Hi,
On Wed, Jul 23, 2025 at 12:23:37PM +0900, Michael Paquier wrote:
> On Tue, Jul 22, 2025 at 02:25:13PM -0500, Nathan Bossart wrote:
> > I stared at this patch some more and came up with the attached. The
> > biggest change is that I've moved the list of built-in LWLock tranches to
> > the existing lwlocklist.h file. That simplifies the patch and centralizes
> > these lists. This is arguably a bit too much preprocessor magic, though.
Yeah, but OTOH we avoid the addition of a new file and we avoid changing some
meson and make files. Also the distinction is still clear as we are using a new
macro name. So that's fine by me.
> > Thoughts?
I noticed that you removed the LWTRANCHE_ prefix in lwlocklist.h, while I agree
that's not needed, that could be misleading for people that grep for things like
"LWTRANCHE_XACT_BUFFER" for example. I don't think that's a big deal though.
Also, I think we don't need to read lwlocklist.h twice in
generate-lwlocknames.pl.
PFA v4 where the only change compared to v3 is that it reads lwlocklist.h once
in generate-lwlocknames.pl.
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
>From 56bf036718866eccc04736a36da47968e7b68d9e Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nat...@postgresql.org>
Date: Tue, 22 Jul 2025 14:13:11 -0500
Subject: [PATCH v4] Cross check lists of built-in LWLock tranches.
---
.../storage/lmgr/generate-lwlocknames.pl | 103 +++++++++++++-----
src/backend/storage/lmgr/lwlock.c | 48 +-------
.../utils/activity/wait_event_names.txt | 10 +-
src/include/storage/lwlock.h | 56 +++-------
src/include/storage/lwlocklist.h | 57 +++++++++-
5 files changed, 156 insertions(+), 118 deletions(-)
diff --git a/src/backend/storage/lmgr/generate-lwlocknames.pl b/src/backend/storage/lmgr/generate-lwlocknames.pl
index c7a6720440d..6bd6175f2e6 100644
--- a/src/backend/storage/lmgr/generate-lwlocknames.pl
+++ b/src/backend/storage/lmgr/generate-lwlocknames.pl
@@ -27,18 +27,24 @@ print $h "/* there is deliberately not an #ifndef LWLOCKNAMES_H here */\n\n";
#
-# First, record the predefined LWLocks listed in wait_event_names.txt. We'll
-# cross-check those with the ones in lwlocklist.h.
+# First, record the predefined LWLocks and built-in tranches listed in
+# wait_event_names.txt. We'll cross-check those with the ones in lwlocklist.h.
#
+my @wait_event_tranches;
my @wait_event_lwlocks;
my $record_lwlocks = 0;
+my $in_tranches = 0;
while (<$wait_event_names>)
{
chomp;
# Check for end marker.
- last if /^# END OF PREDEFINED LWLOCKS/;
+ if (/^# END OF PREDEFINED LWLOCKS/)
+ {
+ $in_tranches = 1;
+ next;
+ }
# Skip comments and empty lines.
next if /^#/;
@@ -54,13 +60,27 @@ while (<$wait_event_names>)
# Go to the next line if we are not yet recording LWLocks.
next if not $record_lwlocks;
+ # Stop recording if we reach another section.
+ last if /^Section:/;
+
# Record the LWLock.
(my $waiteventname, my $waitevendocsentence) = split(/\t/, $_);
- push(@wait_event_lwlocks, $waiteventname);
+
+ if ($in_tranches)
+ {
+ push(@wait_event_tranches, $waiteventname);
+ }
+ else
+ {
+ push(@wait_event_lwlocks, $waiteventname);
+ }
}
+# Cross-check lists of predefined LWLocks and built-in LWLock tranches with their
+# wait events.
my $in_comment = 0;
-my $i = 0;
+my $lwlock_count = 0;
+my $tranche_count = 0;
while (<$lwlocklist>)
{
chomp;
@@ -81,38 +101,69 @@ while (<$lwlocklist>)
next;
}
- die "unable to parse lwlocklist.h line \"$_\""
- unless /^PG_LWLOCK\((\d+),\s+(\w+)\)$/;
+ # Parse PG_LWLOCK entries to cross-check the predefined LWLocks
+ if (/^PG_LWLOCK\((\d+),\s+(\w+)\)$/)
+ {
+ my ($lockidx, $lockname) = ($1, $2);
- (my $lockidx, my $lockname) = ($1, $2);
+ die "lwlocklist.h not in order" if $lockidx < $lastlockidx;
+ die "lwlocklist.h has duplicates" if $lockidx == $lastlockidx;
- die "lwlocklist.h not in order" if $lockidx < $lastlockidx;
- die "lwlocklist.h has duplicates" if $lockidx == $lastlockidx;
+ die "$lockname defined in lwlocklist.h but missing from "
+ . "wait_event_names.txt"
+ if $lwlock_count >= scalar @wait_event_lwlocks;
+ die "lists of predefined LWLocks do not match (first mismatch at "
+ . "$wait_event_lwlocks[$lwlock_count] in wait_event_names.txt and $lockname in "
+ . "lwlocklist.h)"
+ if $wait_event_lwlocks[$lwlock_count] ne $lockname;
- die "$lockname defined in lwlocklist.h but missing from "
- . "wait_event_names.txt"
- if $i >= scalar @wait_event_lwlocks;
- die "lists of predefined LWLocks do not match (first mismatch at "
- . "$wait_event_lwlocks[$i] in wait_event_names.txt and $lockname in "
- . "lwlocklist.h)"
- if $wait_event_lwlocks[$i] ne $lockname;
- $i++;
+ $lwlock_count++;
- while ($lastlockidx < $lockidx - 1)
+ while ($lastlockidx < $lockidx - 1)
+ {
+ ++$lastlockidx;
+ }
+ $lastlockidx = $lockidx;
+
+ # Add a "Lock" suffix to each lock name, as the C code depends on that
+ printf $h "#define %-32s (&MainLWLockArray[$lockidx].lock)\n",
+ $lockname . "Lock";
+
+ next;
+ }
+
+ # Parse PG_LWLOCKTRANCHE\ entries to cross-check the built-in LWLock tranches
+ if (/^PG_LWLOCKTRANCHE\((\w+),\s+(\w+)\)$/)
{
- ++$lastlockidx;
+ my ($tranche_id, $tranche_name) = ($1, $2);
+
+ die "$tranche_name defined in lwlocklist.h but missing from "
+ . "wait_event_names.txt"
+ if $tranche_count >= scalar @wait_event_tranches;
+ die
+ "lists of built-in LWLock tranches do not match (first mismatch at "
+ . "$wait_event_tranches[$tranche_count] in wait_event_names.txt and $tranche_name "
+ . "in lwlocklist.h)"
+ if $wait_event_tranches[$tranche_count] ne $tranche_name;
+
+ $tranche_count++;
+ next;
}
- $lastlockidx = $lockidx;
- # Add a "Lock" suffix to each lock name, as the C code depends on that
- printf $h "#define %-32s (&MainLWLockArray[$lockidx].lock)\n",
- $lockname . "Lock";
+ # If we get here, the line couldn't be parsed
+ die "unable to parse lwlocklist.h line \"$_\"";
}
+# Ensure we found all expected entries
+die
+ "$wait_event_lwlocks[$lwlock_count] defined in wait_event_names.txt but missing from "
+ . "lwlocklist.h"
+ if $lwlock_count < scalar @wait_event_lwlocks;
+
die
- "$wait_event_lwlocks[$i] defined in wait_event_names.txt but missing from "
+ "$wait_event_tranches[$tranche_count] defined in wait_event_names.txt but missing from "
. "lwlocklist.h"
- if $i < scalar @wait_event_lwlocks;
+ if $tranche_count < scalar @wait_event_tranches;
print $h "\n";
printf $h "#define NUM_INDIVIDUAL_LWLOCKS %s\n", $lastlockidx + 1;
diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index 2d43bf2cc13..ec9c345ffdf 100644
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -122,9 +122,8 @@ StaticAssertDecl((LW_VAL_EXCLUSIVE & LW_FLAG_MASK) == 0,
* own tranche. We absorb the names of these tranches from there into
* BuiltinTrancheNames here.
*
- * 2. There are some predefined tranches for built-in groups of locks.
- * These are listed in enum BuiltinTrancheIds in lwlock.h, and their names
- * appear in BuiltinTrancheNames[] below.
+ * 2. There are some predefined tranches for built-in groups of locks defined
+ * in lwlocklist.h. We absorb the names of these tranches, too.
*
* 3. Extensions can create new tranches, via either RequestNamedLWLockTranche
* or LWLockRegisterTranche. The names of these that are known in the current
@@ -135,49 +134,10 @@ StaticAssertDecl((LW_VAL_EXCLUSIVE & LW_FLAG_MASK) == 0,
*/
static const char *const BuiltinTrancheNames[] = {
#define PG_LWLOCK(id, lockname) [id] = CppAsString(lockname),
+#define PG_LWLOCKTRANCHE(id, lockname) [LWTRANCHE_##id] = CppAsString(lockname),
#include "storage/lwlocklist.h"
#undef PG_LWLOCK
- [LWTRANCHE_XACT_BUFFER] = "XactBuffer",
- [LWTRANCHE_COMMITTS_BUFFER] = "CommitTsBuffer",
- [LWTRANCHE_SUBTRANS_BUFFER] = "SubtransBuffer",
- [LWTRANCHE_MULTIXACTOFFSET_BUFFER] = "MultiXactOffsetBuffer",
- [LWTRANCHE_MULTIXACTMEMBER_BUFFER] = "MultiXactMemberBuffer",
- [LWTRANCHE_NOTIFY_BUFFER] = "NotifyBuffer",
- [LWTRANCHE_SERIAL_BUFFER] = "SerialBuffer",
- [LWTRANCHE_WAL_INSERT] = "WALInsert",
- [LWTRANCHE_BUFFER_CONTENT] = "BufferContent",
- [LWTRANCHE_REPLICATION_ORIGIN_STATE] = "ReplicationOriginState",
- [LWTRANCHE_REPLICATION_SLOT_IO] = "ReplicationSlotIO",
- [LWTRANCHE_LOCK_FASTPATH] = "LockFastPath",
- [LWTRANCHE_BUFFER_MAPPING] = "BufferMapping",
- [LWTRANCHE_LOCK_MANAGER] = "LockManager",
- [LWTRANCHE_PREDICATE_LOCK_MANAGER] = "PredicateLockManager",
- [LWTRANCHE_PARALLEL_HASH_JOIN] = "ParallelHashJoin",
- [LWTRANCHE_PARALLEL_BTREE_SCAN] = "ParallelBtreeScan",
- [LWTRANCHE_PARALLEL_QUERY_DSA] = "ParallelQueryDSA",
- [LWTRANCHE_PER_SESSION_DSA] = "PerSessionDSA",
- [LWTRANCHE_PER_SESSION_RECORD_TYPE] = "PerSessionRecordType",
- [LWTRANCHE_PER_SESSION_RECORD_TYPMOD] = "PerSessionRecordTypmod",
- [LWTRANCHE_SHARED_TUPLESTORE] = "SharedTupleStore",
- [LWTRANCHE_SHARED_TIDBITMAP] = "SharedTidBitmap",
- [LWTRANCHE_PARALLEL_APPEND] = "ParallelAppend",
- [LWTRANCHE_PER_XACT_PREDICATE_LIST] = "PerXactPredicateList",
- [LWTRANCHE_PGSTATS_DSA] = "PgStatsDSA",
- [LWTRANCHE_PGSTATS_HASH] = "PgStatsHash",
- [LWTRANCHE_PGSTATS_DATA] = "PgStatsData",
- [LWTRANCHE_LAUNCHER_DSA] = "LogicalRepLauncherDSA",
- [LWTRANCHE_LAUNCHER_HASH] = "LogicalRepLauncherHash",
- [LWTRANCHE_DSM_REGISTRY_DSA] = "DSMRegistryDSA",
- [LWTRANCHE_DSM_REGISTRY_HASH] = "DSMRegistryHash",
- [LWTRANCHE_COMMITTS_SLRU] = "CommitTsSLRU",
- [LWTRANCHE_MULTIXACTOFFSET_SLRU] = "MultiXactOffsetSLRU",
- [LWTRANCHE_MULTIXACTMEMBER_SLRU] = "MultiXactMemberSLRU",
- [LWTRANCHE_NOTIFY_SLRU] = "NotifySLRU",
- [LWTRANCHE_SERIAL_SLRU] = "SerialSLRU",
- [LWTRANCHE_SUBTRANS_SLRU] = "SubtransSLRU",
- [LWTRANCHE_XACT_SLRU] = "XactSLRU",
- [LWTRANCHE_PARALLEL_VACUUM_DSA] = "ParallelVacuumDSA",
- [LWTRANCHE_AIO_URING_COMPLETION] = "AioUringCompletion",
+#undef PG_LWLOCKTRANCHE
};
StaticAssertDecl(lengthof(BuiltinTrancheNames) ==
diff --git a/src/backend/utils/activity/wait_event_names.txt b/src/backend/utils/activity/wait_event_names.txt
index 4da68312b5f..0be307d2ca0 100644
--- a/src/backend/utils/activity/wait_event_names.txt
+++ b/src/backend/utils/activity/wait_event_names.txt
@@ -356,9 +356,13 @@ AioWorkerSubmissionQueue "Waiting to access AIO worker submission queue."
#
# END OF PREDEFINED LWLOCKS (DO NOT CHANGE THIS LINE)
#
-# Predefined LWLocks (i.e., those declared in lwlocknames.h) must be listed
-# in the section above and must be listed in the same order as in
-# lwlocknames.h. Other LWLocks must be listed in the section below.
+# Predefined LWLocks (i.e., those declared at the top of lwlocknames.h) must be
+# listed in the section above and must be listed in the same order as in
+# lwlocknames.h.
+#
+# Likewise, the built-in LWLock tranches (i.e., those declared at the bottom of
+# lwlocknames.h) must be listed in the section below and must be listed in the
+# same order as in lwlocknames.h.
#
XactBuffer "Waiting for I/O on a transaction status SLRU buffer."
diff --git a/src/include/storage/lwlock.h b/src/include/storage/lwlock.h
index 08a72569ae5..5e717765764 100644
--- a/src/include/storage/lwlock.h
+++ b/src/include/storage/lwlock.h
@@ -176,51 +176,23 @@ extern void LWLockInitialize(LWLock *lock, int tranche_id);
* Every tranche ID less than NUM_INDIVIDUAL_LWLOCKS is reserved; also,
* we reserve additional tranche IDs for builtin tranches not included in
* the set of individual LWLocks. A call to LWLockNewTrancheId will never
- * return a value less than LWTRANCHE_FIRST_USER_DEFINED.
+ * return a value less than LWTRANCHE_FIRST_USER_DEFINED. The actual list of
+ * built-in tranches is kept in lwlocklist.h.
*/
typedef enum BuiltinTrancheIds
{
- LWTRANCHE_XACT_BUFFER = NUM_INDIVIDUAL_LWLOCKS,
- LWTRANCHE_COMMITTS_BUFFER,
- LWTRANCHE_SUBTRANS_BUFFER,
- LWTRANCHE_MULTIXACTOFFSET_BUFFER,
- LWTRANCHE_MULTIXACTMEMBER_BUFFER,
- LWTRANCHE_NOTIFY_BUFFER,
- LWTRANCHE_SERIAL_BUFFER,
- LWTRANCHE_WAL_INSERT,
- LWTRANCHE_BUFFER_CONTENT,
- LWTRANCHE_REPLICATION_ORIGIN_STATE,
- LWTRANCHE_REPLICATION_SLOT_IO,
- LWTRANCHE_LOCK_FASTPATH,
- LWTRANCHE_BUFFER_MAPPING,
- LWTRANCHE_LOCK_MANAGER,
- LWTRANCHE_PREDICATE_LOCK_MANAGER,
- LWTRANCHE_PARALLEL_HASH_JOIN,
- LWTRANCHE_PARALLEL_BTREE_SCAN,
- LWTRANCHE_PARALLEL_QUERY_DSA,
- LWTRANCHE_PER_SESSION_DSA,
- LWTRANCHE_PER_SESSION_RECORD_TYPE,
- LWTRANCHE_PER_SESSION_RECORD_TYPMOD,
- LWTRANCHE_SHARED_TUPLESTORE,
- LWTRANCHE_SHARED_TIDBITMAP,
- LWTRANCHE_PARALLEL_APPEND,
- LWTRANCHE_PER_XACT_PREDICATE_LIST,
- LWTRANCHE_PGSTATS_DSA,
- LWTRANCHE_PGSTATS_HASH,
- LWTRANCHE_PGSTATS_DATA,
- LWTRANCHE_LAUNCHER_DSA,
- LWTRANCHE_LAUNCHER_HASH,
- LWTRANCHE_DSM_REGISTRY_DSA,
- LWTRANCHE_DSM_REGISTRY_HASH,
- LWTRANCHE_COMMITTS_SLRU,
- LWTRANCHE_MULTIXACTMEMBER_SLRU,
- LWTRANCHE_MULTIXACTOFFSET_SLRU,
- LWTRANCHE_NOTIFY_SLRU,
- LWTRANCHE_SERIAL_SLRU,
- LWTRANCHE_SUBTRANS_SLRU,
- LWTRANCHE_XACT_SLRU,
- LWTRANCHE_PARALLEL_VACUUM_DSA,
- LWTRANCHE_AIO_URING_COMPLETION,
+ /*
+ * LWTRANCHE_INVALID is an unused value that only exists to initialize the
+ * rest of the tranches to appropriate values.
+ */
+ LWTRANCHE_INVALID = NUM_INDIVIDUAL_LWLOCKS - 1,
+
+#define PG_LWLOCK(id, name)
+#define PG_LWLOCKTRANCHE(id, name) LWTRANCHE_##id,
+#include "storage/lwlocklist.h"
+#undef PG_LWLOCK
+#undef PG_LWLOCKTRANCHE
+
LWTRANCHE_FIRST_USER_DEFINED,
} BuiltinTrancheIds;
diff --git a/src/include/storage/lwlocklist.h b/src/include/storage/lwlocklist.h
index a9681738146..208d2e3a8ed 100644
--- a/src/include/storage/lwlocklist.h
+++ b/src/include/storage/lwlocklist.h
@@ -2,9 +2,10 @@
*
* lwlocklist.h
*
- * The predefined LWLock list is kept in its own source file for use by
- * automatic tools. The exact representation of a keyword is determined by
- * the PG_LWLOCK macro, which is not defined in this file; it can be
+ * The list of predefined LWLocks and built-in LWLock tranches is kept in
+ * its own source file for use by automatic tools. The exact
+ * representation of a keyword is determined by the PG_LWLOCK and
+ * PG_LWLOCKTRANCHE macros, which are not defined in this file; they can be
* defined by the caller for special purposes.
*
* Also, generate-lwlocknames.pl processes this file to create lwlocknames.h.
@@ -84,3 +85,53 @@ PG_LWLOCK(50, DSMRegistry)
PG_LWLOCK(51, InjectionPoint)
PG_LWLOCK(52, SerialControl)
PG_LWLOCK(53, AioWorkerSubmissionQueue)
+
+/*
+ * There also exist several built-in LWLock tranches. As with the predefined
+ * LWLocks, be sure to update the WaitEventLWLock section of
+ * src/backend/utils/activity/wait_event_names.txt when modifying this list.
+ *
+ * Note that the IDs here (the first value) don't include the LWTRANCHE_
+ * prefix. It's added elsewhere.
+ */
+PG_LWLOCKTRANCHE(XACT_BUFFER, XactBuffer)
+PG_LWLOCKTRANCHE(COMMITTS_BUFFER, CommitTsBuffer)
+PG_LWLOCKTRANCHE(SUBTRANS_BUFFER, SubtransBuffer)
+PG_LWLOCKTRANCHE(MULTIXACTOFFSET_BUFFER, MultiXactOffsetBuffer)
+PG_LWLOCKTRANCHE(MULTIXACTMEMBER_BUFFER, MultiXactMemberBuffer)
+PG_LWLOCKTRANCHE(NOTIFY_BUFFER, NotifyBuffer)
+PG_LWLOCKTRANCHE(SERIAL_BUFFER, SerialBuffer)
+PG_LWLOCKTRANCHE(WAL_INSERT, WALInsert)
+PG_LWLOCKTRANCHE(BUFFER_CONTENT, BufferContent)
+PG_LWLOCKTRANCHE(REPLICATION_ORIGIN_STATE, ReplicationOriginState)
+PG_LWLOCKTRANCHE(REPLICATION_SLOT_IO, ReplicationSlotIO)
+PG_LWLOCKTRANCHE(LOCK_FASTPATH, LockFastPath)
+PG_LWLOCKTRANCHE(BUFFER_MAPPING, BufferMapping)
+PG_LWLOCKTRANCHE(LOCK_MANAGER, LockManager)
+PG_LWLOCKTRANCHE(PREDICATE_LOCK_MANAGER, PredicateLockManager)
+PG_LWLOCKTRANCHE(PARALLEL_HASH_JOIN, ParallelHashJoin)
+PG_LWLOCKTRANCHE(PARALLEL_BTREE_SCAN, ParallelBtreeScan)
+PG_LWLOCKTRANCHE(PARALLEL_QUERY_DSA, ParallelQueryDSA)
+PG_LWLOCKTRANCHE(PER_SESSION_DSA, PerSessionDSA)
+PG_LWLOCKTRANCHE(PER_SESSION_RECORD_TYPE, PerSessionRecordType)
+PG_LWLOCKTRANCHE(PER_SESSION_RECORD_TYPMOD, PerSessionRecordTypmod)
+PG_LWLOCKTRANCHE(SHARED_TUPLESTORE, SharedTupleStore)
+PG_LWLOCKTRANCHE(SHARED_TIDBITMAP, SharedTidBitmap)
+PG_LWLOCKTRANCHE(PARALLEL_APPEND, ParallelAppend)
+PG_LWLOCKTRANCHE(PER_XACT_PREDICATE_LIST, PerXactPredicateList)
+PG_LWLOCKTRANCHE(PGSTATS_DSA, PgStatsDSA)
+PG_LWLOCKTRANCHE(PGSTATS_HASH, PgStatsHash)
+PG_LWLOCKTRANCHE(PGSTATS_DATA, PgStatsData)
+PG_LWLOCKTRANCHE(LAUNCHER_DSA, LogicalRepLauncherDSA)
+PG_LWLOCKTRANCHE(LAUNCHER_HASH, LogicalRepLauncherHash)
+PG_LWLOCKTRANCHE(DSM_REGISTRY_DSA, DSMRegistryDSA)
+PG_LWLOCKTRANCHE(DSM_REGISTRY_HASH, DSMRegistryHash)
+PG_LWLOCKTRANCHE(COMMITTS_SLRU, CommitTsSLRU)
+PG_LWLOCKTRANCHE(MULTIXACTOFFSET_SLRU, MultiXactOffsetSLRU)
+PG_LWLOCKTRANCHE(MULTIXACTMEMBER_SLRU, MultiXactMemberSLRU)
+PG_LWLOCKTRANCHE(NOTIFY_SLRU, NotifySLRU)
+PG_LWLOCKTRANCHE(SERIAL_SLRU, SerialSLRU)
+PG_LWLOCKTRANCHE(SUBTRANS_SLRU, SubtransSLRU)
+PG_LWLOCKTRANCHE(XACT_SLRU, XactSLRU)
+PG_LWLOCKTRANCHE(PARALLEL_VACUUM_DSA, ParallelVacuumDSA)
+PG_LWLOCKTRANCHE(AIO_URING_COMPLETION, AioUringCompletion)
--
2.34.1
