postgres

Andres Freund 91c40548d5 Fix XLogReader FD leak that makes backends unusable after 2PC usage. Before the fix every 2PC commit/abort leaked a file descriptor. As the files are opened using BasicOpenFile(), that quickly leads to the backend running out of file descriptors. Once enough 2PC abort/commit have caused enough FDs to leak, any IO in the backend will fail with "Too many open files", as BasicOpenFilePerm() will have triggered all open files known to fd.c to be closed. The leak causing the problem at hand is a consequence of `0dc8ead46`, but is only exascerbated by it. Previously most XLogPageReadCB callbacks used static variables to cache one open file, but after the commit the cache is private to each XLogReader instance. There never was infrastructure to close FDs at the time of XLogReaderFree, but the way XLogReader was used limited the leak to one FD. This commit just closes the during XLogReaderFree() if the FD is stored in XLogReaderState.seg.ws_segno. This may not be the way to solve this medium/long term, but at least unbreaks 2PC. Discussion: https://postgr.es/m/20200406025651.fpzdb5yyb7qyhqko@alap3.anarazel.de		6 years ago
config	Enable Unix-domain sockets support on Windows	6 years ago
contrib	Consider Incremental Sort paths at additional places	6 years ago
doc	Allow users to limit storage reserved by replication slots	6 years ago
src	Fix XLogReader FD leak that makes backends unusable after 2PC usage.	6 years ago
.dir-locals.el	…
.editorconfig	…
.gitattributes	…
.gitignore	…
COPYRIGHT	…
GNUmakefile.in	Add support for automatically updating Unicode derived files	6 years ago
HISTORY	Canonicalize some URLs	6 years ago
Makefile	…
README	Canonicalize some URLs	6 years ago
README.git	Canonicalize some URLs	6 years ago
aclocal.m4	…
configure	Enable Unix-domain sockets support on Windows	6 years ago
configure.in	Define EXEC_BACKEND in pg_config_manual.h	6 years ago

README

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.

PostgreSQL has many language interfaces, many of which are listed here:

	https://www.postgresql.org/download/

See the file INSTALL for instructions on how to build and install
PostgreSQL.  That file also lists supported operating systems and
hardware platforms and contains information regarding any other
software packages that are required to build or run the PostgreSQL
system.  Copyright and license information can be found in the
file COPYRIGHT.  A comprehensive documentation set is included in this
distribution; it can be read as described in the installation
instructions.

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