Add test for connection limits

Reviewed-by: Andres Freund <[email protected]>
Discussion: https://www.postgresql.org/message-id/a102f15f-eac4-4ff2-af02-f9ff209ec66f@iki.fi

diff --git a/src/test/Makefile b/src/test/Makefile
index dbd3192874d3375c520ce08a72458b0d98741868..abdd6e5a985df1f27cfce5306a51148ba1488dcf 100644 (file)
--- a/src/test/Makefile
+++ b/src/test/Makefile
@@ -12,7 +12,7 @@ subdir = src/test
 top_builddir = ../..
 include $(top_builddir)/src/Makefile.global
 
-SUBDIRS = perl regress isolation modules authentication recovery subscription
+SUBDIRS = perl postmaster regress isolation modules authentication recovery subscription
 
 ifeq ($(with_icu),yes)
 SUBDIRS += icu

diff --git a/src/test/meson.build b/src/test/meson.build
index c3d0dfedf1c5f854800a6681f669dbb0d81b7857..67376e4b7fd6c95d32e9b16aec6affb84a5c9fdb 100644 (file)
--- a/src/test/meson.build
+++ b/src/test/meson.build
@@ -4,6 +4,7 @@ subdir('regress')
 subdir('isolation')
 
 subdir('authentication')
+subdir('postmaster')
 subdir('recovery')
 subdir('subscription')
 subdir('modules')

diff --git a/src/test/postmaster/Makefile b/src/test/postmaster/Makefile
new file mode 100644 (file)
index 0000000..dfcce9c
--- /dev/null
+++ b/src/test/postmaster/Makefile
@@ -0,0 +1,23 @@
+#-------------------------------------------------------------------------
+#
+# Makefile for src/test/postmaster
+#
+# Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
+# Portions Copyright (c) 1994, Regents of the University of California
+#
+# src/test/postmaster/Makefile
+#
+#-------------------------------------------------------------------------
+
+subdir = src/test/postmaster
+top_builddir = ../../..
+include $(top_builddir)/src/Makefile.global
+
+check:
+       $(prove_check)
+
+installcheck:
+       $(prove_installcheck)
+
+clean distclean:
+       rm -rf tmp_check

diff --git a/src/test/postmaster/README b/src/test/postmaster/README
new file mode 100644 (file)
index 0000000..7e47bf5
--- /dev/null
+++ b/src/test/postmaster/README
@@ -0,0 +1,27 @@
+src/test/postmaster/README
+
+Regression tests for postmaster
+===============================
+
+This directory contains a test suite for postmaster's handling of
+connections, connection limits, and startup/shutdown sequence.
+
+
+Running the tests
+=================
+
+NOTE: You must have given the --enable-tap-tests argument to configure.
+
+Run
+    make check
+or
+    make installcheck
+You can use "make installcheck" if you previously did "make install".
+In that case, the code in the installation tree is tested.  With
+"make check", a temporary installation tree is built from the current
+sources and then tested.
+
+Either way, this test initializes, starts, and stops a test Postgres
+cluster.
+
+See src/test/perl/README for more info about running these tests.

diff --git a/src/test/postmaster/meson.build b/src/test/postmaster/meson.build
new file mode 100644 (file)
index 0000000..c2de2e0
--- /dev/null
+++ b/src/test/postmaster/meson.build
@@ -0,0 +1,12 @@
+# Copyright (c) 2022-2024, PostgreSQL Global Development Group
+
+tests += {
+  'name': 'postmaster',
+  'sd': meson.current_source_dir(),
+  'bd': meson.current_build_dir(),
+  'tap': {
+    'tests': [
+      't/001_connection_limits.pl',
+    ],
+  },
+}

diff --git a/src/test/postmaster/t/001_connection_limits.pl b/src/test/postmaster/t/001_connection_limits.pl
new file mode 100644 (file)
index 0000000..f50aae4
--- /dev/null
+++ b/src/test/postmaster/t/001_connection_limits.pl
@@ -0,0 +1,79 @@
+
+# Copyright (c) 2021-2024, PostgreSQL Global Development Group
+
+# Test connection limits, i.e. max_connections, reserved_connections
+# and superuser_reserved_connections.
+
+use strict;
+use warnings FATAL => 'all';
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Test::More;
+
+# Initialize the server with specific low connection limits
+my $node = PostgreSQL::Test::Cluster->new('primary');
+$node->init;
+$node->append_conf('postgresql.conf', "max_connections = 6");
+$node->append_conf('postgresql.conf', "reserved_connections = 2");
+$node->append_conf('postgresql.conf', "superuser_reserved_connections = 1");
+$node->append_conf('postgresql.conf', "log_connections = on");
+$node->start;
+
+$node->safe_psql(
+       'postgres', qq{
+CREATE USER regress_regular LOGIN;
+CREATE USER regress_reserved LOGIN;
+GRANT pg_use_reserved_connections TO regress_reserved;
+CREATE USER regress_superuser LOGIN SUPERUSER;
+});
+
+# With the limits we set in postgresql.conf, we can establish:
+# - 3 connections for any user with no special privileges
+# - 2 more connections for users belonging to "pg_use_reserved_connections"
+# - 1 more connection for superuser
+
+sub background_psql_as_user
+{
+       my $user = shift;
+
+       return $node->background_psql(
+               'postgres',
+               on_error_die => 1,
+               extra_params => [ '-U', $user ]);
+}
+
+my @sessions = ();
+
+push(@sessions, background_psql_as_user('regress_regular'));
+push(@sessions, background_psql_as_user('regress_regular'));
+push(@sessions, background_psql_as_user('regress_regular'));
+$node->connect_fails(
+       "dbname=postgres user=regress_regular",
+       "reserved_connections limit",
+       expected_stderr =>
+         qr/FATAL:  remaining connection slots are reserved for roles with privileges of the "pg_use_reserved_connections" role/
+);
+
+push(@sessions, background_psql_as_user('regress_reserved'));
+push(@sessions, background_psql_as_user('regress_reserved'));
+$node->connect_fails(
+       "dbname=postgres user=regress_regular",
+       "reserved_connections limit",
+       expected_stderr =>
+         qr/FATAL:  remaining connection slots are reserved for roles with the SUPERUSER attribute/
+);
+
+push(@sessions, background_psql_as_user('regress_superuser'));
+$node->connect_fails(
+       "dbname=postgres user=regress_superuser",
+       "superuser_reserved_connections limit",
+       expected_stderr => qr/FATAL:  sorry, too many clients already/);
+
+# TODO: test that query cancellation is still possible
+
+foreach my $session (@sessions)
+{
+       $session->quit;
+}
+
+done_testing();