agora inbox for [email protected]  

help / color / mirror / Atom feed

[PATCH v45 4/8] Use BulkInsertState when copying data to the new heap.
67+ messages / 2 participants
[nested] [flat]

* [PATCH v45 4/8] Use BulkInsertState when copying data to the new heap.
@ 2026-03-11 14:20 Antonin Houska <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Antonin Houska @ 2026-03-11 14:20 UTC (permalink / raw)

It should make the copying more efficient. Besides that, buffer access
strategy is involved this way.

This diff reverts the changes done in previous parts of the series to
reform_and_rewrite_tuple() and introduces a separate function
heap_insert_for_repack().
---
 src/backend/access/heap/heapam_handler.c | 110 +++++++++++++++--------
 1 file changed, 72 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 0ba7c0df1fc..fa95deb46ea 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -51,6 +51,11 @@
 static void reform_and_rewrite_tuple(HeapTuple tuple,
 									 Relation OldHeap, Relation NewHeap,
 									 Datum *values, bool *isnull, RewriteState rwstate);
+static void heap_insert_for_repack(HeapTuple tuple, Relation OldHeap,
+								   Relation NewHeap, Datum *values, bool *isnull,
+								   BulkInsertState bistate);
+static HeapTuple reform_tuple(HeapTuple tuple, Relation OldHeap,
+							  Relation NewHeap, Datum *values, bool *isnull);
 
 static bool SampleHeapTupleVisible(TableScanDesc scan, Buffer buffer,
 								   HeapTuple tuple,
@@ -703,6 +708,7 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 								 double *tups_recently_dead)
 {
 	RewriteState rwstate = NULL;
+	BulkInsertState	bistate = NULL;
 	IndexScanDesc indexScan;
 	TableScanDesc tableScan;
 	HeapScanDesc heapScan;
@@ -738,6 +744,8 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 	if (!concurrent)
 		rwstate = begin_heap_rewrite(OldHeap, NewHeap, OldestXmin,
 									 *xid_cutoff, *multi_cutoff);
+	else
+		bistate = GetBulkInsertState();
 
 
 	/* Set up sorting if wanted */
@@ -967,8 +975,12 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 			};
 			int64		ct_val[2];
 
-			reform_and_rewrite_tuple(tuple, OldHeap, NewHeap,
-									 values, isnull, rwstate);
+			if (!concurrent)
+				reform_and_rewrite_tuple(tuple, OldHeap, NewHeap,
+										 values, isnull, rwstate);
+			else
+				heap_insert_for_repack(tuple, OldHeap, NewHeap,
+									   values, isnull, bistate);
 
 			/*
 			 * In indexscan mode and also VACUUM FULL, report increase in
@@ -1016,10 +1028,15 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 				break;
 
 			n_tuples += 1;
-			reform_and_rewrite_tuple(tuple,
-									 OldHeap, NewHeap,
-									 values, isnull,
-									 rwstate);
+			if (!concurrent)
+				reform_and_rewrite_tuple(tuple,
+										 OldHeap, NewHeap,
+										 values, isnull,
+										 rwstate);
+			else
+				heap_insert_for_repack(tuple, OldHeap, NewHeap,
+									   values, isnull, bistate);
+
 			/* Report n_tuples */
 			pgstat_progress_update_param(PROGRESS_REPACK_HEAP_TUPLES_INSERTED,
 										 n_tuples);
@@ -1031,6 +1048,8 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 	/* Write out any remaining tuples, and fsync if needed */
 	if (rwstate)
 		end_heap_rewrite(rwstate);
+	if (bistate)
+		FreeBulkInsertState(bistate);
 
 	/* Clean up */
 	pfree(values);
@@ -2423,56 +2442,71 @@ heapam_scan_sample_next_tuple(TableScanDesc scan, SampleScanState *scanstate,
  * SET WITHOUT OIDS.
  *
  * So, we must reconstruct the tuple from component Datums.
- *
- * If rwstate=NULL, use simple_heap_insert() instead of rewriting - in that
- * case we still need to deform/form the tuple. TODO Shouldn't we rename the
- * function, as might not do any rewrite?
  */
 static void
 reform_and_rewrite_tuple(HeapTuple tuple,
 						 Relation OldHeap, Relation NewHeap,
 						 Datum *values, bool *isnull, RewriteState rwstate)
+{
+	HeapTuple       copiedTuple;
+
+	copiedTuple = reform_tuple(tuple, OldHeap, NewHeap, values, isnull);
+
+	/* The heap rewrite module does the rest */
+	rewrite_heap_tuple(rwstate, tuple, copiedTuple);
+
+	heap_freetuple(copiedTuple);
+}
+
+/*
+ * Insert tuple when processing REPACK CONCURRENTLY.
+ *
+ * rewriteheap.c is not used in the CONCURRENTLY case because it'd be
+ * difficult to do the same in the catch-up phase (as the logical
+ * decoding does not provide us with sufficient visibility
+ * information). Thus we must use heap_insert() both during the
+ * catch-up and here.
+ *
+ * We pass the NO_LOGICAL flag to heap_insert() in order to skip logical
+ * decoding: as soon as REPACK CONCURRENTLY swaps the relation files, it drops
+ * this relation, so no logical replication subscription should need the data.
+ *
+ * BulkInsertState is used because many tuples are inserted in the typical
+ * case.
+ */
+static void
+heap_insert_for_repack(HeapTuple tuple, Relation OldHeap, Relation NewHeap,
+					   Datum *values, bool *isnull, BulkInsertState bistate)
+{
+	tuple = reform_tuple(tuple, OldHeap, NewHeap, values, isnull);
+
+	heap_insert(NewHeap, tuple, GetCurrentCommandId(true),
+				HEAP_INSERT_NO_LOGICAL, bistate);
+
+	heap_freetuple(tuple);
+}
+
+/*
+ * Deform tuple, set values of dropped columns to NULL, form a new tuple and
+ * return it.
+ */
+static HeapTuple
+reform_tuple(HeapTuple tuple, Relation OldHeap, Relation NewHeap,
+			 Datum *values, bool *isnull)
 {
 	TupleDesc	oldTupDesc = RelationGetDescr(OldHeap);
 	TupleDesc	newTupDesc = RelationGetDescr(NewHeap);
-	HeapTuple	copiedTuple;
 	int			i;
 
 	heap_deform_tuple(tuple, oldTupDesc, values, isnull);
 
-	/* Be sure to null out any dropped columns */
 	for (i = 0; i < newTupDesc->natts; i++)
 	{
 		if (TupleDescCompactAttr(newTupDesc, i)->attisdropped)
 			isnull[i] = true;
 	}
 
-	copiedTuple = heap_form_tuple(newTupDesc, values, isnull);
-
-	if (rwstate)
-		/* The heap rewrite module does the rest */
-		rewrite_heap_tuple(rwstate, tuple, copiedTuple);
-	else
-	{
-		/*
-		 * Insert tuple when processing REPACK CONCURRENTLY.
-		 *
-		 * rewriteheap.c is not used in the CONCURRENTLY case because it'd be
-		 * difficult to do the same in the catch-up phase (as the logical
-		 * decoding does not provide us with sufficient visibility
-		 * information). Thus we must use heap_insert() both during the
-		 * catch-up and here.
-		 *
-		 * The following is like simple_heap_insert() except that we pass the
-		 * flag to skip logical decoding: as soon as REPACK CONCURRENTLY swaps
-		 * the relation files, it drops this relation, so no logical
-		 * replication subscription should need the data.
-		 */
-		heap_insert(NewHeap, copiedTuple, GetCurrentCommandId(true),
-					HEAP_INSERT_NO_LOGICAL, NULL);
-	}
-
-	heap_freetuple(copiedTuple);
+	return heap_form_tuple(newTupDesc, values, isnull);
 }
 
 /*
-- 
2.47.3


--cldir6umqisr673d
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
	filename="v45-0005-rename-cluster.c-h-to-repack.c-h.patch"



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic
@ 2026-07-09 19:20 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 67+ messages in thread

From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw)

---
 src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++-------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 37a21ffaf1a..17e98c9efdc 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -24,7 +24,6 @@
 #include "storage/procsignal.h"
 #include "storage/shmem.h"
 #include "storage/sinvaladt.h"
-#include "storage/spin.h"
 #include "storage/subsystems.h"
 
 /*
@@ -87,19 +86,10 @@
  * has no need to touch anyone's ProcState, except in the infrequent cases
  * when SICleanupQueue is needed.  The only point of overlap is that
  * the writer wants to change maxMsgNum while readers need to read it.
- * We deal with that by having a spinlock that readers must take for just
- * long enough to read maxMsgNum, while writers take it for just long enough
- * to write maxMsgNum.  (The exact rule is that you need the spinlock to
- * read maxMsgNum if you are not holding SInvalWriteLock, and you need the
- * spinlock to write maxMsgNum unless you are holding both locks.)
- *
- * Note: since maxMsgNum is an int and hence presumably atomically readable/
- * writable, the spinlock might seem unnecessary.  The reason it is needed
- * is to provide a memory barrier: we need to be sure that messages written
- * to the array are actually there before maxMsgNum is increased, and that
- * readers will see that data after fetching maxMsgNum.  Multiprocessors
- * that have weak memory-ordering guarantees can fail without the memory
- * barrier instructions that are included in the spinlock sequences.
+ * We deal with that by making maxMsgNum an atomic variable.  (The exact rule
+ * is that you need to use a barrier-providing accessor to read maxMsgNum if
+ * you are not holding SInvalWriteLock, and you need a barrier-providing
+ * accessor to write maxMsgNum unless you are holding both locks.)
  */
 
 
@@ -169,11 +159,9 @@ typedef struct SISeg
 	 * General state information
 	 */
 	int			minMsgNum;		/* oldest message still needed */
-	int			maxMsgNum;		/* next message number to be assigned */
+	pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */
 	int			nextThreshold;	/* # of messages to call SICleanupQueue */
 
-	slock_t		msgnumLock;		/* spinlock protecting maxMsgNum */
-
 	/*
 	 * Circular buffer holding shared-inval messages
 	 */
@@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg)
 {
 	int			i;
 
-	/* Clear message counters, init spinlock */
+	/* Clear message counters */
 	shmInvalBuffer->minMsgNum = 0;
-	shmInvalBuffer->maxMsgNum = 0;
+	pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0);
 	shmInvalBuffer->nextThreshold = CLEANUP_MIN;
-	SpinLockInit(&shmInvalBuffer->msgnumLock);
 
 	/* The buffer[] array is initially all unused, so we need not fill it */
 
@@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly)
 
 	/* mark myself active, with all extant messages already read */
 	stateP->procPid = MyProcPid;
-	stateP->nextMsgNum = segP->maxMsgNum;
+	stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum);
 	stateP->resetState = false;
 	stateP->signaled = false;
 	stateP->hasMessages = false;
@@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		 */
 		for (;;)
 		{
-			numMsgs = segP->maxMsgNum - segP->minMsgNum;
+			numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 			if (numMsgs + nthistime > MAXNUMMESSAGES ||
 				numMsgs >= segP->nextThreshold)
 				SICleanupQueue(true, nthistime);
@@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n)
 		/*
 		 * Insert new message(s) into proper slot of circular buffer
 		 */
-		max = segP->maxMsgNum;
+		max = pg_atomic_read_u32(&segP->maxMsgNum);
 		while (nthistime-- > 0)
 		{
 			segP->buffer[max % MAXNUMMESSAGES] = *data++;
 			max++;
 		}
 
-		/* Update current value of maxMsgNum using spinlock */
-		SpinLockAcquire(&segP->msgnumLock);
-		segP->maxMsgNum = max;
-		SpinLockRelease(&segP->msgnumLock);
+		/* Update current value of maxMsgNum using barrier */
+		pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max);
 
 		/*
 		 * Now that the maxMsgNum change is globally visible, we give everyone
@@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize)
 	 */
 	stateP->hasMessages = false;
 
-	/* Fetch current value of maxMsgNum using spinlock */
-	SpinLockAcquire(&segP->msgnumLock);
-	max = segP->maxMsgNum;
-	SpinLockRelease(&segP->msgnumLock);
+	/* Fetch current value of maxMsgNum using barrier */
+	max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum);
 
 	if (stateP->resetState)
 	{
@@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * backends here it is possible for them to keep sending messages without
 	 * a problem even when they are the only active backend.
 	 */
-	min = segP->maxMsgNum;
+	min = pg_atomic_read_u32(&segP->maxMsgNum);
 	minsig = min - SIG_THRESHOLD;
 	lowbound = min - MAXNUMMESSAGES + minFree;
 
@@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	if (min >= MSGNUMWRAPAROUND)
 	{
 		segP->minMsgNum -= MSGNUMWRAPAROUND;
-		segP->maxMsgNum -= MSGNUMWRAPAROUND;
+		pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND);
 		for (i = 0; i < segP->numProcs; i++)
 			segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND;
 	}
@@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree)
 	 * Determine how many messages are still in the queue, and set the
 	 * threshold at which we should repeat SICleanupQueue().
 	 */
-	numMsgs = segP->maxMsgNum - segP->minMsgNum;
+	numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum;
 	if (numMsgs < CLEANUP_MIN)
 		segP->nextThreshold = CLEANUP_MIN;
 	else
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch



^ permalink  raw  reply  [nested|flat] 67+ messages in thread

end of thread, other threads:[~2026-07-09 19:20 UTC | newest]

Thread overview: 67+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2026-03-11 14:20 [PATCH v45 4/8] Use BulkInsertState when copying data to the new heap. Antonin Houska <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox