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[PATCH v20 4/8] Row pattern recognition patch (planner).
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* [PATCH v20 4/8] Row pattern recognition patch (planner).
@ 2024-05-24 02:26 Tatsuo Ishii <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Tatsuo Ishii @ 2024-05-24 02:26 UTC (permalink / raw)

---
 src/backend/optimizer/plan/createplan.c   | 24 +++++++++++++++-----
 src/backend/optimizer/plan/planner.c      |  3 +++
 src/backend/optimizer/plan/setrefs.c      | 27 ++++++++++++++++++++++-
 src/backend/optimizer/prep/prepjointree.c |  9 ++++++++
 src/include/nodes/plannodes.h             | 19 ++++++++++++++++
 5 files changed, 76 insertions(+), 6 deletions(-)

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 6b64c4a362..ef2101e216 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -287,9 +287,11 @@ static WindowAgg *make_windowagg(List *tlist, Index winref,
 								 int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 								 int frameOptions, Node *startOffset, Node *endOffset,
 								 Oid startInRangeFunc, Oid endInRangeFunc,
-								 Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
-								 List *runCondition, List *qual, bool topWindow,
-								 Plan *lefttree);
+								 Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst, List *runCondition,
+								 RPSkipTo rpSkipTo, List *patternVariable, List *patternRegexp,
+								 List *defineClause,
+								 List *defineInitial,
+								 List *qual, bool topWindow, Plan *lefttree);
 static Group *make_group(List *tlist, List *qual, int numGroupCols,
 						 AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 						 Plan *lefttree);
@@ -2700,6 +2702,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 						  wc->inRangeAsc,
 						  wc->inRangeNullsFirst,
 						  best_path->runCondition,
+						  wc->rpSkipTo,
+						  wc->patternVariable,
+						  wc->patternRegexp,
+						  wc->defineClause,
+						  wc->defineInitial,
 						  best_path->qual,
 						  best_path->topwindow,
 						  subplan);
@@ -6629,8 +6636,10 @@ make_windowagg(List *tlist, Index winref,
 			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
-			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
-			   List *runCondition, List *qual, bool topWindow, Plan *lefttree)
+			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst, List *runCondition,
+			   RPSkipTo rpSkipTo, List *patternVariable, List *patternRegexp, List *defineClause,
+			   List *defineInitial,
+			   List *qual, bool topWindow, Plan *lefttree)
 {
 	WindowAgg  *node = makeNode(WindowAgg);
 	Plan	   *plan = &node->plan;
@@ -6656,6 +6665,11 @@ make_windowagg(List *tlist, Index winref,
 	node->inRangeAsc = inRangeAsc;
 	node->inRangeNullsFirst = inRangeNullsFirst;
 	node->topWindow = topWindow;
+	node->rpSkipTo = rpSkipTo,
+		node->patternVariable = patternVariable;
+	node->patternRegexp = patternRegexp;
+	node->defineClause = defineClause;
+	node->defineInitial = defineInitial;
 
 	plan->targetlist = tlist;
 	plan->lefttree = lefttree;
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 032818423f..a5d17e3fda 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -870,6 +870,9 @@ subquery_planner(PlannerGlobal *glob, Query *parse, PlannerInfo *parent_root,
 												EXPRKIND_LIMIT);
 		wc->endOffset = preprocess_expression(root, wc->endOffset,
 											  EXPRKIND_LIMIT);
+		wc->defineClause = (List *) preprocess_expression(root,
+														  (Node *) wc->defineClause,
+														  EXPRKIND_TARGET);
 	}
 
 	parse->limitOffset = preprocess_expression(root, parse->limitOffset,
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 37abcb4701..cd0e7c57d8 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -210,7 +210,6 @@ static List *set_windowagg_runcondition_references(PlannerInfo *root,
 												   List *runcondition,
 												   Plan *plan);
 
-
 /*****************************************************************************
  *
  *		SUBPLAN REFERENCES
@@ -2471,6 +2470,32 @@ set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset)
 					   NRM_EQUAL,
 					   NUM_EXEC_QUAL(plan));
 
+	/*
+	 * Modifies an expression tree in each DEFINE clause so that all Var
+	 * nodes's varno refers to OUTER_VAR.
+	 */
+	if (IsA(plan, WindowAgg))
+	{
+		WindowAgg  *wplan = (WindowAgg *) plan;
+
+		if (wplan->defineClause != NIL)
+		{
+			foreach(l, wplan->defineClause)
+			{
+				TargetEntry *tle = (TargetEntry *) lfirst(l);
+
+				tle->expr = (Expr *)
+					fix_upper_expr(root,
+								   (Node *) tle->expr,
+								   subplan_itlist,
+								   OUTER_VAR,
+								   rtoffset,
+								   NRM_EQUAL,
+								   NUM_EXEC_QUAL(plan));
+			}
+		}
+	}
+
 	pfree(subplan_itlist);
 }
 
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 5482ab85a7..f54db3f044 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -2175,6 +2175,15 @@ perform_pullup_replace_vars(PlannerInfo *root,
 	parse->returningList = (List *)
 		pullup_replace_vars((Node *) parse->returningList, rvcontext);
 
+	foreach(lc, parse->windowClause)
+	{
+		WindowClause *wc = lfirst_node(WindowClause, lc);
+
+		if (wc->defineClause != NIL)
+			wc->defineClause = (List *)
+				pullup_replace_vars((Node *) wc->defineClause, rvcontext);
+	}
+
 	if (parse->onConflict)
 	{
 		parse->onConflict->onConflictSet = (List *)
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 1aeeaec95e..5b8d8a6dac 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -20,6 +20,7 @@
 #include "lib/stringinfo.h"
 #include "nodes/bitmapset.h"
 #include "nodes/lockoptions.h"
+#include "nodes/parsenodes.h"
 #include "nodes/primnodes.h"
 
 
@@ -1098,6 +1099,24 @@ typedef struct WindowAgg
 	/* nulls sort first for in_range tests? */
 	bool		inRangeNullsFirst;
 
+	/* Row Pattern Recognition AFTER MACH SKIP clause */
+	RPSkipTo	rpSkipTo;		/* Row Pattern Skip To type */
+
+	/* Row Pattern PATTERN variable name (list of String) */
+	List	   *patternVariable;
+
+	/*
+	 * Row Pattern RPATTERN regular expression quantifier ('+' or ''. list of
+	 * String)
+	 */
+	List	   *patternRegexp;
+
+	/* Row Pattern DEFINE clause (list of TargetEntry) */
+	List	   *defineClause;
+
+	/* Row Pattern DEFINE variable initial names (list of String) */
+	List	   *defineInitial;
+
 	/*
 	 * false for all apart from the WindowAgg that's closest to the root of
 	 * the plan
-- 
2.25.1


----Next_Part(Fri_May_24_11_39_19_2024_763)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v20-0005-Row-pattern-recognition-patch-executor.patch"



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


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Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread

* [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics
@ 2026-07-09 20:21 Nathan Bossart <[email protected]>
  0 siblings, 0 replies; 79+ messages in thread

From: Nathan Bossart @ 2026-07-09 20:21 UTC (permalink / raw)

---
 src/backend/access/heap/heapam_handler.c |  2 +-
 src/backend/access/table/tableam.c       | 59 +++++++++++-------------
 src/include/access/relscan.h             |  8 ++--
 3 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index bf87430cf01..0f24a132564 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -1965,7 +1965,7 @@ heapam_scan_get_blocks_done(HeapScanDesc hscan)
 	if (hscan->rs_base.rs_parallel != NULL)
 	{
 		bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel;
-		startblock = bpscan->phs_startblock;
+		startblock = pg_atomic_read_u32(&bpscan->phs_startblock);
 	}
 	else
 		startblock = hscan->rs_startblock;
diff --git a/src/backend/access/table/tableam.c b/src/backend/access/table/tableam.c
index 68ff0966f1c..f2038ea9205 100644
--- a/src/backend/access/table/tableam.c
+++ b/src/backend/access/table/tableam.c
@@ -421,9 +421,8 @@ table_block_parallelscan_initialize(Relation rel, ParallelTableScanDesc pscan)
 	bpscan->base.phs_syncscan = synchronize_seqscans &&
 		!RelationUsesLocalBuffers(rel) &&
 		bpscan->phs_nblocks > NBuffers / 4;
-	SpinLockInit(&bpscan->phs_mutex);
-	bpscan->phs_startblock = InvalidBlockNumber;
-	bpscan->phs_numblock = InvalidBlockNumber;
+	pg_atomic_init_u32(&bpscan->phs_startblock, InvalidBlockNumber);
+	pg_atomic_init_u32(&bpscan->phs_numblock, InvalidBlockNumber);
 	pg_atomic_init_u64(&bpscan->phs_nallocated, 0);
 
 	return sizeof(ParallelBlockTableScanDescData);
@@ -459,25 +458,22 @@ table_block_parallelscan_startblock_init(Relation rel,
 	StaticAssertDecl(MaxBlockNumber <= 0xFFFFFFFE,
 					 "pg_nextpower2_32 may be too small for non-standard BlockNumber width");
 
-	BlockNumber sync_startpage = InvalidBlockNumber;
 	BlockNumber scan_nblocks;
 
 	/* Reset the state we use for controlling allocation size. */
 	memset(pbscanwork, 0, sizeof(*pbscanwork));
 
-retry:
-	/* Grab the spinlock. */
-	SpinLockAcquire(&pbscan->phs_mutex);
-
 	/*
 	 * When the caller specified a limit on the number of blocks to scan, set
 	 * that in the ParallelBlockTableScanDesc, if it's not been done by
 	 * another worker already.
 	 */
-	if (numblocks != InvalidBlockNumber &&
-		pbscan->phs_numblock == InvalidBlockNumber)
+	if (numblocks != InvalidBlockNumber)
 	{
-		pbscan->phs_numblock = numblocks;
+		uint32		expected = InvalidBlockNumber;
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_numblock, &expected,
+									   numblocks);
 	}
 
 	/*
@@ -485,36 +481,35 @@ retry:
 	 * so now.  If a startblock was specified, start there, otherwise if this
 	 * is not a synchronized scan, we just start at block 0, but if it is a
 	 * synchronized scan, we must get the starting position from the
-	 * synchronized scan machinery.  We can't hold the spinlock while doing
-	 * that, though, so release the spinlock, get the information we need, and
-	 * retry.  If nobody else has initialized the scan in the meantime, we'll
-	 * fill in the value we fetched on the second time through.
+	 * synchronized scan machinery.
+	 *
+	 * If another worker initializes phs_startblock concurrently, just use
+	 * their value.
 	 */
-	if (pbscan->phs_startblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_startblock) == InvalidBlockNumber)
 	{
+		BlockNumber newstartblock;
+		uint32		expected = InvalidBlockNumber;
+
 		if (startblock != InvalidBlockNumber)
-			pbscan->phs_startblock = startblock;
+			newstartblock = startblock;
 		else if (!pbscan->base.phs_syncscan)
-			pbscan->phs_startblock = 0;
-		else if (sync_startpage != InvalidBlockNumber)
-			pbscan->phs_startblock = sync_startpage;
+			newstartblock = 0;
 		else
-		{
-			SpinLockRelease(&pbscan->phs_mutex);
-			sync_startpage = ss_get_location(rel, pbscan->phs_nblocks);
-			goto retry;
-		}
+			newstartblock = ss_get_location(rel, pbscan->phs_nblocks);
+
+		pg_atomic_compare_exchange_u32(&pbscan->phs_startblock, &expected,
+									   newstartblock);
 	}
-	SpinLockRelease(&pbscan->phs_mutex);
 
 	/*
 	 * Figure out how many blocks we're going to scan; either all of them, or
 	 * just phs_numblock's worth, if a limit has been imposed.
 	 */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * We determine the chunk size based on scan_nblocks.  First we split
@@ -595,10 +590,10 @@ table_block_parallelscan_nextpage(Relation rel,
 	 */
 
 	/* First, figure out how many blocks we're planning on scanning */
-	if (pbscan->phs_numblock == InvalidBlockNumber)
+	if (pg_atomic_read_u32(&pbscan->phs_numblock) == InvalidBlockNumber)
 		scan_nblocks = pbscan->phs_nblocks;
 	else
-		scan_nblocks = pbscan->phs_numblock;
+		scan_nblocks = pg_atomic_read_u32(&pbscan->phs_numblock);
 
 	/*
 	 * Now check if we have any remaining blocks in a previous chunk for this
@@ -644,7 +639,7 @@ table_block_parallelscan_nextpage(Relation rel,
 	if (nallocated >= scan_nblocks)
 		page = InvalidBlockNumber;	/* all blocks have been allocated */
 	else
-		page = (nallocated + pbscan->phs_startblock) % pbscan->phs_nblocks;
+		page = (nallocated + pg_atomic_read_u32(&pbscan->phs_startblock)) % pbscan->phs_nblocks;
 
 	/*
 	 * Report scan location.  Normally, we report the current page number.
@@ -658,7 +653,7 @@ table_block_parallelscan_nextpage(Relation rel,
 		if (page != InvalidBlockNumber)
 			ss_report_location(rel, page);
 		else if (nallocated == pbscan->phs_nblocks)
-			ss_report_location(rel, pbscan->phs_startblock);
+			ss_report_location(rel, pg_atomic_read_u32(&pbscan->phs_startblock));
 	}
 
 	return page;
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index 2ea06a67a63..2305d0159f3 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -19,7 +19,6 @@
 #include "nodes/tidbitmap.h"
 #include "port/atomics.h"
 #include "storage/relfilelocator.h"
-#include "storage/spin.h"
 #include "utils/relcache.h"
 
 
@@ -99,10 +98,9 @@ typedef struct ParallelBlockTableScanDescData
 	ParallelTableScanDescData base;
 
 	BlockNumber phs_nblocks;	/* # blocks in relation at start of scan */
-	slock_t		phs_mutex;		/* mutual exclusion for setting startblock */
-	BlockNumber phs_startblock; /* starting block number */
-	BlockNumber phs_numblock;	/* # blocks to scan, or InvalidBlockNumber if
-								 * no limit */
+	pg_atomic_uint32 phs_startblock;	/* starting block number */
+	pg_atomic_uint32 phs_numblock;	/* # blocks to scan, or InvalidBlockNumber
+									 * if no limit */
 	pg_atomic_uint64 phs_nallocated;	/* number of blocks allocated to
 										 * workers so far. */
 }			ParallelBlockTableScanDescData;
-- 
2.50.1 (Apple Git-155)


--Ot5x3ffkWEuxilWO
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
	filename=v1-0008-convert-FastPathStrongRelationLocks-to-atomics.patch



^ permalink  raw  reply  [nested|flat] 79+ messages in thread