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Michael Paquier 404a17c155 Use single LWLock for lock statistics in pgstats
Previously, one LWLock was used for each lock type, adding complexity
without an observable performance benefit as data is gathered only for
paths involving lock waits, at least currently.  This commit replaces
the per-type set of LWLocks with a single LWLock protecting the stats
data of all the lock types, like the stats kinds for SLRU or WAL.  A
good chunk of the callbacks get simpler thanks to this change.

The previous approach also had one bug in the flush callback when nowait
was called with "true": a backend iterating over all entries could
successfully flush some entries while skipping others due to contention,
then unconditionally reset the pending data.  This would cause some
stats data loss.

Oversight in 4019f725f5.

Reported-by: Tomas Vondra <tomas@vondra.me>
Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/1af63e6d-16d5-4d5b-9b03-11472ef1adf9@vondra.me
2026-04-06 14:01:04 +09:00
.github Add CODE_OF_CONDUCT.md, CONTRIBUTING.md, and SECURITY.md. 2024-07-02 13:03:58 -05:00
config Compute CRC32C on ARM using the Crypto Extension where available 2026-04-04 20:47:01 +07:00
contrib Convert pg_stat_statements to use the new shmem allocation functions 2026-04-06 02:12:53 +03:00
doc Add wal_sender_shutdown_timeout GUC to limit shutdown wait for replication 2026-04-06 11:35:03 +09:00
src Use single LWLock for lock statistics in pgstats 2026-04-06 14:01:04 +09:00
.cirrus.star ci: Simplify ci-os-only handling 2025-08-14 12:09:34 -04:00
.cirrus.tasks.yml Enable test_cplusplusext with MSVC 2026-04-01 07:48:47 +02:00
.cirrus.yml ci: Per-repo configuration for manually trigger tasks 2025-08-14 11:54:03 -04:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Update .editorconfig and .gitattributes for postgresql.conf.sample. 2025-11-18 10:28:36 -06:00
.git-blame-ignore-revs Add commit 874da8b1f6 to .git-blame-ignore-revs. 2026-03-30 14:35:24 -05:00
.gitattributes Update .editorconfig and .gitattributes for postgresql.conf.sample. 2025-11-18 10:28:36 -06:00
.gitignore Update top-level .gitignore. 2022-12-04 15:23:00 -05:00
.mailmap Add a Git .mailmap file 2024-11-05 13:56:02 +01:00
aclocal.m4 autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
configure Compute CRC32C on ARM using the Crypto Extension where available 2026-04-04 20:47:01 +07:00
configure.ac Compute CRC32C on ARM using the Crypto Extension where available 2026-04-04 20:47:01 +07:00
COPYRIGHT Update copyright for 2026 2026-01-01 13:24:10 -05:00
GNUmakefile.in Allow selecting the git revision to be packaged by "make dist". 2024-05-03 11:08:50 -04:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Restore AIX support. 2026-02-23 13:34:22 -05:00
meson.build Compute CRC32C on ARM using the Crypto Extension where available 2026-04-04 20:47:01 +07:00
meson_options.txt Update copyright for 2026 2026-01-01 13:24:10 -05:00
README.md Revise the style of a paragraph in README.md. 2024-03-21 10:16:41 -05:00

PostgreSQL Database Management System

This directory contains the source code distribution of the PostgreSQL database management system.

PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.

Copyright and license information can be found in the file COPYRIGHT.

General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.

The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.