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Michael Paquier 818fefd8fd Fix race leading to incorrect conflict cause in InvalidatePossiblyObsoleteSlot()
The invalidation of an active slot is done in two steps:
- Termination of the backend holding it, if any.
- Report that the slot is obsolete, with a conflict cause depending on
the slot's data.

This can be racy because between these two steps the slot mutex would be
released while doing system calls, which means that the effective_xmin
and effective_catalog_xmin could advance during that time, detecting a
conflict cause different than the one originally wanted before the
process owning a slot is terminated.

Holding the mutex longer is not an option, so this commit changes the
code to record the LSNs stored in the slot during the termination of the
process owning the slot.

Bonus thanks to Alexander Lakhin for the various tests and the analysis.

Author: Bertrand Drouvot
Reviewed-by: Michael Paquier, Bharath Rupireddy
Discussion: https://postgr.es/m/ZaTjW2Xh+TQUCOH0@ip-10-97-1-34.eu-west-3.compute.internal
Backpatch-through: 16
2024-02-20 13:43:51 +09:00
config jit: Require at least LLVM 10. 2024-01-25 15:42:34 +13:00
contrib Use new overflow-safe integer comparison functions. 2024-02-16 14:05:36 -06:00
doc doc: Use system-username instead of system-user 2024-02-20 11:59:03 +09:00
src Fix race leading to incorrect conflict cause in InvalidatePossiblyObsoleteSlot() 2024-02-20 13:43:51 +09:00
.cirrus.star Remove duplicate words in docs and code comments. 2023-10-09 09:18:47 +05:30
.cirrus.tasks.yml ci: Add test coverage of different pg_upgrade modes 2024-02-19 09:31:23 +01:00
.cirrus.yml ci: Make compute resources for CI configurable 2023-08-23 15:15:28 -07:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Add .editorconfig 2019-12-18 09:13:13 +01:00
.git-blame-ignore-revs Add previous commit to .git-blame-ignore-revs 2024-02-09 11:06:32 +09:00
.gitattributes Remove non-existing file from .gitattributes 2024-02-16 11:39:09 +01:00
.gitignore Update top-level .gitignore. 2022-12-04 15:23:00 -05:00
aclocal.m4 autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
configure Fix gai_strerror() thread-safety on Windows. 2024-02-12 11:14:21 +13:00
configure.ac Fix gai_strerror() thread-safety on Windows. 2024-02-12 11:14:21 +13:00
COPYRIGHT Update copyright for 2024 2024-01-03 20:49:05 -05:00
GNUmakefile.in Stop generating plain-text INSTALL instructions. 2023-12-22 13:32:15 -05:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Stop generating plain-text INSTALL instructions. 2023-12-22 13:32:15 -05:00
meson.build jit: Require at least LLVM 10. 2024-01-25 15:42:34 +13:00
meson_options.txt Add backend support for injection points 2024-01-22 10:15:50 +09:00
README Stop generating plain-text INSTALL instructions. 2023-12-22 13:32:15 -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/.