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* [PATCH v5 6/7] Row pattern recognition patch (tests).
@ 2023-09-02 06:32 Tatsuo Ishii <[email protected]>
0 siblings, 0 replies; 203+ messages in thread
From: Tatsuo Ishii @ 2023-09-02 06:32 UTC (permalink / raw)
---
src/test/regress/expected/rpr.out | 463 +++++++++++++++++++++++++++++
src/test/regress/parallel_schedule | 2 +-
src/test/regress/sql/rpr.sql | 229 ++++++++++++++
3 files changed, 693 insertions(+), 1 deletion(-)
create mode 100644 src/test/regress/expected/rpr.out
create mode 100644 src/test/regress/sql/rpr.sql
diff --git a/src/test/regress/expected/rpr.out b/src/test/regress/expected/rpr.out
new file mode 100644
index 0000000000..340ccf242c
--- /dev/null
+++ b/src/test/regress/expected/rpr.out
@@ -0,0 +1,463 @@
+--
+-- Test for row pattern definition clause
+--
+CREATE TEMP TABLE stock (
+ company TEXT,
+ tdate DATE,
+ price INTEGER
+ );
+INSERT INTO stock VALUES ('company1', '2023-07-01', 100);
+INSERT INTO stock VALUES ('company1', '2023-07-02', 200);
+INSERT INTO stock VALUES ('company1', '2023-07-03', 150);
+INSERT INTO stock VALUES ('company1', '2023-07-04', 140);
+INSERT INTO stock VALUES ('company1', '2023-07-05', 150);
+INSERT INTO stock VALUES ('company1', '2023-07-06', 90);
+INSERT INTO stock VALUES ('company1', '2023-07-07', 110);
+INSERT INTO stock VALUES ('company1', '2023-07-08', 130);
+INSERT INTO stock VALUES ('company1', '2023-07-09', 120);
+INSERT INTO stock VALUES ('company1', '2023-07-10', 130);
+INSERT INTO stock VALUES ('company2', '2023-07-01', 50);
+INSERT INTO stock VALUES ('company2', '2023-07-02', 2000);
+INSERT INTO stock VALUES ('company2', '2023-07-03', 1500);
+INSERT INTO stock VALUES ('company2', '2023-07-04', 1400);
+INSERT INTO stock VALUES ('company2', '2023-07-05', 1500);
+INSERT INTO stock VALUES ('company2', '2023-07-06', 60);
+INSERT INTO stock VALUES ('company2', '2023-07-07', 1100);
+INSERT INTO stock VALUES ('company2', '2023-07-08', 1300);
+INSERT INTO stock VALUES ('company2', '2023-07-09', 1200);
+INSERT INTO stock VALUES ('company2', '2023-07-10', 1300);
+SELECT * FROM stock;
+ company | tdate | price
+----------+------------+-------
+ company1 | 07-01-2023 | 100
+ company1 | 07-02-2023 | 200
+ company1 | 07-03-2023 | 150
+ company1 | 07-04-2023 | 140
+ company1 | 07-05-2023 | 150
+ company1 | 07-06-2023 | 90
+ company1 | 07-07-2023 | 110
+ company1 | 07-08-2023 | 130
+ company1 | 07-09-2023 | 120
+ company1 | 07-10-2023 | 130
+ company2 | 07-01-2023 | 50
+ company2 | 07-02-2023 | 2000
+ company2 | 07-03-2023 | 1500
+ company2 | 07-04-2023 | 1400
+ company2 | 07-05-2023 | 1500
+ company2 | 07-06-2023 | 60
+ company2 | 07-07-2023 | 1100
+ company2 | 07-08-2023 | 1300
+ company2 | 07-09-2023 | 1200
+ company2 | 07-10-2023 | 1300
+(20 rows)
+
+-- basic test using PREV
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w,
+ nth_value(tdate, 2) OVER w AS nth_second
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (START UP+ DOWN+)
+ DEFINE
+ START AS TRUE,
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price)
+);
+ company | tdate | price | first_value | last_value | nth_second
+----------+------------+-------+-------------+------------+------------
+ company1 | 07-01-2023 | 100 | 100 | 140 | 07-02-2023
+ company1 | 07-02-2023 | 200 | | |
+ company1 | 07-03-2023 | 150 | | |
+ company1 | 07-04-2023 | 140 | | |
+ company1 | 07-05-2023 | 150 | | |
+ company1 | 07-06-2023 | 90 | 90 | 120 | 07-07-2023
+ company1 | 07-07-2023 | 110 | | |
+ company1 | 07-08-2023 | 130 | | |
+ company1 | 07-09-2023 | 120 | | |
+ company1 | 07-10-2023 | 130 | | |
+ company2 | 07-01-2023 | 50 | 50 | 1400 | 07-02-2023
+ company2 | 07-02-2023 | 2000 | | |
+ company2 | 07-03-2023 | 1500 | | |
+ company2 | 07-04-2023 | 1400 | | |
+ company2 | 07-05-2023 | 1500 | | |
+ company2 | 07-06-2023 | 60 | 60 | 1200 | 07-07-2023
+ company2 | 07-07-2023 | 1100 | | |
+ company2 | 07-08-2023 | 1300 | | |
+ company2 | 07-09-2023 | 1200 | | |
+ company2 | 07-10-2023 | 1300 | | |
+(20 rows)
+
+-- omit "START" in DEFINE but it is ok because "START AS TRUE" is
+-- implicitly defined. per spec.
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w,
+ nth_value(tdate, 2) OVER w AS nth_second
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (START UP+ DOWN+)
+ DEFINE
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price)
+);
+ company | tdate | price | first_value | last_value | nth_second
+----------+------------+-------+-------------+------------+------------
+ company1 | 07-01-2023 | 100 | 100 | 140 | 07-02-2023
+ company1 | 07-02-2023 | 200 | | |
+ company1 | 07-03-2023 | 150 | | |
+ company1 | 07-04-2023 | 140 | | |
+ company1 | 07-05-2023 | 150 | | |
+ company1 | 07-06-2023 | 90 | 90 | 120 | 07-07-2023
+ company1 | 07-07-2023 | 110 | | |
+ company1 | 07-08-2023 | 130 | | |
+ company1 | 07-09-2023 | 120 | | |
+ company1 | 07-10-2023 | 130 | | |
+ company2 | 07-01-2023 | 50 | 50 | 1400 | 07-02-2023
+ company2 | 07-02-2023 | 2000 | | |
+ company2 | 07-03-2023 | 1500 | | |
+ company2 | 07-04-2023 | 1400 | | |
+ company2 | 07-05-2023 | 1500 | | |
+ company2 | 07-06-2023 | 60 | 60 | 1200 | 07-07-2023
+ company2 | 07-07-2023 | 1100 | | |
+ company2 | 07-08-2023 | 1300 | | |
+ company2 | 07-09-2023 | 1200 | | |
+ company2 | 07-10-2023 | 1300 | | |
+(20 rows)
+
+-- the first row start with less than or equal to 100
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (LOWPRICE UP+ DOWN+)
+ DEFINE
+ LOWPRICE AS price <= 100,
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price)
+);
+ company | tdate | price | first_value | last_value
+----------+------------+-------+-------------+------------
+ company1 | 07-01-2023 | 100 | 100 | 140
+ company1 | 07-02-2023 | 200 | |
+ company1 | 07-03-2023 | 150 | |
+ company1 | 07-04-2023 | 140 | |
+ company1 | 07-05-2023 | 150 | |
+ company1 | 07-06-2023 | 90 | 90 | 120
+ company1 | 07-07-2023 | 110 | |
+ company1 | 07-08-2023 | 130 | |
+ company1 | 07-09-2023 | 120 | |
+ company1 | 07-10-2023 | 130 | |
+ company2 | 07-01-2023 | 50 | 50 | 1400
+ company2 | 07-02-2023 | 2000 | |
+ company2 | 07-03-2023 | 1500 | |
+ company2 | 07-04-2023 | 1400 | |
+ company2 | 07-05-2023 | 1500 | |
+ company2 | 07-06-2023 | 60 | 60 | 1200
+ company2 | 07-07-2023 | 1100 | |
+ company2 | 07-08-2023 | 1300 | |
+ company2 | 07-09-2023 | 1200 | |
+ company2 | 07-10-2023 | 1300 | |
+(20 rows)
+
+-- second row raises 120%
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (LOWPRICE UP+ DOWN+)
+ DEFINE
+ LOWPRICE AS price <= 100,
+ UP AS price > PREV(price) * 1.2,
+ DOWN AS price < PREV(price)
+);
+ company | tdate | price | first_value | last_value
+----------+------------+-------+-------------+------------
+ company1 | 07-01-2023 | 100 | 100 | 140
+ company1 | 07-02-2023 | 200 | |
+ company1 | 07-03-2023 | 150 | |
+ company1 | 07-04-2023 | 140 | |
+ company1 | 07-05-2023 | 150 | |
+ company1 | 07-06-2023 | 90 | |
+ company1 | 07-07-2023 | 110 | |
+ company1 | 07-08-2023 | 130 | |
+ company1 | 07-09-2023 | 120 | |
+ company1 | 07-10-2023 | 130 | |
+ company2 | 07-01-2023 | 50 | 50 | 1400
+ company2 | 07-02-2023 | 2000 | |
+ company2 | 07-03-2023 | 1500 | |
+ company2 | 07-04-2023 | 1400 | |
+ company2 | 07-05-2023 | 1500 | |
+ company2 | 07-06-2023 | 60 | |
+ company2 | 07-07-2023 | 1100 | |
+ company2 | 07-08-2023 | 1300 | |
+ company2 | 07-09-2023 | 1200 | |
+ company2 | 07-10-2023 | 1300 | |
+(20 rows)
+
+-- using NEXT
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (START UPDOWN)
+ DEFINE
+ START AS TRUE,
+ UPDOWN AS price > PREV(price) AND price > NEXT(price)
+);
+ company | tdate | price | first_value | last_value
+----------+------------+-------+-------------+------------
+ company1 | 07-01-2023 | 100 | 100 | 200
+ company1 | 07-02-2023 | 200 | |
+ company1 | 07-03-2023 | 150 | |
+ company1 | 07-04-2023 | 140 | 140 | 150
+ company1 | 07-05-2023 | 150 | |
+ company1 | 07-06-2023 | 90 | |
+ company1 | 07-07-2023 | 110 | 110 | 130
+ company1 | 07-08-2023 | 130 | |
+ company1 | 07-09-2023 | 120 | |
+ company1 | 07-10-2023 | 130 | |
+ company2 | 07-01-2023 | 50 | 50 | 2000
+ company2 | 07-02-2023 | 2000 | |
+ company2 | 07-03-2023 | 1500 | |
+ company2 | 07-04-2023 | 1400 | 1400 | 1500
+ company2 | 07-05-2023 | 1500 | |
+ company2 | 07-06-2023 | 60 | |
+ company2 | 07-07-2023 | 1100 | 1100 | 1300
+ company2 | 07-08-2023 | 1300 | |
+ company2 | 07-09-2023 | 1200 | |
+ company2 | 07-10-2023 | 1300 | |
+(20 rows)
+
+-- using AFTER MATCH SKIP TO NEXT ROW
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ INITIAL
+ PATTERN (START UPDOWN)
+ DEFINE
+ START AS TRUE,
+ UPDOWN AS price > PREV(price) AND price > NEXT(price)
+);
+ company | tdate | price | first_value | last_value
+----------+------------+-------+-------------+------------
+ company1 | 07-01-2023 | 100 | 100 | 200
+ company1 | 07-02-2023 | 200 | |
+ company1 | 07-03-2023 | 150 | |
+ company1 | 07-04-2023 | 140 | 140 | 150
+ company1 | 07-05-2023 | 150 | |
+ company1 | 07-06-2023 | 90 | |
+ company1 | 07-07-2023 | 110 | 110 | 130
+ company1 | 07-08-2023 | 130 | |
+ company1 | 07-09-2023 | 120 | |
+ company1 | 07-10-2023 | 130 | |
+ company2 | 07-01-2023 | 50 | 50 | 2000
+ company2 | 07-02-2023 | 2000 | |
+ company2 | 07-03-2023 | 1500 | |
+ company2 | 07-04-2023 | 1400 | 1400 | 1500
+ company2 | 07-05-2023 | 1500 | |
+ company2 | 07-06-2023 | 60 | |
+ company2 | 07-07-2023 | 1100 | 1100 | 1300
+ company2 | 07-08-2023 | 1300 | |
+ company2 | 07-09-2023 | 1200 | |
+ company2 | 07-10-2023 | 1300 | |
+(20 rows)
+
+-- match everything
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ORDER BY tdate
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP PAST LAST ROW
+ INITIAL
+ PATTERN (A+)
+ DEFINE
+ A AS TRUE
+);
+ company | tdate | price | first_value | last_value
+----------+------------+-------+-------------+------------
+ company1 | 07-01-2023 | 100 | 100 | 130
+ company1 | 07-02-2023 | 200 | |
+ company1 | 07-03-2023 | 150 | |
+ company1 | 07-04-2023 | 140 | |
+ company1 | 07-05-2023 | 150 | |
+ company1 | 07-06-2023 | 90 | |
+ company1 | 07-07-2023 | 110 | |
+ company1 | 07-08-2023 | 130 | |
+ company1 | 07-09-2023 | 120 | |
+ company1 | 07-10-2023 | 130 | |
+ company2 | 07-01-2023 | 50 | 50 | 1300
+ company2 | 07-02-2023 | 2000 | |
+ company2 | 07-03-2023 | 1500 | |
+ company2 | 07-04-2023 | 1400 | |
+ company2 | 07-05-2023 | 1500 | |
+ company2 | 07-06-2023 | 60 | |
+ company2 | 07-07-2023 | 1100 | |
+ company2 | 07-08-2023 | 1300 | |
+ company2 | 07-09-2023 | 1200 | |
+ company2 | 07-10-2023 | 1300 | |
+(20 rows)
+
+-- backtracking with reclassification of rows
+-- using AFTER MATCH SKIP PAST LAST ROW
+SELECT company, tdate, price, first_value(tdate) OVER w, last_value(tdate) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ORDER BY tdate
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP PAST LAST ROW
+ INITIAL
+ PATTERN (A+ B+)
+ DEFINE
+ A AS price > 100,
+ B AS price > 100
+);
+ company | tdate | price | first_value | last_value
+----------+------------+-------+-------------+------------
+ company1 | 07-01-2023 | 100 | |
+ company1 | 07-02-2023 | 200 | 07-02-2023 | 07-05-2023
+ company1 | 07-03-2023 | 150 | |
+ company1 | 07-04-2023 | 140 | |
+ company1 | 07-05-2023 | 150 | |
+ company1 | 07-06-2023 | 90 | |
+ company1 | 07-07-2023 | 110 | 07-07-2023 | 07-10-2023
+ company1 | 07-08-2023 | 130 | |
+ company1 | 07-09-2023 | 120 | |
+ company1 | 07-10-2023 | 130 | |
+ company2 | 07-01-2023 | 50 | |
+ company2 | 07-02-2023 | 2000 | 07-02-2023 | 07-05-2023
+ company2 | 07-03-2023 | 1500 | |
+ company2 | 07-04-2023 | 1400 | |
+ company2 | 07-05-2023 | 1500 | |
+ company2 | 07-06-2023 | 60 | |
+ company2 | 07-07-2023 | 1100 | 07-07-2023 | 07-10-2023
+ company2 | 07-08-2023 | 1300 | |
+ company2 | 07-09-2023 | 1200 | |
+ company2 | 07-10-2023 | 1300 | |
+(20 rows)
+
+-- backtracking with reclassification of rows
+-- using AFTER MATCH SKIP TO NEXT ROW
+SELECT company, tdate, price, first_value(tdate) OVER w, last_value(tdate) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ORDER BY tdate
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ INITIAL
+ PATTERN (A+ B+)
+ DEFINE
+ A AS price > 100,
+ B AS price > 100
+);
+ company | tdate | price | first_value | last_value
+----------+------------+-------+-------------+------------
+ company1 | 07-01-2023 | 100 | |
+ company1 | 07-02-2023 | 200 | 07-02-2023 | 07-05-2023
+ company1 | 07-03-2023 | 150 | 07-03-2023 | 07-05-2023
+ company1 | 07-04-2023 | 140 | 07-04-2023 | 07-05-2023
+ company1 | 07-05-2023 | 150 | |
+ company1 | 07-06-2023 | 90 | |
+ company1 | 07-07-2023 | 110 | 07-07-2023 | 07-10-2023
+ company1 | 07-08-2023 | 130 | 07-08-2023 | 07-10-2023
+ company1 | 07-09-2023 | 120 | 07-09-2023 | 07-10-2023
+ company1 | 07-10-2023 | 130 | |
+ company2 | 07-01-2023 | 50 | |
+ company2 | 07-02-2023 | 2000 | 07-02-2023 | 07-05-2023
+ company2 | 07-03-2023 | 1500 | 07-03-2023 | 07-05-2023
+ company2 | 07-04-2023 | 1400 | 07-04-2023 | 07-05-2023
+ company2 | 07-05-2023 | 1500 | |
+ company2 | 07-06-2023 | 60 | |
+ company2 | 07-07-2023 | 1100 | 07-07-2023 | 07-10-2023
+ company2 | 07-08-2023 | 1300 | 07-08-2023 | 07-10-2023
+ company2 | 07-09-2023 | 1200 | 07-09-2023 | 07-10-2023
+ company2 | 07-10-2023 | 1300 | |
+(20 rows)
+
+--
+-- Error cases
+--
+-- row pattern definition variable name must not appear more than once
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ ORDER BY tdate
+ INITIAL
+ PATTERN (START UP+ DOWN+)
+ DEFINE
+ START AS TRUE,
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price),
+ UP AS price > PREV(price)
+);
+ERROR: syntax error at or near "ORDER"
+LINE 6: ORDER BY tdate
+ ^
+-- pattern variable name must appear in DEFINE
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ORDER BY tdate
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (START UP+ DOWN+ END)
+ DEFINE
+ START AS TRUE,
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price)
+);
+ERROR: syntax error at or near "END"
+LINE 8: PATTERN (START UP+ DOWN+ END)
+ ^
+-- FRAME must start at current row when row patttern recognition is used
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ORDER BY tdate
+ ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (START UP+ DOWN+)
+ DEFINE
+ START AS TRUE,
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price)
+);
+ERROR: FRAME must start at current row when row patttern recognition is used
+-- SEEK is not supported
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ORDER BY tdate
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ SEEK
+ PATTERN (START UP+ DOWN+)
+ DEFINE
+ START AS TRUE,
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price)
+);
+ERROR: SEEK is not supported
+LINE 8: SEEK
+ ^
+HINT: Use INITIAL.
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 4df9d8503b..896531002b 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -98,7 +98,7 @@ test: publication subscription
# Another group of parallel tests
# select_views depends on create_view
# ----------
-test: select_views portals_p2 foreign_key cluster dependency guc bitmapops combocid tsearch tsdicts foreign_data window xmlmap functional_deps advisory_lock indirect_toast equivclass
+test: select_views portals_p2 foreign_key cluster dependency guc bitmapops combocid tsearch tsdicts foreign_data window xmlmap functional_deps advisory_lock indirect_toast equivclass rpr
# ----------
# Another group of parallel tests (JSON related)
diff --git a/src/test/regress/sql/rpr.sql b/src/test/regress/sql/rpr.sql
new file mode 100644
index 0000000000..c4f704cdc4
--- /dev/null
+++ b/src/test/regress/sql/rpr.sql
@@ -0,0 +1,229 @@
+--
+-- Test for row pattern definition clause
+--
+
+CREATE TEMP TABLE stock (
+ company TEXT,
+ tdate DATE,
+ price INTEGER
+ );
+INSERT INTO stock VALUES ('company1', '2023-07-01', 100);
+INSERT INTO stock VALUES ('company1', '2023-07-02', 200);
+INSERT INTO stock VALUES ('company1', '2023-07-03', 150);
+INSERT INTO stock VALUES ('company1', '2023-07-04', 140);
+INSERT INTO stock VALUES ('company1', '2023-07-05', 150);
+INSERT INTO stock VALUES ('company1', '2023-07-06', 90);
+INSERT INTO stock VALUES ('company1', '2023-07-07', 110);
+INSERT INTO stock VALUES ('company1', '2023-07-08', 130);
+INSERT INTO stock VALUES ('company1', '2023-07-09', 120);
+INSERT INTO stock VALUES ('company1', '2023-07-10', 130);
+INSERT INTO stock VALUES ('company2', '2023-07-01', 50);
+INSERT INTO stock VALUES ('company2', '2023-07-02', 2000);
+INSERT INTO stock VALUES ('company2', '2023-07-03', 1500);
+INSERT INTO stock VALUES ('company2', '2023-07-04', 1400);
+INSERT INTO stock VALUES ('company2', '2023-07-05', 1500);
+INSERT INTO stock VALUES ('company2', '2023-07-06', 60);
+INSERT INTO stock VALUES ('company2', '2023-07-07', 1100);
+INSERT INTO stock VALUES ('company2', '2023-07-08', 1300);
+INSERT INTO stock VALUES ('company2', '2023-07-09', 1200);
+INSERT INTO stock VALUES ('company2', '2023-07-10', 1300);
+
+SELECT * FROM stock;
+
+-- basic test using PREV
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w,
+ nth_value(tdate, 2) OVER w AS nth_second
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (START UP+ DOWN+)
+ DEFINE
+ START AS TRUE,
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price)
+);
+
+-- omit "START" in DEFINE but it is ok because "START AS TRUE" is
+-- implicitly defined. per spec.
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w,
+ nth_value(tdate, 2) OVER w AS nth_second
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (START UP+ DOWN+)
+ DEFINE
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price)
+);
+
+-- the first row start with less than or equal to 100
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (LOWPRICE UP+ DOWN+)
+ DEFINE
+ LOWPRICE AS price <= 100,
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price)
+);
+
+-- second row raises 120%
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (LOWPRICE UP+ DOWN+)
+ DEFINE
+ LOWPRICE AS price <= 100,
+ UP AS price > PREV(price) * 1.2,
+ DOWN AS price < PREV(price)
+);
+
+-- using NEXT
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (START UPDOWN)
+ DEFINE
+ START AS TRUE,
+ UPDOWN AS price > PREV(price) AND price > NEXT(price)
+);
+
+-- using AFTER MATCH SKIP TO NEXT ROW
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ INITIAL
+ PATTERN (START UPDOWN)
+ DEFINE
+ START AS TRUE,
+ UPDOWN AS price > PREV(price) AND price > NEXT(price)
+);
+
+-- match everything
+
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ORDER BY tdate
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP PAST LAST ROW
+ INITIAL
+ PATTERN (A+)
+ DEFINE
+ A AS TRUE
+);
+
+-- backtracking with reclassification of rows
+-- using AFTER MATCH SKIP PAST LAST ROW
+SELECT company, tdate, price, first_value(tdate) OVER w, last_value(tdate) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ORDER BY tdate
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP PAST LAST ROW
+ INITIAL
+ PATTERN (A+ B+)
+ DEFINE
+ A AS price > 100,
+ B AS price > 100
+);
+
+-- backtracking with reclassification of rows
+-- using AFTER MATCH SKIP TO NEXT ROW
+SELECT company, tdate, price, first_value(tdate) OVER w, last_value(tdate) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ORDER BY tdate
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ INITIAL
+ PATTERN (A+ B+)
+ DEFINE
+ A AS price > 100,
+ B AS price > 100
+);
+
+--
+-- Error cases
+--
+
+-- row pattern definition variable name must not appear more than once
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ ORDER BY tdate
+ INITIAL
+ PATTERN (START UP+ DOWN+)
+ DEFINE
+ START AS TRUE,
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price),
+ UP AS price > PREV(price)
+);
+
+-- pattern variable name must appear in DEFINE
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ORDER BY tdate
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (START UP+ DOWN+ END)
+ DEFINE
+ START AS TRUE,
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price)
+);
+
+-- FRAME must start at current row when row patttern recognition is used
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ORDER BY tdate
+ ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
+ INITIAL
+ PATTERN (START UP+ DOWN+)
+ DEFINE
+ START AS TRUE,
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price)
+);
+
+-- SEEK is not supported
+SELECT company, tdate, price, first_value(price) OVER w, last_value(price) OVER w
+ FROM stock
+ WINDOW w AS (
+ PARTITION BY company
+ ORDER BY tdate
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ SEEK
+ PATTERN (START UP+ DOWN+)
+ DEFINE
+ START AS TRUE,
+ UP AS price > PREV(price),
+ DOWN AS price < PREV(price)
+);
--
2.25.1
----Next_Part(Sat_Sep__2_15_52_35_2023_273)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
filename="v5-0007-Allow-to-print-raw-parse-tree.patch"
^ permalink raw reply [nested|flat] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ 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; 203+ 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] 203+ messages in thread
end of thread, other threads:[~2026-07-09 20:21 UTC | newest]
Thread overview: 203+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2023-09-02 06:32 [PATCH v5 6/7] Row pattern recognition patch (tests). Tatsuo Ishii <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
2026-07-09 20:21 [PATCH v1 7/8] convert ParallelBlockTableScanDescData->phs_{start,num}block to atomics Nathan Bossart <[email protected]>
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