@ -257,7 +257,7 @@
 	(&MainLWLockArray[PREDICATELOCK_MANAGER_LWLOCK_OFFSET + (i)].lock)
 
 #define NPREDICATELOCKTARGETENTS() \
-	mul_size(max_predicate_locks_per_xact, add_size(GetMaxBackends(), max_prepared_xacts))
+	mul_size(max_predicate_locks_per_xact, add_size(MaxBackends, max_prepared_xacts))
 
 #define SxactIsOnFinishedList(sxact) (!SHMQueueIsDetached(&((sxact)->finishedLink)))
 
@@ -1222,7 +1222,7 @@ InitPredicateLocks(void)
 	 * Compute size for serializable transaction hashtable. Note these
 	 * calculations must agree with PredicateLockShmemSize!
 	 */
-	max_table_size = (GetMaxBackends() + max_prepared_xacts);
+	max_table_size = (MaxBackends + max_prepared_xacts);
 
 	/*
 	 * Allocate a list to hold information on transactions participating in
@@ -1375,7 +1375,7 @@ PredicateLockShmemSize(void)
 	size = add_size(size, size / 10);
 
 	/* transaction list */
-	max_table_size = GetMaxBackends() + max_prepared_xacts;
+	max_table_size = MaxBackends + max_prepared_xacts;
 	max_table_size *= 10;
 	size = add_size(size, PredXactListDataSize);
 	size = add_size(size, mul_size((Size) max_table_size,
@@ -1907,7 +1907,7 @@ GetSerializableTransactionSnapshotInt(Snapshot snapshot,
 	{
 		++(PredXact->WritableSxactCount);
 		Assert(PredXact->WritableSxactCount <=
-			   (GetMaxBackends() + max_prepared_xacts));
+			   (MaxBackends + max_prepared_xacts));
 	}
 
 	MySerializableXact = sxact;
@@ -5111,7 +5111,7 @@ predicatelock_twophase_recover(TransactionId xid, uint16 info,
 		{
 			++(PredXact->WritableSxactCount);
 			Assert(PredXact->WritableSxactCount <=
-				   (GetMaxBackends() + max_prepared_xacts));
+				   (MaxBackends + max_prepared_xacts));
 		}
 
 		/*
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 93d082c45ee..37aaab13381 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -103,7 +103,7 @@ ProcGlobalShmemSize(void)
 {
 	Size		size = 0;
 	Size		TotalProcs =
-	add_size(GetMaxBackends(), add_size(NUM_AUXILIARY_PROCS, max_prepared_xacts));
+	add_size(MaxBackends, add_size(NUM_AUXILIARY_PROCS, max_prepared_xacts));
 
 	/* ProcGlobal */
 	size = add_size(size, sizeof(PROC_HDR));
@@ -127,7 +127,7 @@ ProcGlobalSemas(void)
 	 * We need a sema per backend (including autovacuum), plus one for each
 	 * auxiliary process.
 	 */
-	return GetMaxBackends() + NUM_AUXILIARY_PROCS;
+	return MaxBackends + NUM_AUXILIARY_PROCS;
 }
 
 /*
@@ -162,8 +162,7 @@ InitProcGlobal(void)
 	int			i,
 				j;
 	bool		found;
-	int			max_backends = GetMaxBackends();
-	uint32		TotalProcs = max_backends + NUM_AUXILIARY_PROCS + max_prepared_xacts;
+	uint32		TotalProcs = MaxBackends + NUM_AUXILIARY_PROCS + max_prepared_xacts;
 
 	/* Create the ProcGlobal shared structure */
 	ProcGlobal = (PROC_HDR *)
@@ -196,7 +195,7 @@ InitProcGlobal(void)
 	MemSet(procs, 0, TotalProcs * sizeof(PGPROC));
 	ProcGlobal->allProcs = procs;
 	/* XXX allProcCount isn't really all of them; it excludes prepared xacts */
-	ProcGlobal->allProcCount = max_backends + NUM_AUXILIARY_PROCS;
+	ProcGlobal->allProcCount = MaxBackends + NUM_AUXILIARY_PROCS;
 
 	/*
 	 * Allocate arrays mirroring PGPROC fields in a dense manner. See
@@ -222,7 +221,7 @@ InitProcGlobal(void)
 		 * dummy PGPROCs don't need these though - they're never associated
 		 * with a real process
 		 */
-		if (i < max_backends + NUM_AUXILIARY_PROCS)
+		if (i < MaxBackends + NUM_AUXILIARY_PROCS)
 		{
 			procs[i].sem = PGSemaphoreCreate();
 			InitSharedLatch(&(procs[i].procLatch));
@@ -259,7 +258,7 @@ InitProcGlobal(void)
 			ProcGlobal->bgworkerFreeProcs = &procs[i];
 			procs[i].procgloballist = &ProcGlobal->bgworkerFreeProcs;
 		}
-		else if (i < max_backends)
+		else if (i < MaxBackends)
 		{
 			/* PGPROC for walsender, add to walsenderFreeProcs list */
 			procs[i].links.next = (SHM_QUEUE *) ProcGlobal->walsenderFreeProcs;
@@ -287,8 +286,8 @@ InitProcGlobal(void)
 	 * Save pointers to the blocks of PGPROC structures reserved for auxiliary
 	 * processes and prepared transactions.
 	 */
-	AuxiliaryProcs = &procs[max_backends];
-	PreparedXactProcs = &procs[max_backends + NUM_AUXILIARY_PROCS];
+	AuxiliaryProcs = &procs[MaxBackends];
+	PreparedXactProcs = &procs[MaxBackends + NUM_AUXILIARY_PROCS];
 
 	/* Create ProcStructLock spinlock, too */
 	ProcStructLock = (slock_t *) ShmemAlloc(sizeof(slock_t));