0002-Replace-ShmemAlloc-calls-by-ShmemInitStruct.patch

From 7341add1113ebfed5f160f664bc374165586229c Mon Sep 17 00:00:00 2001
From: Rahila Syed <rahilasyed.90@gmail.com>
Date: Sat, 1 Mar 2025 09:02:33 +0530
Subject: [PATCH 2/2] Replace ShmemAlloc calls by ShmemInitStruct

The shared memory allocated by ShmemAlloc is not tracked
by pg_shmem_allocations. This commit replaces most of the
calls to ShmemAlloc by ShmemInitStruct to associate a name
with the allocations and ensure that they get tracked by
pg_shmem_allocations
---
 src/backend/storage/lmgr/lwlock.c    |  1 +
 src/backend/storage/lmgr/predicate.c | 10 +++++-----
 src/backend/storage/lmgr/proc.c      |  8 ++++----
 3 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index 8adf273027..9101673185 100644
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -464,6 +464,7 @@ CreateLWLocks(void)
 		Size		spaceLocks = LWLockShmemSize();
 		int		   *LWLockCounter;
 		char	   *ptr;
+		bool found;
 
 		/* Allocate space */
 		ptr = (char *) ShmemAlloc(spaceLocks);
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
index 5b21a05398..58afb94d96 100644
--- a/src/backend/storage/lmgr/predicate.c
+++ b/src/backend/storage/lmgr/predicate.c
@@ -1244,7 +1244,7 @@ PredicateLockShmemInit(void)
 		PredXact->HavePartialClearedThrough = 0;
 		requestSize = mul_size((Size) max_table_size,
 							   sizeof(SERIALIZABLEXACT));
-		PredXact->element = ShmemAlloc(requestSize);
+		PredXact->element = ShmemInitStruct("SerializableXactList", requestSize, &found);
 		/* Add all elements to available list, clean. */
 		memset(PredXact->element, 0, requestSize);
 		for (i = 0; i < max_table_size; i++)
@@ -1299,9 +1299,11 @@ PredicateLockShmemInit(void)
 	 * probably OK.
 	 */
 	max_table_size *= 5;
+	requestSize = mul_size((Size) max_table_size,
+						RWConflictDataSize);
 
 	RWConflictPool = ShmemInitStruct("RWConflictPool",
-									 RWConflictPoolHeaderDataSize,
+									 RWConflictPoolHeaderDataSize + requestSize,
 									 &found);
 	Assert(found == IsUnderPostmaster);
 	if (!found)
@@ -1309,9 +1311,7 @@ PredicateLockShmemInit(void)
 		int			i;
 
 		dlist_init(&RWConflictPool->availableList);
-		requestSize = mul_size((Size) max_table_size,
-							   RWConflictDataSize);
-		RWConflictPool->element = ShmemAlloc(requestSize);
+		RWConflictPool->element = (RWConflict) ((char *)RWConflictPool + RWConflictPoolHeaderDataSize); 
 		/* Add all elements to available list, clean. */
 		memset(RWConflictPool->element, 0, requestSize);
 		for (i = 0; i < max_table_size; i++)
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 49204f91a2..e112735d93 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -218,11 +218,11 @@ InitProcGlobal(void)
 	 * how hotly they are accessed.
 	 */
 	ProcGlobal->xids =
-		(TransactionId *) ShmemAlloc(TotalProcs * sizeof(*ProcGlobal->xids));
+		(TransactionId *) ShmemInitStruct("Proc Transaction Ids", TotalProcs * sizeof(*ProcGlobal->xids), &found);
 	MemSet(ProcGlobal->xids, 0, TotalProcs * sizeof(*ProcGlobal->xids));
-	ProcGlobal->subxidStates = (XidCacheStatus *) ShmemAlloc(TotalProcs * sizeof(*ProcGlobal->subxidStates));
+	ProcGlobal->subxidStates = (XidCacheStatus *) ShmemInitStruct("Proc Sub-transaction id states", TotalProcs * sizeof(*ProcGlobal->subxidStates), &found);
 	MemSet(ProcGlobal->subxidStates, 0, TotalProcs * sizeof(*ProcGlobal->subxidStates));
-	ProcGlobal->statusFlags = (uint8 *) ShmemAlloc(TotalProcs * sizeof(*ProcGlobal->statusFlags));
+	ProcGlobal->statusFlags = (uint8 *) ShmemInitStruct("Proc Status Flags", TotalProcs * sizeof(*ProcGlobal->statusFlags), &found);
 	MemSet(ProcGlobal->statusFlags, 0, TotalProcs * sizeof(*ProcGlobal->statusFlags));
 
 	/*
@@ -233,7 +233,7 @@ InitProcGlobal(void)
 	fpLockBitsSize = MAXALIGN(FastPathLockGroupsPerBackend * sizeof(uint64));
 	fpRelIdSize = MAXALIGN(FastPathLockGroupsPerBackend * sizeof(Oid) * FP_LOCK_SLOTS_PER_GROUP);
 
-	fpPtr = ShmemAlloc(TotalProcs * (fpLockBitsSize + fpRelIdSize));
+	fpPtr = ShmemInitStruct("Fast path lock arrays", TotalProcs * (fpLockBitsSize + fpRelIdSize), &found);
 	MemSet(fpPtr, 0, TotalProcs * (fpLockBitsSize + fpRelIdSize));
 
 	/* For asserts checking we did not overflow. */
-- 
2.34.1