From 7e755fdb9c2ffe5bd2a3fe5db8dccd51eeac8d04 Mon Sep 17 00:00:00 2001
From: Andrew Dunstan <andrew@dunslane.net>
Date: Tue, 2 Jun 2026 11:28:15 -0400
Subject: [PATCH v12 3/3] Convert TAP tests to PostgreSQL::Test::Session

Convert tests that drove a long-lived background psql process (or
repeatedly spawned psql) to use the libpq Session object instead.  This
covers concurrent-session and asynchronous-query tests across contrib,
src/bin and src/test: amcheck, bloom, pg_visibility, test_decoding,
pg_amcheck, pg_upgrade, authentication, oauth_validator, test_aio,
test_checksums, test_misc, test_slru, xid_wraparound, postmaster,
recovery and subscription.
---
 contrib/amcheck/t/001_verify_heapam.pl        |  36 +-
 contrib/amcheck/t/002_cic.pl                  |   7 +-
 contrib/amcheck/t/003_cic_2pc.pl              |  64 ++-
 contrib/bloom/t/001_wal.pl                    |  44 +-
 .../t/001_concurrent_transaction.pl           |   9 +-
 contrib/test_decoding/t/001_repl_stats.pl     |  11 +-
 src/bin/pg_amcheck/t/004_verify_heapam.pl     |  97 +++--
 .../pg_upgrade/t/007_multixact_conversion.pl  |  30 +-
 src/test/authentication/t/001_password.pl     |  35 +-
 src/test/authentication/t/007_pre_auth.pl     |  34 +-
 .../modules/oauth_validator/t/001_server.pl   |  29 +-
 src/test/modules/test_aio/t/001_aio.pl        | 165 ++++---
 .../modules/test_aio/t/004_read_stream.pl     |  75 ++--
 .../modules/test_checksums/t/002_restarts.pl  |   7 +-
 .../test_checksums/t/003_standby_restarts.pl  |  13 +-
 .../modules/test_checksums/t/004_offline.pl   |   7 +-
 src/test/modules/test_misc/t/005_timeouts.pl  |  45 +-
 .../modules/test_misc/t/007_catcache_inval.pl |  24 +-
 .../t/010_index_concurrently_upsert.pl        | 406 ++++++------------
 .../modules/test_misc/t/011_lock_stats.pl     |  96 ++---
 .../test_misc/t/013_temp_obj_multisession.pl  |  26 +-
 src/test/modules/test_slru/t/001_multixact.pl |  17 +-
 .../xid_wraparound/t/001_emergency_vacuum.pl  |  16 +-
 .../modules/xid_wraparound/t/002_limits.pl    |  21 +-
 .../xid_wraparound/t/004_notify_freeze.pl     |  27 +-
 .../postmaster/t/002_connection_limits.pl     |  26 +-
 src/test/recovery/t/009_twophase.pl           |  16 +-
 src/test/recovery/t/013_crash_restart.pl      |   4 +-
 src/test/recovery/t/022_crash_temp_files.pl   |   4 +-
 src/test/recovery/t/031_recovery_conflict.pl  |  39 +-
 src/test/recovery/t/037_invalid_database.pl   |  45 +-
 .../t/040_standby_failover_slots_sync.pl      |  26 +-
 .../recovery/t/041_checkpoint_at_promote.pl   |  11 +-
 src/test/recovery/t/042_low_level_backup.pl   |  12 +-
 .../recovery/t/046_checkpoint_logical_slot.pl |  66 ++-
 .../t/047_checkpoint_physical_slot.pl         |  18 +-
 .../recovery/t/048_vacuum_horizon_floor.pl    |  40 +-
 src/test/recovery/t/049_wait_for_lsn.pl       | 156 ++++---
 .../recovery/t/050_redo_segment_missing.pl    |  14 +-
 .../recovery/t/051_effective_wal_level.pl     |  23 +-
 src/test/subscription/t/015_stream.pl         |  35 +-
 src/test/subscription/t/035_conflicts.pl      |  23 +-
 .../t/038_walsnd_shutdown_timeout.pl          |  15 +-
 43 files changed, 870 insertions(+), 1044 deletions(-)

diff --git a/contrib/amcheck/t/001_verify_heapam.pl b/contrib/amcheck/t/001_verify_heapam.pl
index e3fee19ae5d..9ea72179fcd 100644
--- a/contrib/amcheck/t/001_verify_heapam.pl
+++ b/contrib/amcheck/t/001_verify_heapam.pl
@@ -5,6 +5,7 @@ use strict;
 use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 
 use Test::More;
@@ -18,7 +19,9 @@ $node = PostgreSQL::Test::Cluster->new('test');
 $node->init(no_data_checksums => 1);
 $node->append_conf('postgresql.conf', 'autovacuum=off');
 $node->start;
-$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+my $session = PostgreSQL::Test::Session->new(node => $node);
+
+$session->do(q(CREATE EXTENSION amcheck));
 
 #
 # Check a table with data loaded but no corruption, freezing, etc.
@@ -49,7 +52,7 @@ detects_heap_corruption(
 # Check a corrupt table with all-frozen data
 #
 fresh_test_table('test');
-$node->safe_psql('postgres', q(VACUUM (FREEZE, DISABLE_PAGE_SKIPPING) test));
+$session->do(q(VACUUM (FREEZE, DISABLE_PAGE_SKIPPING) test));
 detects_no_corruption("verify_heapam('test')",
 	"all-frozen not corrupted table");
 corrupt_first_page('test');
@@ -81,7 +84,7 @@ sub relation_filepath
 	my ($relname) = @_;
 
 	my $pgdata = $node->data_dir;
-	my $rel = $node->safe_psql('postgres',
+	my $rel = $session->query_oneval(
 		qq(SELECT pg_relation_filepath('$relname')));
 	die "path not found for relation $relname" unless defined $rel;
 	return "$pgdata/$rel";
@@ -92,8 +95,8 @@ sub fresh_test_table
 {
 	my ($relname) = @_;
 
-	return $node->safe_psql(
-		'postgres', qq(
+	return $session->do(
+		qq(
 		DROP TABLE IF EXISTS $relname CASCADE;
 		CREATE TABLE $relname (a integer, b text);
 		ALTER TABLE $relname SET (autovacuum_enabled=false);
@@ -117,8 +120,8 @@ sub fresh_test_sequence
 {
 	my ($seqname) = @_;
 
-	return $node->safe_psql(
-		'postgres', qq(
+	return $session->do(
+		qq(
 		DROP SEQUENCE IF EXISTS $seqname CASCADE;
 		CREATE SEQUENCE $seqname
 			INCREMENT BY 13
@@ -134,8 +137,8 @@ sub advance_test_sequence
 {
 	my ($seqname) = @_;
 
-	return $node->safe_psql(
-		'postgres', qq(
+	return $session->query_oneval(
+		qq(
 		SELECT nextval('$seqname');
 	));
 }
@@ -145,10 +148,7 @@ sub set_test_sequence
 {
 	my ($seqname) = @_;
 
-	return $node->safe_psql(
-		'postgres', qq(
-		SELECT setval('$seqname', 102);
-	));
+	return $session->query_oneval(qq(SELECT setval('$seqname', 102)));
 }
 
 # Call SQL functions to reset the sequence
@@ -156,8 +156,8 @@ sub reset_test_sequence
 {
 	my ($seqname) = @_;
 
-	return $node->safe_psql(
-		'postgres', qq(
+	return $session->do(
+		qq(
 		ALTER SEQUENCE $seqname RESTART WITH 51
 	));
 }
@@ -169,6 +169,7 @@ sub corrupt_first_page
 	my ($relname) = @_;
 	my $relpath = relation_filepath($relname);
 
+	$session->close;
 	$node->stop;
 
 	my $fh;
@@ -191,6 +192,7 @@ sub corrupt_first_page
 	  or BAIL_OUT("close failed: $!");
 
 	$node->start;
+	$session->reconnect;
 }
 
 sub detects_heap_corruption
@@ -216,7 +218,7 @@ sub detects_corruption
 
 	my ($function, $testname, @re) = @_;
 
-	my $result = $node->safe_psql('postgres', qq(SELECT * FROM $function));
+	my $result = $session->query_tuples(qq(SELECT * FROM $function));
 	like($result, $_, $testname) for (@re);
 }
 
@@ -226,7 +228,7 @@ sub detects_no_corruption
 
 	my ($function, $testname) = @_;
 
-	my $result = $node->safe_psql('postgres', qq(SELECT * FROM $function));
+	my $result = $session->query_tuples(qq(SELECT * FROM $function));
 	is($result, '', $testname);
 }
 
diff --git a/contrib/amcheck/t/002_cic.pl b/contrib/amcheck/t/002_cic.pl
index 629d00c1d05..f2c7bc8653f 100644
--- a/contrib/amcheck/t/002_cic.pl
+++ b/contrib/amcheck/t/002_cic.pl
@@ -6,6 +6,7 @@ use strict;
 use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 
 use Test::More;
@@ -72,8 +73,8 @@ $node->safe_psql('postgres',
 	q(INSERT INTO quebec SELECT i FROM generate_series(1, 2) s(i);));
 
 # start background transaction
-my $in_progress_h = $node->background_psql('postgres');
-$in_progress_h->query_safe(q(BEGIN; SELECT pg_current_xact_id();));
+my $in_progress_h = PostgreSQL::Test::Session->new(node => $node);
+$in_progress_h->do(q(BEGIN; SELECT pg_current_xact_id();));
 
 # delete one row from table, while background transaction is in progress
 $node->safe_psql('postgres', q(DELETE FROM quebec WHERE i = 1;));
@@ -86,7 +87,7 @@ my $result = $node->psql('postgres',
 	q(SELECT bt_index_parent_check('oscar', heapallindexed => true)));
 is($result, '0', 'bt_index_parent_check for CIC after removed row');
 
-$in_progress_h->quit;
+$in_progress_h->close;
 
 $node->stop;
 done_testing();
diff --git a/contrib/amcheck/t/003_cic_2pc.pl b/contrib/amcheck/t/003_cic_2pc.pl
index f28eeac17ef..d3a1643bf33 100644
--- a/contrib/amcheck/t/003_cic_2pc.pl
+++ b/contrib/amcheck/t/003_cic_2pc.pl
@@ -7,6 +7,7 @@ use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
+use PostgreSQL::Test::Session;
 
 use Test::More;
 
@@ -36,29 +37,42 @@ $node->safe_psql('postgres', q(CREATE TABLE tbl(i int, j jsonb)));
 # statements.
 #
 
-my $main_h = $node->background_psql('postgres');
+my $main_h = PostgreSQL::Test::Session->new(node=>$node);
 
-$main_h->query_safe(
+$main_h->do_async(
 	q(
 BEGIN;
 INSERT INTO tbl VALUES(0, '[[14,2,3]]');
 ));
 
-my $cic_h = $node->background_psql('postgres');
+my $cic_h = PostgreSQL::Test::Session->new(node=>$node);
 
-$cic_h->query_until(
-	qr/start/, q(
-\echo start
-CREATE INDEX CONCURRENTLY idx ON tbl(i);
-CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
+$cic_h->setnonblocking(1);
+
+$cic_h->enterPipelineMode();
+
+$cic_h->do_pipeline(
+	q(
+CREATE INDEX CONCURRENTLY idx ON tbl(i)
+));
+
+$cic_h->pipelineSync();
+
+$cic_h->do_pipeline(
+	q(
+CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j)
 ));
 
-$main_h->query_safe(
+$cic_h->pipelineSync();
+
+$main_h->wait_for_completion;
+$main_h->do_async(
 	q(
 PREPARE TRANSACTION 'a';
 ));
 
-$main_h->query_safe(
+$main_h->wait_for_completion;
+$main_h->do_async(
 	q(
 BEGIN;
 INSERT INTO tbl VALUES(0, '[[14,2,3]]');
@@ -66,7 +80,8 @@ INSERT INTO tbl VALUES(0, '[[14,2,3]]');
 
 $node->safe_psql('postgres', q(COMMIT PREPARED 'a';));
 
-$main_h->query_safe(
+$main_h->wait_for_completion;
+$main_h->do_async(
 	q(
 PREPARE TRANSACTION 'b';
 BEGIN;
@@ -75,14 +90,17 @@ INSERT INTO tbl VALUES(0, '"mary had a little lamb"');
 
 $node->safe_psql('postgres', q(COMMIT PREPARED 'b';));
 
-$main_h->query_safe(
-	q(
-PREPARE TRANSACTION 'c';
-COMMIT PREPARED 'c';
-));
+$main_h->wait_for_completion;
+$main_h->do(
+	q(PREPARE TRANSACTION 'c';),
+	q(COMMIT PREPARED 'c';));
 
-$main_h->quit;
-$cic_h->quit;
+$main_h->close;
+
+# called twice out of an abundance of caution about pipeline mode
+$cic_h->wait_for_completion;
+$cic_h->wait_for_completion;
+$cic_h->close;
 
 $result = $node->psql('postgres', q(SELECT bt_index_check('idx',true)));
 is($result, '0', 'bt_index_check after overlapping 2PC');
@@ -106,10 +124,9 @@ PREPARE TRANSACTION 'persists_forever';
 ));
 $node->restart;
 
-my $reindex_h = $node->background_psql('postgres');
-$reindex_h->query_until(
-	qr/start/, q(
-\echo start
+my $reindex_h = PostgreSQL::Test::Session->new(node => $node);
+$reindex_h->do_async(
+	q(
 DROP INDEX CONCURRENTLY idx;
 CREATE INDEX CONCURRENTLY idx ON tbl(i);
 DROP INDEX CONCURRENTLY ginidx;
@@ -117,7 +134,8 @@ CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
 ));
 
 $node->safe_psql('postgres', "COMMIT PREPARED 'spans_restart'");
-$reindex_h->quit;
+$reindex_h->wait_for_completion;
+$reindex_h->close;
 $result = $node->psql('postgres', q(SELECT bt_index_check('idx',true)));
 is($result, '0', 'bt_index_check after 2PC and restart');
 $result = $node->psql('postgres', q(SELECT gin_index_check('ginidx')));
diff --git a/contrib/bloom/t/001_wal.pl b/contrib/bloom/t/001_wal.pl
index 683b1876055..f86c49d6357 100644
--- a/contrib/bloom/t/001_wal.pl
+++ b/contrib/bloom/t/001_wal.pl
@@ -5,11 +5,14 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
 my $node_primary;
 my $node_standby;
+my $session_primary;
+my $session_standby;
 
 # Run few queries on both primary and standby and check their results match.
 sub test_index_replay
@@ -21,20 +24,18 @@ sub test_index_replay
 	# Wait for standby to catch up
 	$node_primary->wait_for_catchup($node_standby);
 
-	my $queries = qq(SET enable_seqscan=off;
-SET enable_bitmapscan=on;
-SET enable_indexscan=on;
-SELECT * FROM tst WHERE i = 0;
-SELECT * FROM tst WHERE i = 3;
-SELECT * FROM tst WHERE t = 'b';
-SELECT * FROM tst WHERE t = 'f';
-SELECT * FROM tst WHERE i = 3 AND t = 'c';
-SELECT * FROM tst WHERE i = 7 AND t = 'e';
-);
+	my @queries = (
+		"SELECT * FROM tst WHERE i = 0",
+		"SELECT * FROM tst WHERE i = 3",
+		"SELECT * FROM tst WHERE t = 'b'",
+		"SELECT * FROM tst WHERE t = 'f'",
+		"SELECT * FROM tst WHERE i = 3 AND t = 'c'",
+		"SELECT * FROM tst WHERE i = 7 AND t = 'e'",
+	   );
 
 	# Run test queries and compare their result
-	my $primary_result = $node_primary->safe_psql("postgres", $queries);
-	my $standby_result = $node_standby->safe_psql("postgres", $queries);
+	my $primary_result = $session_primary->query_tuples(@queries);
+	my $standby_result = $session_standby->query_tuples(@queries);
 
 	is($primary_result, $standby_result, "$test_name: query result matches");
 	return;
@@ -55,13 +56,24 @@ $node_standby->init_from_backup($node_primary, $backup_name,
 	has_streaming => 1);
 $node_standby->start;
 
+# Create and initialize the sessions
+$session_primary = PostgreSQL::Test::Session->new(node => $node_primary);
+$session_standby = PostgreSQL::Test::Session->new(node => $node_standby);
+my $initset = q[
+   SET enable_seqscan=off;
+   SET enable_bitmapscan=on;
+   SET enable_indexscan=on;
+];
+$session_primary->do($initset);
+$session_standby->do($initset);
+
 # Create some bloom index on primary
-$node_primary->safe_psql("postgres", "CREATE EXTENSION bloom;");
-$node_primary->safe_psql("postgres", "CREATE TABLE tst (i int4, t text);");
-$node_primary->safe_psql("postgres",
+$session_primary->do("CREATE EXTENSION bloom;");
+$session_primary->do("CREATE TABLE tst (i int4, t text);");
+$session_primary->do(
 	"INSERT INTO tst SELECT i%10, substr(encode(sha256(i::text::bytea), 'hex'), 1, 1) FROM generate_series(1,10000) i;"
 );
-$node_primary->safe_psql("postgres",
+$session_primary->do(
 	"CREATE INDEX bloomidx ON tst USING bloom (i, t) WITH (col1 = 3);");
 
 # Test that queries give same result
diff --git a/contrib/pg_visibility/t/001_concurrent_transaction.pl b/contrib/pg_visibility/t/001_concurrent_transaction.pl
index 3aa556892a6..cf6e3b45182 100644
--- a/contrib/pg_visibility/t/001_concurrent_transaction.pl
+++ b/contrib/pg_visibility/t/001_concurrent_transaction.pl
@@ -6,6 +6,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -24,10 +25,10 @@ $standby->start;
 
 # Setup another database
 $node->safe_psql("postgres", "CREATE DATABASE other_database;\n");
-my $bsession = $node->background_psql('other_database');
+my $bsession = PostgreSQL::Test::Session->new(node => $node, dbname => 'other_database');
 
 # Run a concurrent transaction
-$bsession->query_safe(
+$bsession->do(
 	qq[
 	BEGIN;
 	SELECT txid_current();
@@ -55,8 +56,8 @@ $result = $standby->safe_psql("postgres",
 ok($result eq "", "pg_check_visible() detects no errors");
 
 # Shutdown
-$bsession->query_safe("COMMIT;");
-$bsession->quit;
+$bsession->do("COMMIT;");
+$bsession->close;
 $node->stop;
 $standby->stop;
 
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 6814c792e2b..79b9182014f 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -7,6 +7,7 @@ use strict;
 use warnings FATAL => 'all';
 use File::Path qw(rmtree);
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -129,11 +130,11 @@ $node->safe_psql('postgres',
 );
 
 # Look at slot data, with a persistent connection.
-my $bpgsql = $node->background_psql('postgres', on_error_stop => 1);
+my $bgsession = PostgreSQL::Test::Session->new(node=>$node);
 
 # Launch query and look at slot data, incrementing the refcount of the
 # stats entry.
-$bpgsql->query_safe(
+$bgsession->do_async(
 	"SELECT pg_logical_slot_peek_binary_changes('$slot_name_restart', NULL, NULL)"
 );
 
@@ -150,7 +151,8 @@ $node->safe_psql('postgres',
 
 # Look again at the slot data.  The local stats reference should be refreshed
 # to the reinitialized entry.
-$bpgsql->query_safe(
+$bgsession->wait_for_completion;
+$bgsession->do_async(
 	"SELECT pg_logical_slot_peek_binary_changes('$slot_name_restart', NULL, NULL)"
 );
 # Drop again the slot, the entry is not dropped yet as the previous session
@@ -176,6 +178,7 @@ command_like(
 my $stats_file = "$datadir/pg_stat/pgstat.stat";
 ok(-f "$stats_file", "stats file must exist after shutdown");
 
-$bpgsql->quit;
+$bgsession->wait_for_completion;
+$bgsession->close;
 
 done_testing();
diff --git a/src/bin/pg_amcheck/t/004_verify_heapam.pl b/src/bin/pg_amcheck/t/004_verify_heapam.pl
index 95f1f34c90d..9afacbcaaea 100644
--- a/src/bin/pg_amcheck/t/004_verify_heapam.pl
+++ b/src/bin/pg_amcheck/t/004_verify_heapam.pl
@@ -5,6 +5,7 @@ use strict;
 use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 
 use Test::More;
@@ -190,16 +191,17 @@ $node->append_conf('postgresql.conf', 'max_prepared_transactions=10');
 $node->start;
 my $port = $node->port;
 my $pgdata = $node->data_dir;
-$node->safe_psql('postgres', "CREATE EXTENSION amcheck");
-$node->safe_psql('postgres', "CREATE EXTENSION pageinspect");
+my $session = PostgreSQL::Test::Session->new(node => $node);
+$session->do("CREATE EXTENSION amcheck");
+$session->do("CREATE EXTENSION pageinspect");
 
 # Get a non-zero datfrozenxid
-$node->safe_psql('postgres', qq(VACUUM FREEZE));
+$session->do(qq(VACUUM FREEZE));
 
 # Create the test table with precisely the schema that our corruption function
 # expects.
-$node->safe_psql(
-	'postgres', qq(
+$session->do(
+	qq(
 		CREATE TABLE public.test (a BIGINT, b TEXT, c TEXT);
 		ALTER TABLE public.test SET (autovacuum_enabled=false);
 		ALTER TABLE public.test ALTER COLUMN c SET STORAGE EXTERNAL;
@@ -209,14 +211,15 @@ $node->safe_psql(
 # We want (0 < datfrozenxid < test.relfrozenxid).  To achieve this, we freeze
 # an otherwise unused table, public.junk, prior to inserting data and freezing
 # public.test
-$node->safe_psql(
-	'postgres', qq(
+$session->do(
+	qq(
 		CREATE TABLE public.junk AS SELECT 'junk'::TEXT AS junk_column;
 		ALTER TABLE public.junk SET (autovacuum_enabled=false);
-		VACUUM FREEZE public.junk
-	));
+	),
+	'VACUUM FREEZE public.junk'
+);
 
-my $rel = $node->safe_psql('postgres',
+my $rel = $session->query_oneval(
 	qq(SELECT pg_relation_filepath('public.test')));
 my $relpath = "$pgdata/$rel";
 
@@ -229,23 +232,24 @@ my $ROWCOUNT_BASIC = 16;
 
 # First insert data needed for tests unrelated to update chain validation.
 # Then freeze the page. These tuples are at offset numbers 1 to 16.
-$node->safe_psql(
-	'postgres', qq(
+$session->do(
+	qq(
 	INSERT INTO public.test (a, b, c)
 		SELECT
 			x'DEADF9F9DEADF9F9'::bigint,
 			'abcdefg',
 			repeat('w', 10000)
 	FROM generate_series(1, $ROWCOUNT_BASIC);
-	VACUUM FREEZE public.test;)
+    ),
+	'VACUUM FREEZE public.test'
 );
 
 # Create some simple HOT update chains for line pointer validation. After
 # the page is HOT pruned, we'll have two redirects line pointers each pointing
 # to a tuple. We'll then change the second redirect to point to the same
 # tuple as the first one and verify that we can detect corruption.
-$node->safe_psql(
-	'postgres', qq(
+$session->do(
+	qq(
 		INSERT INTO public.test (a, b, c)
 			VALUES ( x'DEADF9F9DEADF9F9'::bigint, 'abcdefg',
 					 generate_series(1,2)); -- offset numbers 17 and 18
@@ -254,8 +258,8 @@ $node->safe_psql(
 	));
 
 # Create some more HOT update chains.
-$node->safe_psql(
-	'postgres', qq(
+$session->do(
+	qq(
 		INSERT INTO public.test (a, b, c)
 			VALUES ( x'DEADF9F9DEADF9F9'::bigint, 'abcdefg',
 					 generate_series(3,6)); -- offset numbers 21 through 24
@@ -264,25 +268,30 @@ $node->safe_psql(
 	));
 
 # Negative test case of HOT-pruning with aborted tuple.
-$node->safe_psql(
-	'postgres', qq(
+$session->do(
+	qq(
 		BEGIN;
 		UPDATE public.test SET c = 'a' WHERE c = '5'; -- offset number 27
 		ABORT;
-		VACUUM FREEZE public.test;
-	));
+       ),
+	   'VACUUM FREEZE public.test;',
+	);
 
 # Next update on any tuple will be stored at the same place of tuple inserted
 # by aborted transaction. This should not cause the table to appear corrupt.
-$node->safe_psql(
-	'postgres', qq(
+$session->do(
+	qq(
+        BEGIN;
 		UPDATE public.test SET c = 'a' WHERE c = '6'; -- offset number 27 again
-		VACUUM FREEZE public.test;
-	));
+        COMMIT;
+	),
+	'VACUUM FREEZE public.test;',
+   );
 
 # Data for HOT chain validation, so not calling VACUUM FREEZE.
-$node->safe_psql(
-	'postgres', qq(
+$session->do(
+	qq(
+        BEGIN;
 		INSERT INTO public.test (a, b, c)
 			VALUES ( x'DEADF9F9DEADF9F9'::bigint, 'abcdefg',
 					 generate_series(7,15)); -- offset numbers 28 to 36
@@ -293,11 +302,12 @@ $node->safe_psql(
 		UPDATE public.test SET c = 'a' WHERE c = '13'; -- offset number 41
 		UPDATE public.test SET c = 'a' WHERE c = '14'; -- offset number 42
 		UPDATE public.test SET c = 'a' WHERE c = '15'; -- offset number 43
+        COMMIT;
 	));
 
 # Need one aborted transaction to test corruption in HOT chains.
-$node->safe_psql(
-	'postgres', qq(
+$session->do(
+	qq(
 		BEGIN;
 		UPDATE public.test SET c = 'a' WHERE c = '9'; -- offset number 44
 		ABORT;
@@ -306,19 +316,19 @@ $node->safe_psql(
 # Need one in-progress transaction to test few corruption in HOT chains.
 # We are creating PREPARE TRANSACTION here as these will not be aborted
 # even if we stop the node.
-$node->safe_psql(
-	'postgres', qq(
+$session->do(
+	qq(
 		BEGIN;
 		PREPARE TRANSACTION 'in_progress_tx';
 	));
-my $in_progress_xid = $node->safe_psql(
-	'postgres', qq(
+my $in_progress_xid = $session->query_oneval(
+	qq(
 		SELECT transaction FROM pg_prepared_xacts;
 	));
 
-my $relfrozenxid = $node->safe_psql('postgres',
+my $relfrozenxid = $session->query_oneval(
 	q(select relfrozenxid from pg_class where relname = 'test'));
-my $datfrozenxid = $node->safe_psql('postgres',
+my $datfrozenxid = $session->query_oneval(
 	q(select datfrozenxid from pg_database where datname = 'postgres'));
 
 # Sanity check that our 'test' table has a relfrozenxid newer than the
@@ -326,6 +336,7 @@ my $datfrozenxid = $node->safe_psql('postgres',
 # first normal xid.  We rely on these invariants in some of our tests.
 if ($datfrozenxid <= 3 || $datfrozenxid >= $relfrozenxid)
 {
+	$session->close;
 	$node->clean_node;
 	plan skip_all =>
 	  "Xid thresholds not as expected: got datfrozenxid = $datfrozenxid, relfrozenxid = $relfrozenxid";
@@ -334,17 +345,21 @@ if ($datfrozenxid <= 3 || $datfrozenxid >= $relfrozenxid)
 
 # Find where each of the tuples is located on the page. If a particular
 # line pointer is a redirect rather than a tuple, we record the offset as -1.
-my @lp_off = split '\n', $node->safe_psql(
-	'postgres', qq(
+my $lp_off_res = $session->query(
+	qq(
 	    SELECT CASE WHEN lp_flags = 2 THEN -1 ELSE lp_off END
 	    FROM heap_page_items(get_raw_page('test', 'main', 0))
     )
-);
+   );
+my @lp_off;
+push(@lp_off, $_->[0]) foreach @{$lp_off_res->{rows}};
+
 scalar @lp_off == $ROWCOUNT or BAIL_OUT("row offset counts mismatch");
 
 # Sanity check that our 'test' table on disk layout matches expectations.  If
 # this is not so, we will have to skip the test until somebody updates the test
 # to work on this platform.
+$session->close;
 $node->stop;
 my $file;
 open($file, '+<', $relpath)
@@ -751,17 +766,19 @@ for (my $tupidx = 0; $tupidx < $ROWCOUNT; $tupidx++)
 close($file)
   or BAIL_OUT("close failed: $!");
 $node->start;
+$session->reconnect;
 
 # Run pg_amcheck against the corrupt table with epoch=0, comparing actual
 # corruption messages against the expected messages
 $node->command_checks_all(
 	[ 'pg_amcheck', '--no-dependent-indexes', '--port' => $port, 'postgres' ],
 	2, [@expected], [], 'Expected corruption message output');
-$node->safe_psql(
-	'postgres', qq(
+$session->do(
+	qq(
                         COMMIT PREPARED 'in_progress_tx';
         ));
 
+$session->close;
 $node->teardown_node;
 $node->clean_node;
 
diff --git a/src/bin/pg_upgrade/t/007_multixact_conversion.pl b/src/bin/pg_upgrade/t/007_multixact_conversion.pl
index 867a0623153..67e8f9334a4 100644
--- a/src/bin/pg_upgrade/t/007_multixact_conversion.pl
+++ b/src/bin/pg_upgrade/t/007_multixact_conversion.pl
@@ -15,6 +15,7 @@ use warnings FATAL => 'all';
 
 use Math::BigInt;
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -38,10 +39,8 @@ my $tempdir = PostgreSQL::Test::Utils::tempdir;
 # versions.
 #
 # The first argument is the cluster to connect to, the second argument
-# is a cluster using the new version.  We need the 'psql' binary from
-# the new version, the new cluster is otherwise unused.  (We need to
-# use the new 'psql' because some of the more advanced background psql
-# perl module features depend on a fairly recent psql version.)
+# is a cluster using the new version.  We need the libpq library from
+# the new version (for Session), the new cluster is otherwise unused.
 sub mxact_workload
 {
 	my $node = shift;       # Cluster to connect to
@@ -79,18 +78,15 @@ sub mxact_workload
 	# in each connection.
 	for (0 .. $nclients)
 	{
-		# Use the psql binary from the new installation.  The
-		# BackgroundPsql functionality doesn't work with older psql
-		# versions.
-		my $conn = $binnode->background_psql(
-			'',
+		# Use the libpq/Session infrastructure from the new installation.
+		my $conn = PostgreSQL::Test::Session->new(
 			connstr => $node->connstr('postgres'),
-			timeout => $connection_timeout_secs);
+			libdir => $binnode->config_data('--libdir'));
 
-		$conn->query_safe("SET log_statement=none", verbose => $verbose)
+		$conn->do("SET log_statement=none")
 		  unless $verbose;
-		$conn->query_safe("SET enable_seqscan=off", verbose => $verbose);
-		$conn->query_safe("BEGIN", verbose => $verbose);
+		$conn->do("SET enable_seqscan=off");
+		$conn->do("BEGIN");
 
 		push(@connections, $conn);
 	}
@@ -108,9 +104,9 @@ sub mxact_workload
 		my $conn = $connections[ $i % $nclients ];
 
 		my $sql = ($i % $abort_every == 0) ? "ABORT" : "COMMIT";
-		$conn->query_safe($sql, verbose => $verbose);
+		$conn->do($sql);
 
-		$conn->query_safe("BEGIN", verbose => $verbose);
+		$conn->do("BEGIN");
 		if ($i % $update_every == 0)
 		{
 			$sql = qq[
@@ -126,12 +122,12 @@ sub mxact_workload
 			  ) as x
 			];
 		}
-		$conn->query_safe($sql, verbose => $verbose);
+		$conn->do($sql);
 	}
 
 	for my $conn (@connections)
 	{
-		$conn->quit();
+		$conn->close;
 	}
 
 	$node->stop;
diff --git a/src/test/authentication/t/001_password.pl b/src/test/authentication/t/001_password.pl
index 69ed4919b16..ac2aa3ce23e 100644
--- a/src/test/authentication/t/001_password.pl
+++ b/src/test/authentication/t/001_password.pl
@@ -13,6 +13,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 if (!$use_unix_sockets)
@@ -185,36 +186,18 @@ my $res = $node->safe_psql(
 	 WHERE rolname = 'scram_role_iter'");
 is($res, 'SCRAM-SHA-256$1024:', 'scram_iterations in server side ROLE');
 
-# If we don't have IO::Pty, forget it, because IPC::Run depends on that
-# to support pty connections. Also skip if IPC::Run isn't at least 0.98
-# as earlier version cause the session to time out.
-SKIP:
-{
-	skip "IO::Pty and IPC::Run >= 0.98 required", 1
-	  unless eval { require IO::Pty; IPC::Run->VERSION('0.98'); };
+# set password using PQchangePassword
+my $session = PostgreSQL::Test::Session->new (node => $node);
 
-	# Alter the password on the created role using \password in psql to ensure
-	# that clientside password changes use the scram_iterations value when
-	# calculating SCRAM secrets.
-	my $session = $node->interactive_psql('postgres');
-
-	$session->set_query_timer_restart();
-	$session->query("SET password_encryption='scram-sha-256';");
-	$session->query("SET scram_iterations=42;");
-	$session->query_until(qr/Enter new password/,
-		"\\password scram_role_iter\n");
-	$session->query_until(qr/Enter it again/, "pass\n");
-	$session->query_until(qr/postgres=# /, "pass\n");
-	$session->quit;
-
-	$res = $node->safe_psql(
-		'postgres',
+$session->do("SET password_encryption='scram-sha-256';",
+			 "SET scram_iterations=42;");
+$res = $session->set_password("scram_role_iter","pass");
+is($res->{status}, 1, "set password ok");
+$res = $session->query_oneval(
 		"SELECT substr(rolpassword,1,17)
 		 FROM pg_authid
 		 WHERE rolname = 'scram_role_iter'");
-	is($res, 'SCRAM-SHA-256$42:',
-		'scram_iterations in psql \password command');
-}
+is($res, 'SCRAM-SHA-256$42:', 'scram_iterations correct');
 
 # Create a database to test regular expression.
 $node->safe_psql('postgres', "CREATE database regex_testdb;");
diff --git a/src/test/authentication/t/007_pre_auth.pl b/src/test/authentication/t/007_pre_auth.pl
index 04063f4721d..17de92bc41a 100644
--- a/src/test/authentication/t/007_pre_auth.pl
+++ b/src/test/authentication/t/007_pre_auth.pl
@@ -7,6 +7,7 @@ use strict;
 use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Time::HiRes qw(usleep);
 use Test::More;
@@ -36,24 +37,27 @@ if (!$node->check_extension('injection_points'))
 $node->safe_psql('postgres', 'CREATE EXTENSION injection_points');
 
 # Connect to the server and inject a waitpoint.
-my $psql = $node->background_psql('postgres');
-$psql->query_safe("SELECT injection_points_attach('init-pre-auth', 'wait')");
+my $session = PostgreSQL::Test::Session->new(node => $node);
+$session->do("SELECT injection_points_attach('init-pre-auth', 'wait')");
 
 # From this point on, all new connections will hang during startup, just before
-# authentication. Use the $psql connection handle for server interaction.
-my $conn = $node->background_psql('postgres', wait => 0);
+# authentication. Use the $session connection handle for server interaction.
+my $conn = PostgreSQL::Test::Session->new(node => $node, wait => 0);
 
 # Wait for the connection to show up in pg_stat_activity, with the wait_event
-# of the injection point.
+# of the injection point. We need to poll the async connection to drive it forward.
 my $pid;
 while (1)
 {
-	$pid = $psql->query(
+	# Drive the async connection forward - it won't progress without polling
+	$conn->poll_connect();
+
+	$pid = $session->query_oneval(
 		qq{SELECT pid FROM pg_stat_activity
   WHERE backend_type = 'client backend'
     AND state = 'starting'
-    AND wait_event = 'init-pre-auth';});
-	last if $pid ne "";
+    AND wait_event = 'init-pre-auth';}, 1);
+	last if defined $pid && $pid ne "";
 
 	usleep(100_000);
 }
@@ -62,24 +66,24 @@ note "backend $pid is authenticating";
 ok(1, 'authenticating connections are recorded in pg_stat_activity');
 
 # Detach the waitpoint and wait for the connection to complete.
-$psql->query_safe("SELECT injection_points_wakeup('init-pre-auth');");
+$session->do("SELECT injection_points_wakeup('init-pre-auth')");
 $conn->wait_connect();
 
 # Make sure the pgstat entry is updated eventually.
 while (1)
 {
 	my $state =
-	  $psql->query("SELECT state FROM pg_stat_activity WHERE pid = $pid;");
-	last if $state eq "idle";
+	  $session->query_oneval("SELECT state FROM pg_stat_activity WHERE pid = $pid");
+	last if defined $state && $state eq "idle";
 
-	note "state for backend $pid is '$state'; waiting for 'idle'...";
+	note "state for backend $pid is '" . ($state // 'undef') . "'; waiting for 'idle'...";
 	usleep(100_000);
 }
 
 ok(1, 'authenticated connections reach idle state in pg_stat_activity');
 
-$psql->query_safe("SELECT injection_points_detach('init-pre-auth');");
-$psql->quit();
-$conn->quit();
+$session->do("SELECT injection_points_detach('init-pre-auth')");
+$session->close();
+$conn->close();
 
 done_testing();
diff --git a/src/test/modules/oauth_validator/t/001_server.pl b/src/test/modules/oauth_validator/t/001_server.pl
index 1619fbffd45..3d4eb1bfe30 100644
--- a/src/test/modules/oauth_validator/t/001_server.pl
+++ b/src/test/modules/oauth_validator/t/001_server.pl
@@ -12,6 +12,7 @@ use warnings FATAL => 'all';
 use JSON::PP     qw(encode_json);
 use MIME::Base64 qw(encode_base64);
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -57,7 +58,7 @@ $node->safe_psql('postgres', 'CREATE USER testalt;');
 $node->safe_psql('postgres', 'CREATE USER testparam;');
 
 # Save a background connection for later configuration changes.
-my $bgconn = $node->background_psql('postgres');
+my $bgconn = PostgreSQL::Test::Session->new(node => $node);
 
 my $webserver = OAuth::Server->new();
 $webserver->run();
@@ -124,11 +125,11 @@ $log_start =
   $node->wait_for_log(qr/reloading configuration files/, $log_start);
 
 # Check pg_hba_file_rules() support.
-my $contents = $bgconn->query_safe(
+my $contents = $bgconn->query(
 	qq(SELECT rule_number, auth_method, options
 		 FROM pg_hba_file_rules
 		 ORDER BY rule_number;));
-is( $contents,
+is( $contents->{psqlout},
 	qq{1|oauth|\{issuer=$issuer,"scope=openid postgres",validator=validator\}
 2|oauth|\{issuer=$issuer/.well-known/oauth-authorization-server/alternate,"scope=openid postgres alt",validator=validator\}
 3|oauth|\{issuer=$issuer/param,"scope=openid postgres",validator=validator\}},
@@ -551,7 +552,7 @@ $common_connstr =
   "dbname=postgres oauth_issuer=$issuer/.well-known/openid-configuration oauth_scope='' oauth_client_id=f02c6361-0635";
 
 # Misbehaving validators must fail shut.
-$bgconn->query_safe("ALTER SYSTEM SET oauth_validator.authn_id TO ''");
+$bgconn->do("ALTER SYSTEM SET oauth_validator.authn_id TO ''");
 $node->reload;
 $log_start =
   $node->wait_for_log(qr/reloading configuration files/, $log_start);
@@ -562,15 +563,15 @@ $node->connect_fails(
 	expected_stderr => qr/OAuth bearer authentication failed/,
 	log_like => [
 		qr/connection authenticated: identity=""/,
-		qr/FATAL:\s+OAuth bearer authentication failed/,
+		qr/FATAL: ( [A-Z0-9]+:)? OAuth bearer authentication failed/,
 		qr/DETAIL:\s+Validator provided no identity/,
 	]);
 
 # Even if a validator authenticates the user, if the token isn't considered
 # valid, the connection fails.
-$bgconn->query_safe(
+$bgconn->do(
 	"ALTER SYSTEM SET oauth_validator.authn_id TO 'test\@example.org'");
-$bgconn->query_safe(
+$bgconn->do(
 	"ALTER SYSTEM SET oauth_validator.authorize_tokens TO false");
 $node->reload;
 $log_start =
@@ -582,7 +583,7 @@ $node->connect_fails(
 	expected_stderr => qr/OAuth bearer authentication failed/,
 	log_like => [
 		qr/connection authenticated: identity="test\@example\.org"/,
-		qr/FATAL:\s+OAuth bearer authentication failed/,
+		qr/FATAL: ( [A-Z0-9]+:)? OAuth bearer authentication failed/,
 		qr/DETAIL:\s+Validator failed to authorize the provided token/,
 	]);
 
@@ -664,8 +665,8 @@ local all testparam oauth issuer="$issuer" scope="" delegate_ident_mapping=1
 });
 
 # To start, have the validator use the role names as authn IDs.
-$bgconn->query_safe("ALTER SYSTEM RESET oauth_validator.authn_id");
-$bgconn->query_safe("ALTER SYSTEM RESET oauth_validator.authorize_tokens");
+$bgconn->do("ALTER SYSTEM RESET oauth_validator.authn_id");
+$bgconn->do("ALTER SYSTEM RESET oauth_validator.authorize_tokens");
 
 $node->reload;
 $log_start =
@@ -682,7 +683,7 @@ $node->connect_fails(
 	expected_stderr => qr/OAuth bearer authentication failed/);
 
 # Have the validator identify the end user as user@example.com.
-$bgconn->query_safe(
+$bgconn->do(
 	"ALTER SYSTEM SET oauth_validator.authn_id TO 'user\@example.com'");
 $node->reload;
 $log_start =
@@ -706,7 +707,7 @@ $node->connect_ok(
 	expected_stderr =>
 	  qr@Visit https://example\.com/ and enter the code: postgresuser@);
 
-$bgconn->query_safe("ALTER SYSTEM RESET oauth_validator.authn_id");
+$bgconn->do("ALTER SYSTEM RESET oauth_validator.authn_id");
 $node->reload;
 $log_start =
   $node->wait_for_log(qr/reloading configuration files/, $log_start);
@@ -829,7 +830,7 @@ $user = "testalt";
 $node->connect_fails(
 	"user=$user dbname=postgres oauth_issuer=$issuer/.well-known/oauth-authorization-server/alternate oauth_client_id=f02c6361-0636",
 	"fail_validator is used for $user",
-	expected_stderr => qr/FATAL:\s+fail_validator: sentinel error/);
+	expected_stderr => qr/FATAL: ( [A-Z0-9]+:)? fail_validator: sentinel error/);
 
 #
 # Test ABI compatibility magic marker
@@ -849,7 +850,7 @@ $node->connect_fails(
 	"user=test dbname=postgres oauth_issuer=$issuer/.well-known/oauth-authorization-server/alternate oauth_client_id=f02c6361-0636",
 	"magic_validator is used for $user",
 	expected_stderr =>
-	  qr/FATAL:\s+OAuth validator module "magic_validator": magic number mismatch/
+	  qr/FATAL: ( [A-Z0-9]+:)? OAuth validator module "magic_validator": magic number mismatch/
 );
 $node->stop;
 
diff --git a/src/test/modules/test_aio/t/001_aio.pl b/src/test/modules/test_aio/t/001_aio.pl
index 63cadd64c15..bf946801601 100644
--- a/src/test/modules/test_aio/t/001_aio.pl
+++ b/src/test/modules/test_aio/t/001_aio.pl
@@ -4,6 +4,7 @@ use strict;
 use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -62,19 +63,19 @@ sub psql_like
 {
 	local $Test::Builder::Level = $Test::Builder::Level + 1;
 	my $io_method = shift;
-	my $psql = shift;
+	my $session = shift;
 	my $name = shift;
 	my $sql = shift;
 	my $expected_stdout = shift;
 	my $expected_stderr = shift;
-	my ($cmdret, $output);
 
-	($output, $cmdret) = $psql->query($sql);
+	my $res = $session->query($sql);
+	my $output = $res->{psqlout};
 
 	like($output, $expected_stdout, "$io_method: $name: expected stdout");
-	like($psql->{stderr}, $expected_stderr,
+	like($session->get_stderr(), $expected_stderr,
 		"$io_method: $name: expected stderr");
-	$psql->{stderr} = '';
+	$session->clear_stderr();
 
 	return $output;
 }
@@ -87,17 +88,15 @@ sub query_wait_block
 	local $Test::Builder::Level = $Test::Builder::Level + 1;
 	my $io_method = shift;
 	my $node = shift;
-	my $psql = shift;
+	my $session = shift;
 	my $name = shift;
 	my $sql = shift;
 	my $waitfor = shift;
 	my $wait_current_session = shift;
 
-	my $pid = $psql->query_safe('SELECT pg_backend_pid()');
+	my $pid = $session->backend_pid();
 
-	$psql->{stdin} .= qq($sql;\n);
-	$psql->{run}->pump_nb();
-	note "issued sql: $sql;\n";
+	$session->do_async($sql);
 	ok(1, "$io_method: $name: issued sql");
 
 	my $waitquery;
@@ -163,7 +162,7 @@ sub test_handle
 	my $io_method = shift;
 	my $node = shift;
 
-	my $psql = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql = PostgreSQL::Test::Session->new(node => $node);
 
 	# leak warning: implicit xact
 	psql_like(
@@ -269,7 +268,7 @@ sub test_batchmode
 	my $io_method = shift;
 	my $node = shift;
 
-	my $psql = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql = PostgreSQL::Test::Session->new(node => $node);
 
 	# In a build with RELCACHE_FORCE_RELEASE and CATCACHE_FORCE_RELEASE, just
 	# using SELECT batch_start() causes spurious test failures, because the
@@ -329,7 +328,7 @@ sub test_io_error
 	my $node = shift;
 	my ($ret, $output);
 
-	my $psql = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql = PostgreSQL::Test::Session->new(node => $node);
 
 	$psql->query_safe(
 		qq(
@@ -381,8 +380,8 @@ sub test_startwait_io
 	my $node = shift;
 	my ($ret, $output);
 
-	my $psql_a = $node->background_psql('postgres', on_error_stop => 0);
-	my $psql_b = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql_a = PostgreSQL::Test::Session->new(node => $node);
+	my $psql_b = PostgreSQL::Test::Session->new(node => $node);
 
 
 	### Verify behavior for normal tables
@@ -441,7 +440,7 @@ sub test_startwait_io
 
 
 	# Because the IO was terminated, but not marked as valid, second session should get the right to start io
-	pump_until($psql_b->{run}, $psql_b->{timeout}, \$psql_b->{stdout}, qr/t/);
+	$psql_b->wait_for_async_pattern(qr/t/);
 	ok(1, "$io_method: blocking start buffer io, can start io");
 
 	# terminate the IO again
@@ -479,7 +478,7 @@ sub test_startwait_io
 		qr/^$/);
 
 	# Because the IO was terminated, and marked as valid, second session should complete but not need io
-	pump_until($psql_b->{run}, $psql_b->{timeout}, \$psql_b->{stdout}, qr/f/);
+	$psql_b->wait_for_async_pattern(qr/f/);
 	ok(1, "$io_method: blocking start buffer io, no need to start io");
 
 	# buffer is valid now, make it invalid again
@@ -558,8 +557,8 @@ sub test_complete_foreign
 	my $node = shift;
 	my ($ret, $output);
 
-	my $psql_a = $node->background_psql('postgres', on_error_stop => 0);
-	my $psql_b = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql_a = PostgreSQL::Test::Session->new(node => $node);
+	my $psql_b = PostgreSQL::Test::Session->new(node => $node);
 
 	# Issue IO without waiting for completion, then sleep
 	$psql_a->query_safe(
@@ -628,7 +627,7 @@ sub test_close_fd
 	my $node = shift;
 	my ($ret, $output);
 
-	my $psql = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql = PostgreSQL::Test::Session->new(node => $node);
 
 	psql_like(
 		$io_method,
@@ -678,7 +677,7 @@ sub test_inject
 	my $node = shift;
 	my ($ret, $output);
 
-	my $psql = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql = PostgreSQL::Test::Session->new(node => $node);
 
 	# injected what we'd expect
 	$psql->query_safe(qq(SELECT inj_io_short_read_attach(8192);));
@@ -812,7 +811,7 @@ sub test_inject_worker
 	my $node = shift;
 	my ($ret, $output);
 
-	my $psql = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql = PostgreSQL::Test::Session->new(node => $node);
 
 	# trigger a failure to reopen, should error out, but should recover
 	$psql->query_safe(
@@ -849,7 +848,7 @@ sub test_invalidate
 	my $io_method = shift;
 	my $node = shift;
 
-	my $psql = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql = PostgreSQL::Test::Session->new(node => $node);
 
 	foreach my $persistency (qw(normal unlogged temporary))
 	{
@@ -907,8 +906,8 @@ sub test_zero
 	my $io_method = shift;
 	my $node = shift;
 
-	my $psql_a = $node->background_psql('postgres', on_error_stop => 0);
-	my $psql_b = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql_a = PostgreSQL::Test::Session->new(node => $node);
+	my $psql_b = PostgreSQL::Test::Session->new(node => $node);
 
 	foreach my $persistency (qw(normal temporary))
 	{
@@ -933,7 +932,7 @@ SELECT modify_rel_block('tbl_zero', 0, corrupt_header=>true);
 			qq(
 SELECT read_rel_block_ll('tbl_zero', 0, zero_on_error=>false)),
 			qr/^$/,
-			qr/^psql:<stdin>:\d+: ERROR:  invalid page in block 0 of relation "base\/.*\/.*$/
+			qr/^(?:psql:<stdin>:\d+: )?ERROR:  invalid page in block 0 of relation "base\/.*\/.*$/
 		);
 
 		# Check that page validity errors are zeroed
@@ -944,7 +943,7 @@ SELECT read_rel_block_ll('tbl_zero', 0, zero_on_error=>false)),
 			qq(
 SELECT read_rel_block_ll('tbl_zero', 0, zero_on_error=>true)),
 			qr/^$/,
-			qr/^psql:<stdin>:\d+: WARNING:  invalid page in block 0 of relation "base\/.*\/.*"; zeroing out page$/
+			qr/^(?:psql:<stdin>:\d+: )?WARNING:  invalid page in block 0 of relation "base\/.*\/.*"; zeroing out page$/
 		);
 
 		# And that once the corruption is fixed, we can read again
@@ -952,7 +951,7 @@ SELECT read_rel_block_ll('tbl_zero', 0, zero_on_error=>true)),
 			qq(
 SELECT modify_rel_block('tbl_zero', 0, zero=>true);
 ));
-		$psql_a->{stderr} = '';
+		$psql_a->clear_stderr();
 
 		psql_like(
 			$io_method,
@@ -975,7 +974,7 @@ SELECT modify_rel_block('tbl_zero', 3, corrupt_header=>true);
 			"$persistency: test zeroing of invalid block 3",
 			qq(SELECT read_rel_block_ll('tbl_zero', 3, zero_on_error=>true);),
 			qr/^$/,
-			qr/^psql:<stdin>:\d+: WARNING:  invalid page in block 3 of relation "base\/.*\/.*"; zeroing out page$/
+			qr/^(?:psql:<stdin>:\d+: )?WARNING:  invalid page in block 3 of relation "base\/.*\/.*"; zeroing out page$/
 		);
 
 
@@ -992,7 +991,7 @@ SELECT modify_rel_block('tbl_zero', 3, corrupt_header=>true);
 			"$persistency: test reading of invalid block 2,3 in larger read",
 			qq(SELECT read_rel_block_ll('tbl_zero', 1, nblocks=>4, zero_on_error=>false)),
 			qr/^$/,
-			qr/^psql:<stdin>:\d+: ERROR:  2 invalid pages among blocks 1..4 of relation "base\/.*\/.*\nDETAIL:  Block 2 held the first invalid page\.\nHINT:[^\n]+$/
+			qr/^(?:psql:<stdin>:\d+: )?ERROR:  2 invalid pages among blocks 1..4 of relation "base\/.*\/.*\nDETAIL:  Block 2 held the first invalid page\.\nHINT:[^\n]+$/
 		);
 
 		# Then test zeroing via ZERO_ON_ERROR flag
@@ -1002,7 +1001,7 @@ SELECT modify_rel_block('tbl_zero', 3, corrupt_header=>true);
 			"$persistency: test zeroing of invalid block 2,3 in larger read, ZERO_ON_ERROR",
 			qq(SELECT read_rel_block_ll('tbl_zero', 1, nblocks=>4, zero_on_error=>true)),
 			qr/^$/,
-			qr/^psql:<stdin>:\d+: WARNING:  zeroing out 2 invalid pages among blocks 1..4 of relation "base\/.*\/.*\nDETAIL:  Block 2 held the first zeroed page\.\nHINT:[^\n]+$/
+			qr/^(?:psql:<stdin>:\d+: )?WARNING:  zeroing out 2 invalid pages among blocks 1..4 of relation "base\/.*\/.*\nDETAIL:  Block 2 held the first zeroed page\.\nHINT:[^\n]+$/
 		);
 
 		# Then test zeroing via zero_damaged_pages
@@ -1017,7 +1016,7 @@ SELECT read_rel_block_ll('tbl_zero', 1, nblocks=>4, zero_on_error=>false)
 COMMIT;
 ),
 			qr/^$/,
-			qr/^psql:<stdin>:\d+: WARNING:  zeroing out 2 invalid pages among blocks 1..4 of relation "base\/.*\/.*\nDETAIL:  Block 2 held the first zeroed page\.\nHINT:[^\n]+$/
+			qr/^(?:psql:<stdin>:\d+: )?WARNING:  zeroing out 2 invalid pages among blocks 1..4 of relation "base\/.*\/.*\nDETAIL:  Block 2 held the first zeroed page\.\nHINT:[^\n]+$/
 		);
 
 		$psql_a->query_safe(qq(COMMIT));
@@ -1030,7 +1029,7 @@ SELECT invalidate_rel_block('tbl_zero', g.i)
 FROM generate_series(0, 15) g(i);
 SELECT modify_rel_block('tbl_zero', 3, zero=>true);
 ));
-		$psql_a->{stderr} = '';
+		$psql_a->clear_stderr();
 
 		psql_like(
 			$io_method,
@@ -1039,7 +1038,7 @@ SELECT modify_rel_block('tbl_zero', 3, zero=>true);
 			qq(
 SELECT count(*) FROM tbl_zero),
 			qr/^$/,
-			qr/^psql:<stdin>:\d+: ERROR:  invalid page in block 2 of relation "base\/.*\/.*$/
+			qr/^(?:psql:<stdin>:\d+: )?ERROR:  invalid page in block 2 of relation "base\/.*\/.*$/
 		);
 
 		# Verify that bufmgr.c IO zeroes out pages with page validity errors
@@ -1054,7 +1053,7 @@ SELECT count(*) FROM tbl_zero;
 COMMIT;
 ),
 			qr/^\d+$/,
-			qr/^psql:<stdin>:\d+: WARNING:  invalid page in block 2 of relation "base\/.*\/.*$/
+			qr/^(?:psql:<stdin>:\d+: )?WARNING:  invalid page in block 2 of relation "base\/.*\/.*$/
 		);
 
 		# Check that warnings/errors about page validity in an IO started by
@@ -1093,7 +1092,7 @@ DROP TABLE tbl_zero;
 ));
 	}
 
-	$psql_a->{stderr} = '';
+	$psql_a->clear_stderr();
 
 	$psql_a->quit();
 	$psql_b->quit();
@@ -1105,19 +1104,17 @@ sub test_checksum
 	my $io_method = shift;
 	my $node = shift;
 
-	my $psql_a = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql_a = PostgreSQL::Test::Session->new(node => $node);
 
-	$psql_a->query_safe(
-		qq(
-CREATE TABLE tbl_normal(id int) WITH (AUTOVACUUM_ENABLED = false);
-INSERT INTO tbl_normal SELECT generate_series(1, 5000);
-SELECT modify_rel_block('tbl_normal', 3, corrupt_checksum=>true);
-
-CREATE TEMPORARY TABLE tbl_temp(id int) WITH (AUTOVACUUM_ENABLED = false);
-INSERT INTO tbl_temp SELECT generate_series(1, 5000);
-SELECT modify_rel_block('tbl_temp', 3, corrupt_checksum=>true);
-SELECT modify_rel_block('tbl_temp', 4, corrupt_checksum=>true);
-));
+	# Split multi-statement query into separate calls to match psql behavior
+	# where errors in one statement don't prevent subsequent statements
+	$psql_a->query_safe(qq(CREATE TABLE tbl_normal(id int) WITH (AUTOVACUUM_ENABLED = false)));
+	$psql_a->query_safe(qq(INSERT INTO tbl_normal SELECT generate_series(1, 5000)));
+	$psql_a->query_safe(qq(SELECT modify_rel_block('tbl_normal', 3, corrupt_checksum=>true)));
+	$psql_a->query_safe(qq(CREATE TEMPORARY TABLE tbl_temp(id int) WITH (AUTOVACUUM_ENABLED = false)));
+	$psql_a->query_safe(qq(INSERT INTO tbl_temp SELECT generate_series(1, 5000)));
+	$psql_a->query_safe(qq(SELECT modify_rel_block('tbl_temp', 3, corrupt_checksum=>true)));
+	$psql_a->query_safe(qq(SELECT modify_rel_block('tbl_temp', 4, corrupt_checksum=>true)));
 
 	# To be able to test checksum failures on shared rels we need a shared rel
 	# with invalid pages - which is a bit scary. pg_shseclabel seems like a
@@ -1140,7 +1137,7 @@ SELECT modify_rel_block('pg_shseclabel', 3, corrupt_checksum=>true);
 		qq(
 SELECT read_rel_block_ll('tbl_normal', 3, nblocks=>1, zero_on_error=>false);),
 		qr/^$/,
-		qr/^psql:<stdin>:\d+: ERROR:  invalid page in block 3 of relation "base\/\d+\/\d+"$/
+		qr/^(?:psql:<stdin>:\d+: )?ERROR:  invalid page in block 3 of relation "base\/\d+\/\d+"$/
 	);
 
 	my ($cs_count_after, $cs_ts_after) =
@@ -1162,7 +1159,7 @@ SELECT read_rel_block_ll('tbl_normal', 3, nblocks=>1, zero_on_error=>false);),
 		qq(
 SELECT read_rel_block_ll('tbl_temp', 4, nblocks=>2, zero_on_error=>false);),
 		qr/^$/,
-		qr/^psql:<stdin>:\d+: ERROR:  invalid page in block 4 of relation "base\/\d+\/t\d+_\d+"$/
+		qr/^(?:psql:<stdin>:\d+: )?ERROR:  invalid page in block 4 of relation "base\/\d+\/t\d+_\d+"$/
 	);
 
 	($cs_count_after, $cs_ts_after) = checksum_failures($psql_a, 'postgres');
@@ -1183,7 +1180,7 @@ SELECT read_rel_block_ll('tbl_temp', 4, nblocks=>2, zero_on_error=>false);),
 		qq(
 SELECT read_rel_block_ll('pg_shseclabel', 2, nblocks=>2, zero_on_error=>false);),
 		qr/^$/,
-		qr/^psql:<stdin>:\d+: ERROR:  2 invalid pages among blocks 2..3 of relation "global\/\d+"\nDETAIL:  Block 2 held the first invalid page\.\nHINT:[^\n]+$/
+		qr/^(?:psql:<stdin>:\d+: )?ERROR:  2 invalid pages among blocks 2..3 of relation "global\/\d+"\nDETAIL:  Block 2 held the first invalid page\.\nHINT:[^\n]+$/
 	);
 
 	($cs_count_after, $cs_ts_after) = checksum_failures($psql_a);
@@ -1201,7 +1198,7 @@ SELECT read_rel_block_ll('pg_shseclabel', 2, nblocks=>2, zero_on_error=>false);)
 SELECT modify_rel_block('pg_shseclabel', 1, zero=>true);
 DROP TABLE tbl_normal;
 ));
-	$psql_a->{stderr} = '';
+	$psql_a->clear_stderr();
 
 	$psql_a->quit();
 }
@@ -1214,7 +1211,7 @@ sub test_checksum_createdb
 	my $io_method = shift;
 	my $node = shift;
 
-	my $psql = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql = PostgreSQL::Test::Session->new(node => $node);
 
 	$node->safe_psql('postgres',
 		'CREATE DATABASE regression_createdb_source');
@@ -1248,7 +1245,7 @@ STRATEGY wal_log;
 		"create database w/ wal strategy, invalid source",
 		$createdb_sql,
 		qr/^$/,
-		qr/psql:<stdin>:\d+: ERROR:  invalid page in block 1 of relation "base\/\d+\/\d+"$/
+		qr/^(?:psql:<stdin>:\d+: )?ERROR:  invalid page in block 1 of relation "base\/\d+\/\d+"$/
 	);
 	my ($cs_count_after, $cs_ts_after) =
 	  checksum_failures($psql, 'regression_createdb_source');
@@ -1277,7 +1274,7 @@ sub test_ignore_checksum
 	my $io_method = shift;
 	my $node = shift;
 
-	my $psql = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql = PostgreSQL::Test::Session->new(node => $node);
 
 	# Test setup
 	$psql->query_safe(
@@ -1342,7 +1339,7 @@ SELECT modify_rel_block('tbl_cs_fail', 4, corrupt_header=>true);
 		qq(
 SELECT read_rel_block_ll('tbl_cs_fail', 3, nblocks=>1, zero_on_error=>false);),
 		qr/^$/,
-		qr/^psql:<stdin>:\d+: WARNING:  ignoring checksum failure in block 3/
+		qr/^(?:psql:<stdin>:\d+: )?WARNING:  ignoring checksum failure in block 3/
 	);
 
 	# Check that the log contains a LOG message about the failure
@@ -1357,7 +1354,7 @@ SELECT read_rel_block_ll('tbl_cs_fail', 3, nblocks=>1, zero_on_error=>false);),
 		qq(
 SELECT read_rel_block_ll('tbl_cs_fail', 2, nblocks=>3, zero_on_error=>false);),
 		qr/^$/,
-		qr/^psql:<stdin>:\d+: ERROR:  invalid page in block 4 of relation "base\/\d+\/\d+"$/
+		qr/^(?:psql:<stdin>:\d+: )?ERROR:  invalid page in block 4 of relation "base\/\d+\/\d+"$/
 	);
 
 	# Test multi-block read with different problems in different blocks
@@ -1369,7 +1366,7 @@ SELECT modify_rel_block('tbl_cs_fail', 3, corrupt_checksum=>true, corrupt_header
 SELECT modify_rel_block('tbl_cs_fail', 4, corrupt_header=>true);
 SELECT modify_rel_block('tbl_cs_fail', 5, corrupt_header=>true);
 ));
-	$psql->{stderr} = '';
+	$psql->clear_stderr();
 
 	$log_location = -s $node->logfile;
 	psql_like(
@@ -1379,7 +1376,7 @@ SELECT modify_rel_block('tbl_cs_fail', 5, corrupt_header=>true);
 		qq(
 SELECT read_rel_block_ll('tbl_cs_fail', 1, nblocks=>5, zero_on_error=>true);),
 		qr/^$/,
-		qr/^psql:<stdin>:\d+: WARNING:  zeroing 3 page\(s\) and ignoring 2 checksum failure\(s\) among blocks 1..5 of relation "/
+		qr/^(?:psql:<stdin>:\d+: )?WARNING:  zeroing 3 page\(s\) and ignoring 2 checksum failure\(s\) among blocks 1..5 of relation "/
 	);
 
 
@@ -1412,7 +1409,7 @@ SELECT read_rel_block_ll('tbl_cs_fail', 1, nblocks=>5, zero_on_error=>true);),
 		qq(
 SELECT modify_rel_block('tbl_cs_fail', 3, corrupt_checksum=>true, corrupt_header=>true);
 ));
-	$psql->{stderr} = '';
+	$psql->clear_stderr();
 
 	psql_like(
 		$io_method,
@@ -1421,7 +1418,7 @@ SELECT modify_rel_block('tbl_cs_fail', 3, corrupt_checksum=>true, corrupt_header
 		qq(
 SELECT read_rel_block_ll('tbl_cs_fail', 3, nblocks=>1, zero_on_error=>false);),
 		qr/^$/,
-		qr/^psql:<stdin>:\d+: ERROR:  invalid page in block 3 of relation "/);
+		qr/^(?:psql:<stdin>:\d+: )?ERROR:  invalid page in block 3 of relation "/);
 
 	psql_like(
 		$io_method,
@@ -1430,7 +1427,7 @@ SELECT read_rel_block_ll('tbl_cs_fail', 3, nblocks=>1, zero_on_error=>false);),
 		qq(
 SELECT read_rel_block_ll('tbl_cs_fail', 3, nblocks=>1, zero_on_error=>true);),
 		qr/^$/,
-		qr/^psql:<stdin>:\d+: WARNING:  invalid page in block 3 of relation "base\/.*"; zeroing out page/
+		qr/^(?:psql:<stdin>:\d+: )?WARNING:  invalid page in block 3 of relation "base\/.*"; zeroing out page/
 	);
 
 
@@ -1446,8 +1443,8 @@ sub test_read_buffers
 	my ($ret, $output);
 	my $table;
 
-	my $psql_a = $node->background_psql('postgres', on_error_stop => 0);
-	my $psql_b = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql_a = PostgreSQL::Test::Session->new(node => $node);
+	my $psql_b = PostgreSQL::Test::Session->new(node => $node);
 
 	$psql_a->query_safe(
 		qq(
@@ -1631,7 +1628,7 @@ INSERT INTO tmp_ok SELECT generate_series(1, 5000);
 		$psql_a->query_safe(qq|SELECT evict_rel('$table')|);
 
 		my $buf_id =
-		  $psql_b->query_safe(qq|SELECT buffer_create_toy('$table', 3)|);
+		  $psql_b->query_oneval(qq|SELECT buffer_create_toy('$table', 3)|);
 		$psql_b->query_safe(
 			qq|SELECT buffer_call_start_io($buf_id, for_input=>true, wait=>true)|
 		);
@@ -1648,16 +1645,16 @@ INSERT INTO tmp_ok SELECT generate_series(1, 5000);
 			qq|SELECT buffer_call_terminate_io($buf_id, for_input=>true, succeed=>false, io_error=>false, release_aio=>false)|
 		);
 		# Because no IO wref was assigned, block 3 should not report foreign IO
-		pump_until($psql_a->{run}, $psql_a->{timeout}, \$psql_a->{stdout},
-			qr/0\|1\|t\|f\|2\n2\|3\|t\|f\|3/);
-		ok(1,
+		like(
+			$psql_a->wait_for_async_pattern(qr/0\|1\|t\|f\|2\n2\|3\|t\|f\|3/),
+			qr/0\|1\|t\|f\|2\n2\|3\|t\|f\|3/,
 			"$io_method: $persistency: IO was split due to concurrent failed IO"
 		);
 
 		# Same as before, except the concurrent IO succeeds this time
 		$psql_a->query_safe(qq|SELECT evict_rel('$table')|);
 		$buf_id =
-		  $psql_b->query_safe(qq|SELECT buffer_create_toy('$table', 3)|);
+		  $psql_b->query_oneval(qq|SELECT buffer_create_toy('$table', 3)|);
 		$psql_b->query_safe(
 			qq|SELECT buffer_call_start_io($buf_id, for_input=>true, wait=>true)|
 		);
@@ -1674,9 +1671,10 @@ INSERT INTO tmp_ok SELECT generate_series(1, 5000);
 			qq|SELECT buffer_call_terminate_io($buf_id, for_input=>true, succeed=>true, io_error=>false, release_aio=>false)|
 		);
 		# Because no IO wref was assigned, block 3 should not report foreign IO
-		pump_until($psql_a->{run}, $psql_a->{timeout}, \$psql_a->{stdout},
-			qr/0\|1\|t\|f\|2\n2\|3\|f\|f\|1\n3\|4\|t\|f\|2/);
-		ok(1,
+		like(
+			$psql_a->wait_for_async_pattern(
+				qr/0\|1\|t\|f\|2\n2\|3\|f\|f\|1\n3\|4\|t\|f\|2/),
+			qr/0\|1\|t\|f\|2\n2\|3\|f\|f\|1\n3\|4\|t\|f\|2/,
 			"$io_method: $persistency: IO was split due to concurrent successful IO"
 		);
 	}
@@ -1692,9 +1690,9 @@ sub test_read_buffers_inject
 	my $io_method = shift;
 	my $node = shift;
 
-	my $psql_a = $node->background_psql('postgres', on_error_stop => 0);
-	my $psql_b = $node->background_psql('postgres', on_error_stop => 0);
-	my $psql_c = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql_a = PostgreSQL::Test::Session->new(node => $node);
+	my $psql_b = PostgreSQL::Test::Session->new(node => $node);
+	my $psql_c = PostgreSQL::Test::Session->new(node => $node);
 
 	my $expected;
 
@@ -1763,12 +1761,13 @@ sub test_read_buffers_inject
 		# return for something with misses in sync mode.
 		$expected = qr/0\|1\|t\|f\|4/;
 	}
-	pump_until($psql_a->{run}, $psql_a->{timeout}, \$psql_a->{stdout},
-		$expected);
-	ok(1,
+	like($psql_a->wait_for_async_pattern($expected), $expected,
 		"$io_method: $persistency: read 1-3, blocked on in-progress 1, see expected result"
 	);
-	$psql_a->{stdout} = '';
+
+	# B's low-level read has completed now that C released it; drain its
+	# result before B is reused below.
+	$psql_b->wait_for_completion;
 
 
 	###
@@ -1829,12 +1828,12 @@ read_buffers('$table', 0, 4)|,
 		# return for something with misses in sync mode.
 		$expected = qr/0\|0\|t\|f\|4/;
 	}
-	pump_until($psql_a->{run}, $psql_a->{timeout}, \$psql_a->{stdout},
-		$expected);
-	ok(1,
+	like($psql_a->wait_for_async_pattern($expected), $expected,
 		"$io_method: $persistency: read 0-3, blocked on in-progress 2+3, see expected result"
 	);
-	$psql_a->{stdout} = '';
+
+	# Drain B's now-completed low-level read before closing.
+	$psql_b->wait_for_completion;
 
 
 	$psql_a->quit();
diff --git a/src/test/modules/test_aio/t/004_read_stream.pl b/src/test/modules/test_aio/t/004_read_stream.pl
index 32311c07ac0..782b62c452f 100644
--- a/src/test/modules/test_aio/t/004_read_stream.pl
+++ b/src/test/modules/test_aio/t/004_read_stream.pl
@@ -5,6 +5,7 @@ use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
+use PostgreSQL::Test::Session;
 use Test::More;
 
 use FindBin;
@@ -60,7 +61,7 @@ sub test_repeated_blocks
 	my $io_method = shift;
 	my $node = shift;
 
-	my $psql = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql = PostgreSQL::Test::Session->new(node => $node);
 
 	# Preventing larger reads makes testing easier
 	$psql->query_safe(qq/SET io_combine_limit = 1/);
@@ -111,7 +112,7 @@ sub test_repeated_blocks
 		   ARRAY[0, 2, 2, 4, 4]);/);
 	ok(1, "$io_method: temp stream hitting the same block repeatedly");
 
-	$psql->quit();
+	$psql->close();
 }
 
 
@@ -120,10 +121,10 @@ sub test_inject_foreign
 	my $io_method = shift;
 	my $node = shift;
 
-	my $psql_a = $node->background_psql('postgres', on_error_stop => 0);
-	my $psql_b = $node->background_psql('postgres', on_error_stop => 0);
+	my $psql_a = PostgreSQL::Test::Session->new(node => $node);
+	my $psql_b = PostgreSQL::Test::Session->new(node => $node);
 
-	my $pid_a = $psql_a->query_safe(qq/SELECT pg_backend_pid();/);
+	my $pid_a = $psql_a->query_oneval(qq/SELECT pg_backend_pid();/);
 
 
 	###
@@ -136,9 +137,8 @@ sub test_inject_foreign
 		qq/SELECT inj_io_completion_wait(pid=>pg_backend_pid(),
 		   relfilenode=>pg_relation_filenode('largeish'));/);
 
-	$psql_b->{stdin} .= qq/SELECT read_rel_block_ll('largeish',
-		blockno=>5, nblocks=>1);\n/;
-	$psql_b->{run}->pump_nb();
+	$psql_b->do_async(qq/SELECT read_rel_block_ll('largeish',
+		blockno=>5, nblocks=>1);/);
 
 	$node->poll_query_until(
 		'postgres', qq/SELECT wait_event FROM pg_stat_activity
@@ -147,9 +147,8 @@ sub test_inject_foreign
 
 	# Block 5 is undergoing IO in session b, so session a will move on to start
 	# a new IO for block 7.
-	$psql_a->{stdin} .= qq/SELECT array_agg(blocknum) FROM
-		read_stream_for_blocks('largeish', ARRAY[0, 2, 5, 7]);\n/;
-	$psql_a->{run}->pump_nb();
+	$psql_a->do_async(qq/SELECT array_agg(blocknum) FROM
+		read_stream_for_blocks('largeish', ARRAY[0, 2, 5, 7]);/);
 
 	$node->poll_query_until('postgres',
 		qq(SELECT wait_event FROM pg_stat_activity WHERE pid = $pid_a),
@@ -157,10 +156,10 @@ sub test_inject_foreign
 
 	$node->safe_psql('postgres', qq/SELECT inj_io_completion_continue()/);
 
-	pump_until(
-		$psql_a->{run}, $psql_a->{timeout},
-		\$psql_a->{stdout}, qr/\{0,2,5,7\}/);
-	$psql_a->{stdout} = '';
+	$psql_a->wait_for_async_pattern(qr/\{0,2,5,7\}/);
+
+	# Drain session b's now-completed low-level read before reusing it.
+	$psql_b->wait_for_completion;
 
 	ok(1,
 		qq/$io_method: read stream encounters succeeding IO by another backend/
@@ -181,9 +180,8 @@ sub test_inject_foreign
 		   pid=>pg_backend_pid(),
 		   relfilenode=>pg_relation_filenode('largeish'));/);
 
-	$psql_b->{stdin} .= qq/SELECT read_rel_block_ll('largeish',
-		blockno=>5, nblocks=>1);\n/;
-	$psql_b->{run}->pump_nb();
+	$psql_b->do_async(qq/SELECT read_rel_block_ll('largeish',
+		blockno=>5, nblocks=>1);/);
 
 	$node->poll_query_until(
 		'postgres',
@@ -191,9 +189,8 @@ sub test_inject_foreign
 		   WHERE wait_event = 'completion_wait';/,
 		'completion_wait');
 
-	$psql_a->{stdin} .= qq/SELECT array_agg(blocknum) FROM
-		read_stream_for_blocks('largeish', ARRAY[0, 2, 5, 7]);\n/;
-	$psql_a->{run}->pump_nb();
+	$psql_a->do_async(qq/SELECT array_agg(blocknum) FROM
+		read_stream_for_blocks('largeish', ARRAY[0, 2, 5, 7]);/);
 
 	$node->poll_query_until('postgres',
 		qq(SELECT wait_event FROM pg_stat_activity WHERE pid = $pid_a),
@@ -201,15 +198,13 @@ sub test_inject_foreign
 
 	$node->safe_psql('postgres', qq/SELECT inj_io_completion_continue()/);
 
-	pump_until(
-		$psql_a->{run}, $psql_a->{timeout},
-		\$psql_a->{stdout}, qr/\{0,2,5,7\}/);
-	$psql_a->{stdout} = '';
+	$psql_a->wait_for_async_pattern(qr/\{0,2,5,7\}/);
 
-	pump_until($psql_b->{run}, $psql_b->{timeout}, \$psql_b->{stderr},
-		qr/ERROR.*could not read blocks 5\.\.5/);
-	ok(1, "$io_method: injected error occurred");
-	$psql_b->{stderr} = '';
+	# Session b's low-level read hits the injected error.
+	my $res_b = $psql_b->get_async_result();
+	like($res_b->{error_message}, qr/ERROR.*could not read blocks 5\.\.5/,
+		"$io_method: injected error occurred");
+	$psql_b->clear_stderr();
 	$psql_b->query_safe(qq/SELECT inj_io_short_read_detach();/);
 
 	ok(1,
@@ -226,9 +221,8 @@ sub test_inject_foreign
 		qq/SELECT inj_io_completion_wait(pid=>pg_backend_pid(),
 		   relfilenode=>pg_relation_filenode('largeish'));/);
 
-	$psql_b->{stdin} .= qq/SELECT read_rel_block_ll('largeish',
-		blockno=>2, nblocks=>3);\n/;
-	$psql_b->{run}->pump_nb();
+	$psql_b->do_async(qq/SELECT read_rel_block_ll('largeish',
+		blockno=>2, nblocks=>3);/);
 
 	$node->poll_query_until(
 		'postgres',
@@ -237,9 +231,8 @@ sub test_inject_foreign
 		'completion_wait');
 
 	# Blocks 2 and 4 are undergoing IO initiated by session b
-	$psql_a->{stdin} .= qq/SELECT array_agg(blocknum) FROM
-		read_stream_for_blocks('largeish', ARRAY[0, 2, 4]);\n/;
-	$psql_a->{run}->pump_nb();
+	$psql_a->do_async(qq/SELECT array_agg(blocknum) FROM
+		read_stream_for_blocks('largeish', ARRAY[0, 2, 4]);/);
 
 	$node->poll_query_until('postgres',
 		qq(SELECT wait_event FROM pg_stat_activity WHERE pid = $pid_a),
@@ -247,15 +240,15 @@ sub test_inject_foreign
 
 	$node->safe_psql('postgres', qq/SELECT inj_io_completion_continue()/);
 
-	pump_until(
-		$psql_a->{run}, $psql_a->{timeout},
-		\$psql_a->{stdout}, qr/\{0,2,4\}/);
-	$psql_a->{stdout} = '';
+	$psql_a->wait_for_async_pattern(qr/\{0,2,4\}/);
+
+	# Drain session b's now-completed low-level read.
+	$psql_b->wait_for_completion;
 
 	ok(1, qq/$io_method: read stream encounters two buffer read in one IO/);
 
-	$psql_a->quit();
-	$psql_b->quit();
+	$psql_a->close();
+	$psql_b->close();
 }
 
 
diff --git a/src/test/modules/test_checksums/t/002_restarts.pl b/src/test/modules/test_checksums/t/002_restarts.pl
index 1aa2c0c65e5..cd9a7314c8a 100644
--- a/src/test/modules/test_checksums/t/002_restarts.pl
+++ b/src/test/modules/test_checksums/t/002_restarts.pl
@@ -8,6 +8,7 @@ use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
+use PostgreSQL::Test::Session;
 use Test::More;
 
 use FindBin;
@@ -44,8 +45,8 @@ SKIP:
 	#
 	# This is a similar test to the synthetic variant in 005_injection.pl
 	# which fakes this scenario.
-	my $bsession = $node->background_psql('postgres');
-	$bsession->query_safe('CREATE TEMPORARY TABLE tt (a integer);');
+	my $bsession = PostgreSQL::Test::Session->new(node => $node);
+	$bsession->do('CREATE TEMPORARY TABLE tt (a integer);');
 
 	# In another session, make sure we can see the blocking temp table but
 	# start processing anyways and check that we are blocked with a proper
@@ -85,7 +86,7 @@ SKIP:
 	# session first since the brief period between closing and stopping might
 	# be enough for checksums to get enabled.
 	$node->stop;
-	$bsession->quit;
+	$bsession->close;
 	$node->start;
 
 	# Ensure the checksums aren't enabled across the restart.  This leaves the
diff --git a/src/test/modules/test_checksums/t/003_standby_restarts.pl b/src/test/modules/test_checksums/t/003_standby_restarts.pl
index bb35ed0b325..67d4e76e7b5 100644
--- a/src/test/modules/test_checksums/t/003_standby_restarts.pl
+++ b/src/test/modules/test_checksums/t/003_standby_restarts.pl
@@ -7,6 +7,7 @@ use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
+use PostgreSQL::Test::Session;
 use Test::More;
 
 use FindBin;
@@ -255,11 +256,11 @@ $node_primary->wait_for_catchup($node_standby, 'replay');
 
 # Open a background psql connection on the primary and inject a barrier to
 # block progress on to keep the state from advancing past inprogress-on
-my $node_primary_bpsql = $node_primary->background_psql('postgres');
-$node_primary_bpsql->query_safe('CREATE TEMPORARY TABLE tt (a integer);');
+my $node_primary_bpsql = PostgreSQL::Test::Session->new(node => $node_primary);
+$node_primary_bpsql->do('CREATE TEMPORARY TABLE tt (a integer);');
 # Also open a background psql connection to the standby to make sure we have
 # an active backend during promotion.
-my $node_standby_bpsql = $node_standby->background_psql('postgres');
+my $node_standby_bpsql = PostgreSQL::Test::Session->new(node => $node_standby);
 
 # Start to enable checksums and wait until both primary and standby have moved
 # to the inprogress-on state.  Processing will block here as the temporary rel
@@ -281,7 +282,11 @@ $result = $node_standby_bpsql->query_safe("SHOW data_checksums;");
 is($result, 'off',
 	'ensure checksums are set to off after promotion during inprogress-on');
 
-$node_standby_bpsql->quit;
+# The primary's session was kept open only to hold the blocking temp table;
+# close it explicitly (its backend is already gone after the crash) so it is
+# not left to be torn down at global destruction.
+$node_primary_bpsql->close;
+$node_standby_bpsql->close;
 $node_standby->stop;
 
 done_testing();
diff --git a/src/test/modules/test_checksums/t/004_offline.pl b/src/test/modules/test_checksums/t/004_offline.pl
index 73c279e75e0..be6b6b6e4c6 100644
--- a/src/test/modules/test_checksums/t/004_offline.pl
+++ b/src/test/modules/test_checksums/t/004_offline.pl
@@ -8,6 +8,7 @@ use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
+use PostgreSQL::Test::Session;
 use Test::More;
 
 use FindBin;
@@ -53,8 +54,8 @@ test_checksum_state($node, 'off');
 # can accomplish this by setting up an interactive psql process which keeps the
 # temporary table created as we enable checksums in another psql process.
 
-my $bsession = $node->background_psql('postgres');
-$bsession->query_safe('CREATE TEMPORARY TABLE tt (a integer);');
+my $bsession = PostgreSQL::Test::Session->new(node => $node);
+$bsession->do('CREATE TEMPORARY TABLE tt (a integer);');
 
 # In another session, make sure we can see the blocking temp table but start
 # processing anyways and check that we are blocked with a proper wait event.
@@ -70,7 +71,7 @@ enable_data_checksums($node, wait => 'inprogress-on');
 # Stop the cluster before exiting the background session since otherwise
 # checksums might have time to get enabled before shutting down the cluster.
 $node->stop('fast');
-$bsession->quit;
+$bsession->close;
 $node->checksum_enable_offline;
 $node->start;
 
diff --git a/src/test/modules/test_misc/t/005_timeouts.pl b/src/test/modules/test_misc/t/005_timeouts.pl
index c16b7dbf5e6..d64a787a9ab 100644
--- a/src/test/modules/test_misc/t/005_timeouts.pl
+++ b/src/test/modules/test_misc/t/005_timeouts.pl
@@ -6,6 +6,7 @@ use warnings FATAL => 'all';
 use locale;
 
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Time::HiRes qw(usleep);
 use Test::More;
@@ -42,24 +43,16 @@ $node->safe_psql('postgres', 'CREATE EXTENSION injection_points;');
 $node->safe_psql('postgres',
 	"SELECT injection_points_attach('transaction-timeout', 'wait');");
 
-my $psql_session = $node->background_psql('postgres');
+my $psql_session = PostgreSQL::Test::Session->new(node => $node);
 
-# The following query will generate a stream of SELECT 1 queries. This is done
-# so to exercise transaction timeout in the presence of short queries.
-# Note: the interval value is parsed with locale-aware strtod()
-$psql_session->query_until(
-	qr/starting_bg_psql/,
-	sprintf(
-		q(\echo starting_bg_psql
-		SET transaction_timeout to '10ms';
-		BEGIN;
-		SELECT 1 \watch %g
-		\q
-), 0.001));
+$psql_session->do("SET transaction_timeout to '10ms';");
+
+$psql_session->do_async("BEGIN; DO ' begin loop PERFORM pg_sleep(0.001); end loop; end ';");
 
 # Wait until the backend enters the timeout injection point. Will get an error
 # here if anything goes wrong.
 $node->wait_for_event('client backend', 'transaction-timeout');
+pass("got transaction timeout event");
 
 my $log_offset = -s $node->logfile;
 
@@ -70,11 +63,9 @@ $node->safe_psql('postgres',
 # Check that the timeout was logged.
 $node->wait_for_log('terminating connection due to transaction timeout',
 	$log_offset);
+pass("got transaction timeout log");
 
-# If we send \q with $psql_session->quit the command can be sent to the session
-# already closed. So \q is in initial script, here we only finish IPC::Run.
-$psql_session->{run}->finish;
-
+$psql_session->close;
 
 #
 # 2. Test of the idle in transaction timeout
@@ -85,10 +76,8 @@ $node->safe_psql('postgres',
 );
 
 # We begin a transaction and the hand on the line
-$psql_session = $node->background_psql('postgres');
-$psql_session->query_until(
-	qr/starting_bg_psql/, q(
-   \echo starting_bg_psql
+$psql_session->reconnect;
+$psql_session->do(q(
    SET idle_in_transaction_session_timeout to '10ms';
    BEGIN;
 ));
@@ -96,6 +85,7 @@ $psql_session->query_until(
 # Wait until the backend enters the timeout injection point.
 $node->wait_for_event('client backend',
 	'idle-in-transaction-session-timeout');
+pass("got idle in transaction timeout event");
 
 $log_offset = -s $node->logfile;
 
@@ -106,8 +96,9 @@ $node->safe_psql('postgres',
 # Check that the timeout was logged.
 $node->wait_for_log(
 	'terminating connection due to idle-in-transaction timeout', $log_offset);
+pass("got idle in transaction timeout log");
 
-ok($psql_session->quit);
+$psql_session->close;
 
 
 #
@@ -117,15 +108,14 @@ $node->safe_psql('postgres',
 	"SELECT injection_points_attach('idle-session-timeout', 'wait');");
 
 # We just initialize the GUC and wait. No transaction is required.
-$psql_session = $node->background_psql('postgres');
-$psql_session->query_until(
-	qr/starting_bg_psql/, q(
-   \echo starting_bg_psql
+$psql_session->reconnect;
+$psql_session->do(q(
    SET idle_session_timeout to '10ms';
 ));
 
 # Wait until the backend enters the timeout injection point.
 $node->wait_for_event('client backend', 'idle-session-timeout');
+pass("got idle session timeout event");
 
 $log_offset = -s $node->logfile;
 
@@ -136,7 +126,8 @@ $node->safe_psql('postgres',
 # Check that the timeout was logged.
 $node->wait_for_log('terminating connection due to idle-session timeout',
 	$log_offset);
+pass("got idle sesion tiemout log");
 
-ok($psql_session->quit);
+$psql_session->close;
 
 done_testing();
diff --git a/src/test/modules/test_misc/t/007_catcache_inval.pl b/src/test/modules/test_misc/t/007_catcache_inval.pl
index 424556261c9..e3b3fd8bae9 100644
--- a/src/test/modules/test_misc/t/007_catcache_inval.pl
+++ b/src/test/modules/test_misc/t/007_catcache_inval.pl
@@ -46,12 +46,12 @@ $node->safe_psql(
     CREATE FUNCTION foofunc(dummy integer) RETURNS integer AS \$\$ SELECT 1; /* $longtext */ \$\$ LANGUAGE SQL
 ]);
 
-my $psql_session = $node->background_psql('postgres');
-my $psql_session2 = $node->background_psql('postgres');
+my $psql_session = PostgreSQL::Test::Session->new(node => $node);
+my $psql_session2 = PostgreSQL::Test::Session->new(node => $node);
 
 # Set injection point in the session, to pause while populating the
 # catcache list
-$psql_session->query_safe(
+$psql_session->do(
 	qq[
     SELECT injection_points_set_local();
     SELECT injection_points_attach('catcache-list-miss-systable-scan-started', 'wait');
@@ -59,10 +59,9 @@ $psql_session->query_safe(
 
 # This pauses on the injection point while populating catcache list
 # for functions with name "foofunc"
-$psql_session->query_until(
-	qr/starting_bg_psql/, q(
-   \echo starting_bg_psql
-   SELECT foofunc(1);
+$psql_session->do_async(
+   q(
+      SELECT foofunc(1);
 ));
 
 # While the first session is building the catcache list, create a new
@@ -83,16 +82,19 @@ $node->safe_psql(
 # trying to exercise here.)
 #
 # The "SELECT foofunc(1)" query will now finish.
-$psql_session2->query_safe(
+$psql_session2->do(
 	qq[
     SELECT injection_points_wakeup('catcache-list-miss-systable-scan-started');
     SELECT injection_points_detach('catcache-list-miss-systable-scan-started');
 ]);
 
 # Test that the new function is visible to the session.
-$psql_session->query_safe("SELECT foofunc();");
+$psql_session->wait_for_completion;
+my $res = $psql_session->query("SELECT foofunc();");
 
-ok($psql_session->quit);
-ok($psql_session2->quit);
+is($res->{status}, 2, "got TUPLES_OK");
+
+$psql_session->close;
+$psql_session2->close;
 
 done_testing();
diff --git a/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl b/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
index 50a0e7db8f7..a7359cb0624 100644
--- a/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
+++ b/src/test/modules/test_misc/t/010_index_concurrently_upsert.pl
@@ -13,6 +13,7 @@ use strict;
 use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 use Time::HiRes qw(usleep);
@@ -51,47 +52,38 @@ ALTER TABLE test.tblexpr SET (parallel_workers=0);
 ############################################################################
 note('Test: REINDEX CONCURRENTLY + UPSERT (wakeup at set-dead phase)');
 
-# Create sessions with on_error_stop => 0 so psql doesn't exit on SQL errors.
-# This allows us to collect stderr and detect errors after the test completes.
-my $s1 = $node->background_psql('postgres', on_error_stop => 0);
-my $s2 = $node->background_psql('postgres', on_error_stop => 0);
-my $s3 = $node->background_psql('postgres', on_error_stop => 0);
+# Create sessions for concurrent operations
+my $s1 = PostgreSQL::Test::Session->new(node => $node);
+my $s2 = PostgreSQL::Test::Session->new(node => $node);
+my $s3 = PostgreSQL::Test::Session->new(node => $node);
 
 # Setup injection points for each session
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 ]);
 
-$s2->query_safe(
+$s2->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
 ]);
 
-$s3->query_safe(
+$s3->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
 ]);
 
 # s3 starts REINDEX (will block on reindex-relation-concurrently-before-set-dead)
-$s3->query_until(
-	qr/starting_reindex/, q[
-\echo starting_reindex
-REINDEX INDEX CONCURRENTLY test.tblpk_pkey;
-]);
+$s3->do_async(q[REINDEX INDEX CONCURRENTLY test.tblpk_pkey;]);
 
 # Wait for s3 to hit injection point
 ok_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
 
 # s1 starts UPSERT (will block on check-exclusion-or-unique-constraint-no-conflict)
-$s1->query_until(
-	qr/starting_upsert_s1/, q[
-\echo starting_upsert_s1
-INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s1->do_async(q[INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 # Wait for s1 to hit injection point
 ok_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
@@ -101,11 +93,7 @@ wakeup_injection_point($node,
 	'reindex-relation-concurrently-before-set-dead');
 
 # s2 starts UPSERT (will block on exec-insert-before-insert-speculative)
-$s2->query_until(
-	qr/starting_upsert_s2/, q[
-\echo starting_upsert_s2
-INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s2->do_async(q[INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 # Wait for s2 to hit injection point
 ok_injection_point($node, 'exec-insert-before-insert-speculative');
@@ -125,51 +113,39 @@ $node->safe_psql('postgres', 'TRUNCATE TABLE test.tblpk');
 ############################################################################
 note('Test: REINDEX CONCURRENTLY + UPSERT (wakeup at swap phase)');
 
-$s1 = $node->background_psql('postgres', on_error_stop => 0);
-$s2 = $node->background_psql('postgres', on_error_stop => 0);
-$s3 = $node->background_psql('postgres', on_error_stop => 0);
+$s1 = PostgreSQL::Test::Session->new(node => $node);
+$s2 = PostgreSQL::Test::Session->new(node => $node);
+$s3 = PostgreSQL::Test::Session->new(node => $node);
 
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 ]);
 
-$s2->query_safe(
+$s2->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
 ]);
 
-$s3->query_safe(
+$s3->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
 ]);
 
-$s3->query_until(
-	qr/starting_reindex/, q[
-\echo starting_reindex
-REINDEX INDEX CONCURRENTLY test.tblpk_pkey;
-]);
+$s3->do_async(q[REINDEX INDEX CONCURRENTLY test.tblpk_pkey;]);
 
 ok_injection_point($node, 'reindex-relation-concurrently-before-swap');
 
-$s1->query_until(
-	qr/starting_upsert_s1/, q[
-\echo starting_upsert_s1
-INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s1->do_async(q[INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
 
 wakeup_injection_point($node, 'reindex-relation-concurrently-before-swap');
 
-$s2->query_until(
-	qr/starting_upsert_s2/, q[
-\echo starting_upsert_s2
-INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s2->do_async(q[INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'exec-insert-before-insert-speculative');
 
@@ -184,50 +160,38 @@ $node->safe_psql('postgres', 'TRUNCATE TABLE test.tblpk');
 ############################################################################
 note('Test: REINDEX CONCURRENTLY + UPSERT (s1 wakes before reindex)');
 
-$s1 = $node->background_psql('postgres', on_error_stop => 0);
-$s2 = $node->background_psql('postgres', on_error_stop => 0);
-$s3 = $node->background_psql('postgres', on_error_stop => 0);
+$s1 = PostgreSQL::Test::Session->new(node => $node);
+$s2 = PostgreSQL::Test::Session->new(node => $node);
+$s3 = PostgreSQL::Test::Session->new(node => $node);
 
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 ]);
 
-$s2->query_safe(
+$s2->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
 ]);
 
-$s3->query_safe(
+$s3->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
 ]);
 
-$s3->query_until(
-	qr/starting_reindex/, q[
-\echo starting_reindex
-REINDEX INDEX CONCURRENTLY test.tblpk_pkey;
-]);
+$s3->do_async(q[REINDEX INDEX CONCURRENTLY test.tblpk_pkey;]);
 
 ok_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
 
-$s1->query_until(
-	qr/starting_upsert_s1/, q[
-\echo starting_upsert_s1
-INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s1->do_async(q[INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
 
 # Start s2 BEFORE waking reindex (key difference from permutation 1)
-$s2->query_until(
-	qr/starting_upsert_s2/, q[
-\echo starting_upsert_s2
-INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s2->do_async(q[INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'exec-insert-before-insert-speculative');
 
@@ -245,52 +209,40 @@ $node->safe_psql('postgres', 'TRUNCATE TABLE test.tblpk');
 ############################################################################
 note('Test: REINDEX + UPSERT ON CONSTRAINT (set-dead phase)');
 
-$s1 = $node->background_psql('postgres', on_error_stop => 0);
-$s2 = $node->background_psql('postgres', on_error_stop => 0);
-$s3 = $node->background_psql('postgres', on_error_stop => 0);
+$s1 = PostgreSQL::Test::Session->new(node => $node);
+$s2 = PostgreSQL::Test::Session->new(node => $node);
+$s3 = PostgreSQL::Test::Session->new(node => $node);
 
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 ]);
 
-$s2->query_safe(
+$s2->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
 ]);
 
-$s3->query_safe(
+$s3->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
 ]);
 
-$s3->query_until(
-	qr/starting_reindex/, q[
-\echo starting_reindex
-REINDEX INDEX CONCURRENTLY test.tblpk_pkey;
-]);
+$s3->do_async(q[REINDEX INDEX CONCURRENTLY test.tblpk_pkey;]);
 
 ok_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
 
-$s1->query_until(
-	qr/starting_upsert_s1/, q[
-\echo starting_upsert_s1
-INSERT INTO test.tblpk VALUES (13, now()) ON CONFLICT ON CONSTRAINT tblpk_pkey DO UPDATE SET updated_at = now();
-]);
+$s1->do_async(q[INSERT INTO test.tblpk VALUES (13, now()) ON CONFLICT ON CONSTRAINT tblpk_pkey DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
 
 wakeup_injection_point($node,
 	'reindex-relation-concurrently-before-set-dead');
 
-$s2->query_until(
-	qr/starting_upsert_s2/, q[
-\echo starting_upsert_s2
-INSERT INTO test.tblpk VALUES (13, now()) ON CONFLICT ON CONSTRAINT tblpk_pkey DO UPDATE SET updated_at = now();
-]);
+$s2->do_async(q[INSERT INTO test.tblpk VALUES (13, now()) ON CONFLICT ON CONSTRAINT tblpk_pkey DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'exec-insert-before-insert-speculative');
 
@@ -305,51 +257,39 @@ $node->safe_psql('postgres', 'TRUNCATE TABLE test.tblpk');
 ############################################################################
 note('Test: REINDEX + UPSERT ON CONSTRAINT (swap phase)');
 
-$s1 = $node->background_psql('postgres', on_error_stop => 0);
-$s2 = $node->background_psql('postgres', on_error_stop => 0);
-$s3 = $node->background_psql('postgres', on_error_stop => 0);
+$s1 = PostgreSQL::Test::Session->new(node => $node);
+$s2 = PostgreSQL::Test::Session->new(node => $node);
+$s3 = PostgreSQL::Test::Session->new(node => $node);
 
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 ]);
 
-$s2->query_safe(
+$s2->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
 ]);
 
-$s3->query_safe(
+$s3->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
 ]);
 
-$s3->query_until(
-	qr/starting_reindex/, q[
-\echo starting_reindex
-REINDEX INDEX CONCURRENTLY test.tblpk_pkey;
-]);
+$s3->do_async(q[REINDEX INDEX CONCURRENTLY test.tblpk_pkey;]);
 
 ok_injection_point($node, 'reindex-relation-concurrently-before-swap');
 
-$s1->query_until(
-	qr/starting_upsert_s1/, q[
-\echo starting_upsert_s1
-INSERT INTO test.tblpk VALUES (13, now()) ON CONFLICT ON CONSTRAINT tblpk_pkey DO UPDATE SET updated_at = now();
-]);
+$s1->do_async(q[INSERT INTO test.tblpk VALUES (13, now()) ON CONFLICT ON CONSTRAINT tblpk_pkey DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
 
 wakeup_injection_point($node, 'reindex-relation-concurrently-before-swap');
 
-$s2->query_until(
-	qr/starting_upsert_s2/, q[
-\echo starting_upsert_s2
-INSERT INTO test.tblpk VALUES (13, now()) ON CONFLICT ON CONSTRAINT tblpk_pkey DO UPDATE SET updated_at = now();
-]);
+$s2->do_async(q[INSERT INTO test.tblpk VALUES (13, now()) ON CONFLICT ON CONSTRAINT tblpk_pkey DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'exec-insert-before-insert-speculative');
 
@@ -364,50 +304,38 @@ $node->safe_psql('postgres', 'TRUNCATE TABLE test.tblpk');
 ############################################################################
 note('Test: REINDEX + UPSERT ON CONSTRAINT (s1 wakes before reindex)');
 
-$s1 = $node->background_psql('postgres', on_error_stop => 0);
-$s2 = $node->background_psql('postgres', on_error_stop => 0);
-$s3 = $node->background_psql('postgres', on_error_stop => 0);
+$s1 = PostgreSQL::Test::Session->new(node => $node);
+$s2 = PostgreSQL::Test::Session->new(node => $node);
+$s3 = PostgreSQL::Test::Session->new(node => $node);
 
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 ]);
 
-$s2->query_safe(
+$s2->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
 ]);
 
-$s3->query_safe(
+$s3->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
 ]);
 
-$s3->query_until(
-	qr/starting_reindex/, q[
-\echo starting_reindex
-REINDEX INDEX CONCURRENTLY test.tblpk_pkey;
-]);
+$s3->do_async(q[REINDEX INDEX CONCURRENTLY test.tblpk_pkey;]);
 
 ok_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
 
-$s1->query_until(
-	qr/starting_upsert_s1/, q[
-\echo starting_upsert_s1
-INSERT INTO test.tblpk VALUES (13, now()) ON CONFLICT ON CONSTRAINT tblpk_pkey DO UPDATE SET updated_at = now();
-]);
+$s1->do_async(q[INSERT INTO test.tblpk VALUES (13, now()) ON CONFLICT ON CONSTRAINT tblpk_pkey DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
 
 # Start s2 BEFORE waking reindex
-$s2->query_until(
-	qr/starting_upsert_s2/, q[
-\echo starting_upsert_s2
-INSERT INTO test.tblpk VALUES (13, now()) ON CONFLICT ON CONSTRAINT tblpk_pkey DO UPDATE SET updated_at = now();
-]);
+$s2->do_async(q[INSERT INTO test.tblpk VALUES (13, now()) ON CONFLICT ON CONSTRAINT tblpk_pkey DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'exec-insert-before-insert-speculative');
 
@@ -425,52 +353,40 @@ $node->safe_psql('postgres', 'TRUNCATE TABLE test.tblpk');
 ############################################################################
 note('Test: REINDEX on partitioned table (set-dead phase)');
 
-$s1 = $node->background_psql('postgres', on_error_stop => 0);
-$s2 = $node->background_psql('postgres', on_error_stop => 0);
-$s3 = $node->background_psql('postgres', on_error_stop => 0);
+$s1 = PostgreSQL::Test::Session->new(node => $node);
+$s2 = PostgreSQL::Test::Session->new(node => $node);
+$s3 = PostgreSQL::Test::Session->new(node => $node);
 
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 ]);
 
-$s2->query_safe(
+$s2->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
 ]);
 
-$s3->query_safe(
+$s3->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
 ]);
 
-$s3->query_until(
-	qr/starting_reindex/, q[
-\echo starting_reindex
-REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
-]);
+$s3->do_async(q[REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;]);
 
 ok_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
 
-$s1->query_until(
-	qr/starting_upsert_s1/, q[
-\echo starting_upsert_s1
-INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s1->do_async(q[INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
 
 wakeup_injection_point($node,
 	'reindex-relation-concurrently-before-set-dead');
 
-$s2->query_until(
-	qr/starting_upsert_s2/, q[
-\echo starting_upsert_s2
-INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s2->do_async(q[INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'exec-insert-before-insert-speculative');
 
@@ -485,51 +401,39 @@ $node->safe_psql('postgres', 'TRUNCATE TABLE test.tblparted');
 ############################################################################
 note('Test: REINDEX on partitioned table (swap phase)');
 
-$s1 = $node->background_psql('postgres', on_error_stop => 0);
-$s2 = $node->background_psql('postgres', on_error_stop => 0);
-$s3 = $node->background_psql('postgres', on_error_stop => 0);
+$s1 = PostgreSQL::Test::Session->new(node => $node);
+$s2 = PostgreSQL::Test::Session->new(node => $node);
+$s3 = PostgreSQL::Test::Session->new(node => $node);
 
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 ]);
 
-$s2->query_safe(
+$s2->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
 ]);
 
-$s3->query_safe(
+$s3->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
 ]);
 
-$s3->query_until(
-	qr/starting_reindex/, q[
-\echo starting_reindex
-REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
-]);
+$s3->do_async(q[REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;]);
 
 ok_injection_point($node, 'reindex-relation-concurrently-before-swap');
 
-$s1->query_until(
-	qr/starting_upsert_s1/, q[
-\echo starting_upsert_s1
-INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s1->do_async(q[INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
 
 wakeup_injection_point($node, 'reindex-relation-concurrently-before-swap');
 
-$s2->query_until(
-	qr/starting_upsert_s2/, q[
-\echo starting_upsert_s2
-INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s2->do_async(q[INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'exec-insert-before-insert-speculative');
 
@@ -544,50 +448,38 @@ $node->safe_psql('postgres', 'TRUNCATE TABLE test.tblparted');
 ############################################################################
 note('Test: REINDEX on partitioned table (s1 wakes before reindex)');
 
-$s1 = $node->background_psql('postgres', on_error_stop => 0);
-$s2 = $node->background_psql('postgres', on_error_stop => 0);
-$s3 = $node->background_psql('postgres', on_error_stop => 0);
+$s1 = PostgreSQL::Test::Session->new(node => $node);
+$s2 = PostgreSQL::Test::Session->new(node => $node);
+$s3 = PostgreSQL::Test::Session->new(node => $node);
 
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 ]);
 
-$s2->query_safe(
+$s2->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
 ]);
 
-$s3->query_safe(
+$s3->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('reindex-relation-concurrently-before-set-dead', 'wait');
 ]);
 
-$s3->query_until(
-	qr/starting_reindex/, q[
-\echo starting_reindex
-REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
-]);
+$s3->do_async(q[REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;]);
 
 ok_injection_point($node, 'reindex-relation-concurrently-before-set-dead');
 
-$s1->query_until(
-	qr/starting_upsert_s1/, q[
-\echo starting_upsert_s1
-INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s1->do_async(q[INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'check-exclusion-or-unique-constraint-no-conflict');
 
 # Start s2 BEFORE waking reindex
-$s2->query_until(
-	qr/starting_upsert_s2/, q[
-\echo starting_upsert_s2
-INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s2->do_async(q[INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'exec-insert-before-insert-speculative');
 
@@ -607,35 +499,27 @@ note(
 	'Test: REINDEX on partitioned table, cache inval between two get_partition_ancestors'
 );
 
-$s1 = $node->background_psql('postgres', on_error_stop => 0);
-$s2 = $node->background_psql('postgres', on_error_stop => 0);
-$s3 = $node->background_psql('postgres', on_error_stop => 0);
+$s1 = PostgreSQL::Test::Session->new(node => $node);
+$s2 = PostgreSQL::Test::Session->new(node => $node);
+$s3 = PostgreSQL::Test::Session->new(node => $node);
 
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('exec-init-partition-after-get-partition-ancestors', 'wait');
 ]);
 
-$s2->query_safe(
+$s2->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('reindex-relation-concurrently-before-swap', 'wait');
 ]);
 
-$s2->query_until(
-	qr/starting_reindex/, q[
-\echo starting_reindex
-REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;
-]);
+$s2->do_async(q[REINDEX INDEX CONCURRENTLY test.tbl_partition_pkey;]);
 
 ok_injection_point($node, 'reindex-relation-concurrently-before-swap');
 
-$s1->query_until(
-	qr/starting_upsert_s1/, q[
-\echo starting_upsert_s1
-INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s1->do_async(q[INSERT INTO test.tblparted VALUES (13, now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node,
 	'exec-init-partition-after-get-partition-ancestors');
@@ -654,26 +538,24 @@ note('Test: CREATE INDEX CONCURRENTLY + UPSERT');
 # Uses invalidate-catalog-snapshot-end to test catalog invalidation
 # during UPSERT
 
-$s1 = $node->background_psql('postgres', on_error_stop => 0);
-$s2 = $node->background_psql('postgres', on_error_stop => 0);
-$s3 = $node->background_psql('postgres', on_error_stop => 0);
+$s1 = PostgreSQL::Test::Session->new(node => $node);
+$s2 = PostgreSQL::Test::Session->new(node => $node);
+$s3 = PostgreSQL::Test::Session->new(node => $node);
 
-my $s1_pid = $s1->query_safe('SELECT pg_backend_pid()');
+# Get the session's backend PID before attaching injection points
+my $s1_pid = $s1->query_oneval('SELECT pg_backend_pid()');
 
 # s1 attaches BOTH injection points - the unique constraint check AND catalog snapshot
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 ]);
 
-$s1->query_until(
-	qr/attaching_injection_point/, q[
-\echo attaching_injection_point
-SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
-]);
-
 # In cases of cache clobbering, s1 may hit the injection point during attach.
+# Start attach asynchronously so we can check if it blocks.
+$s1->do_async(q[SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');]);
+
 # Wait for that session to become idle (attach completed), or wake it up if
 # it becomes stuck on injection point.
 if (!wait_for_idle($node, $s1_pid))
@@ -687,34 +569,28 @@ if (!wait_for_idle($node, $s1_pid))
 		SELECT injection_points_wakeup('invalidate-catalog-snapshot-end');
 	]);
 }
+# Wait for async command to complete
+$s1->wait_for_completion;
 
-$s2->query_safe(
+$s2->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
 ]);
 
-$s3->query_safe(
+$s3->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('define-index-before-set-valid', 'wait');
 ]);
 
 # s3: Start CREATE INDEX CONCURRENTLY (blocks on define-index-before-set-valid)
-$s3->query_until(
-	qr/starting_create_index/, q[
-\echo starting_create_index
-CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tblpk(i);
-]);
+$s3->do_async(q[CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_duplicate ON test.tblpk(i);]);
 
 ok_injection_point($node, 'define-index-before-set-valid');
 
 # s1: Start UPSERT (blocks on invalidate-catalog-snapshot-end)
-$s1->query_until(
-	qr/starting_upsert_s1/, q[
-\echo starting_upsert_s1
-INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s1->do_async(q[INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'invalidate-catalog-snapshot-end');
 
@@ -722,11 +598,7 @@ ok_injection_point($node, 'invalidate-catalog-snapshot-end');
 wakeup_injection_point($node, 'define-index-before-set-valid');
 
 # s2: Start UPSERT (blocks on exec-insert-before-insert-speculative)
-$s2->query_until(
-	qr/starting_upsert_s2/, q[
-\echo starting_upsert_s2
-INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();
-]);
+$s2->do_async(q[INSERT INTO test.tblpk VALUES (13,now()) ON CONFLICT (i) DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'exec-insert-before-insert-speculative');
 
@@ -747,24 +619,20 @@ $node->safe_psql('postgres', 'TRUNCATE TABLE test.tblparted');
 note('Test: CREATE INDEX CONCURRENTLY on partial index + UPSERT');
 # Uses invalidate-catalog-snapshot-end to test catalog invalidation during UPSERT
 
-$s1 = $node->background_psql('postgres', on_error_stop => 0);
-$s2 = $node->background_psql('postgres', on_error_stop => 0);
-$s3 = $node->background_psql('postgres', on_error_stop => 0);
+$s1 = PostgreSQL::Test::Session->new(node => $node);
+$s2 = PostgreSQL::Test::Session->new(node => $node);
+$s3 = PostgreSQL::Test::Session->new(node => $node);
 
-$s1_pid = $s1->query_safe('SELECT pg_backend_pid()');
+$s1_pid = $s1->query_oneval('SELECT pg_backend_pid()');
 
 # s1 attaches BOTH injection points - the unique constraint check AND catalog snapshot
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('check-exclusion-or-unique-constraint-no-conflict', 'wait');
 ]);
 
-$s1->query_until(
-	qr/attaching_injection_point/, q[
-\echo attaching_injection_point
-SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');
-]);
+$s1->do(q[SELECT injection_points_attach('invalidate-catalog-snapshot-end', 'wait');]);
 
 # In cases of cache clobbering, s1 may hit the injection point during attach.
 # Wait for that session to become idle (attach completed), or wake it up if
@@ -781,33 +649,25 @@ if (!wait_for_idle($node, $s1_pid))
 	]);
 }
 
-$s2->query_safe(
+$s2->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('exec-insert-before-insert-speculative', 'wait');
 ]);
 
-$s3->query_safe(
+$s3->do(
 	q[
 SELECT injection_points_set_local();
 SELECT injection_points_attach('define-index-before-set-valid', 'wait');
 ]);
 
 # s3: Start CREATE INDEX CONCURRENTLY (blocks on define-index-before-set-valid)
-$s3->query_until(
-	qr/starting_create_index/, q[
-\echo starting_create_index
-CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tblexpr(abs(i)) WHERE i < 10000;
-]);
+$s3->do_async(q[CREATE UNIQUE INDEX CONCURRENTLY tbl_pkey_special_duplicate ON test.tblexpr(abs(i)) WHERE i < 10000;]);
 
 ok_injection_point($node, 'define-index-before-set-valid');
 
 # s1: Start UPSERT (blocks on invalidate-catalog-snapshot-end)
-$s1->query_until(
-	qr/starting_upsert_s1/, q[
-\echo starting_upsert_s1
-INSERT INTO test.tblexpr VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
-]);
+$s1->do_async(q[INSERT INTO test.tblexpr VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'invalidate-catalog-snapshot-end');
 
@@ -815,11 +675,7 @@ ok_injection_point($node, 'invalidate-catalog-snapshot-end');
 wakeup_injection_point($node, 'define-index-before-set-valid');
 
 # s2: Start UPSERT (blocks on exec-insert-before-insert-speculative)
-$s2->query_until(
-	qr/starting_upsert_s2/, q[
-\echo starting_upsert_s2
-INSERT INTO test.tblexpr VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();
-]);
+$s2->do_async(q[INSERT INTO test.tblexpr VALUES(13,now()) ON CONFLICT (abs(i)) WHERE i < 100 DO UPDATE SET updated_at = now();]);
 
 ok_injection_point($node, 'exec-insert-before-insert-speculative');
 wakeup_injection_point($node, 'invalidate-catalog-snapshot-end');
@@ -920,33 +776,23 @@ SELECT injection_points_wakeup('$point_name');
 ]);
 }
 
-# Wait for any pending query to complete, capture stderr, and close the session.
-# Returns the stderr output (excluding internal markers).
+# Wait for any pending query to complete and close the session.
+# Returns empty string on success, error message on failure.
 sub safe_quit
 {
 	my ($session) = @_;
 
-	# Send a marker and wait for it to ensure any pending query completes
-	my $banner = "safe_quit_marker";
-	my $banner_match = qr/(^|\n)$banner\r?\n/;
+	# Wait for any async queries to complete
+	$session->wait_for_completion;
 
-	$session->{stdin} .= "\\echo $banner\n\\warn $banner\n";
-
-	pump_until(
-		$session->{run}, $session->{timeout},
-		\$session->{stdout}, $banner_match);
-	pump_until(
-		$session->{run}, $session->{timeout},
-		\$session->{stderr}, $banner_match);
-
-	# Capture stderr (excluding the banner)
-	my $stderr = $session->{stderr};
-	$stderr =~ s/$banner_match//;
+	# Check connection status
+	my $status = $session->conn_status;
 
 	# Close the session
-	$session->quit;
+	$session->close;
 
-	return $stderr;
+	# Return empty string if connection was OK, otherwise return error
+	return ($status == PostgreSQL::PqFFI::CONNECTION_OK()) ? '' : 'connection error';
 }
 
 # Helper function: verify that the given sessions exit cleanly.
diff --git a/src/test/modules/test_misc/t/011_lock_stats.pl b/src/test/modules/test_misc/t/011_lock_stats.pl
index 45d7d26f70c..00c1ab00df2 100644
--- a/src/test/modules/test_misc/t/011_lock_stats.pl
+++ b/src/test/modules/test_misc/t/011_lock_stats.pl
@@ -19,6 +19,7 @@ use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
+use PostgreSQL::Test::Session;
 use Test::More;
 
 plan skip_all => 'Injection points not supported by this build'
@@ -32,15 +33,12 @@ my $node;
 # Setup the 2 sessions
 sub setup_sessions
 {
-	$s1 = $node->background_psql('postgres');
-	$s2 = $node->background_psql('postgres');
+	$s1 = PostgreSQL::Test::Session->new(node => $node);
+	$s2 = PostgreSQL::Test::Session->new(node => $node);
 
 	# Setup injection points for the waiting session
-	$s2->query_until(
-		qr/attaching_injection_point/, q[
-			\echo attaching_injection_point
-			SELECT injection_points_attach('deadlock-timeout-fired', 'wait');
-		]);
+	$s2->do(
+		q[SELECT injection_points_attach('deadlock-timeout-fired', 'wait');]);
 }
 
 # Fetch waits and wait_time from pg_stat_lock for a given lock type
@@ -98,7 +96,7 @@ setup_sessions();
 
 my $log_offset = -s $node->logfile;
 
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT pg_stat_reset_shared('lock');
 BEGIN;
@@ -106,17 +104,13 @@ LOCK TABLE test_stat_tab;
 ]);
 
 # s2 setup
-$s2->query_safe(
+$s2->do(
 	q[
 BEGIN;
 SELECT pg_stat_force_next_flush();
 ]);
 # s2 blocks on LOCK.
-$s2->query_until(
-	qr/lock_s2/, q[
-\echo lock_s2
-LOCK TABLE test_stat_tab;
-]);
+$s2->do_async(q(LOCK TABLE test_stat_tab;));
 
 wait_and_detach($node, 'deadlock-timeout-fired');
 
@@ -136,8 +130,9 @@ $node->safe_psql(
 $node->wait_for_log(qr/logging memory contexts/, $log_offset);
 
 # deadlock_timeout fired, now commit in s1 and s2
-$s1->query_safe(q(COMMIT));
-$s2->query_safe(q(COMMIT));
+$s1->do(q(COMMIT));
+$s2->wait_for_completion;
+$s2->do(q(COMMIT));
 
 # check that pg_stat_lock has been updated
 wait_for_pg_stat_lock($node, 'relation');
@@ -158,8 +153,8 @@ is( scalar @still_waiting,
 );
 
 # close sessions
-$s1->quit;
-$s2->quit;
+$s1->close;
+$s2->close;
 
 ####### transaction lock
 
@@ -167,27 +162,31 @@ setup_sessions();
 
 $log_offset = -s $node->logfile;
 
-$s1->query_safe(
+# The INSERT must autocommit before the explicit transaction is opened, so
+# that session s2 can see rows k1/k2/k3 and block on s1's row lock.  Send it
+# separately from the BEGIN block: a single multi-statement query containing
+# BEGIN would run the INSERT inside the still-open transaction, leaving the
+# rows invisible to s2 (so its UPDATE would match nothing and never wait).
+$s1->do(
 	q[
 SELECT pg_stat_reset_shared('lock');
 INSERT INTO test_stat_tab(key, value) VALUES('k1', 1), ('k2', 1), ('k3', 1);
+]);
+$s1->do(
+	q[
 BEGIN;
 UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';
 ]);
 
 # s2 setup
-$s2->query_safe(
+$s2->do(
 	q[
 SET log_lock_waits = on;
 BEGIN;
 SELECT pg_stat_force_next_flush();
 ]);
 # s2 blocks here on UPDATE
-$s2->query_until(
-	qr/lock_s2/, q[
-\echo lock_s2
-UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';
-]);
+$s2->do_async(q(UPDATE test_stat_tab SET value = value + 1 WHERE key = 'k1';));
 
 wait_and_detach($node, 'deadlock-timeout-fired');
 
@@ -196,8 +195,9 @@ $node->wait_for_log(qr/still waiting for ShareLock on transaction/,
 	$log_offset);
 
 # deadlock_timeout fired, now commit in s1 and s2
-$s1->query_safe(q(COMMIT));
-$s2->query_safe(q(COMMIT));
+$s1->do(q(COMMIT));
+$s2->wait_for_completion;
+$s2->do(q(COMMIT));
 
 # check that pg_stat_lock has been updated
 wait_for_pg_stat_lock($node, 'transactionid');
@@ -208,8 +208,8 @@ ok(1, "Lock stats ok for transactionid");
 $node->wait_for_log(qr/acquired ShareLock on transaction/, $log_offset);
 
 # Close sessions
-$s1->quit;
-$s2->quit;
+$s1->close;
+$s2->close;
 
 ####### advisory lock
 
@@ -217,25 +217,21 @@ setup_sessions();
 
 $log_offset = -s $node->logfile;
 
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT pg_stat_reset_shared('lock');
 SELECT pg_advisory_lock(1);
 ]);
 
 # s2 setup
-$s2->query_safe(
+$s2->do(
 	q[
 SET log_lock_waits = on;
 BEGIN;
 SELECT pg_stat_force_next_flush();
 ]);
 # s2 blocks on the advisory lock.
-$s2->query_until(
-	qr/lock_s2/, q[
-\echo lock_s2
-SELECT pg_advisory_lock(1);
-]);
+$s2->do_async(q(SELECT pg_advisory_lock(1);));
 
 wait_and_detach($node, 'deadlock-timeout-fired');
 
@@ -244,8 +240,9 @@ $node->wait_for_log(qr/still waiting for ExclusiveLock on advisory lock/,
 	$log_offset);
 
 # deadlock_timeout fired, now unlock and commit s2
-$s1->query_safe(q(SELECT pg_advisory_unlock(1)));
-$s2->query_safe(
+$s1->do(q(SELECT pg_advisory_unlock(1)));
+$s2->wait_for_completion;
+$s2->do(
 	q[
 SELECT pg_advisory_unlock(1);
 COMMIT;
@@ -260,8 +257,8 @@ ok(1, "Lock stats ok for advisory");
 $node->wait_for_log(qr/acquired ExclusiveLock on advisory lock/, $log_offset);
 
 # Close sessions
-$s1->quit;
-$s2->quit;
+$s1->close;
+$s2->close;
 
 ####### Ensure log_lock_waits has no impact
 
@@ -269,7 +266,7 @@ setup_sessions();
 
 $log_offset = -s $node->logfile;
 
-$s1->query_safe(
+$s1->do(
 	q[
 SELECT pg_stat_reset_shared('lock');
 BEGIN;
@@ -277,24 +274,21 @@ LOCK TABLE test_stat_tab;
 ]);
 
 # s2 setup
-$s2->query_safe(
+$s2->do(
 	q[
 SET log_lock_waits = off;
 BEGIN;
 SELECT pg_stat_force_next_flush();
 ]);
 # s2 blocks on LOCK.
-$s2->query_until(
-	qr/lock_s2/, q[
-\echo lock_s2
-LOCK TABLE test_stat_tab;
-]);
+$s2->do_async(q(LOCK TABLE test_stat_tab;));
 
 wait_and_detach($node, 'deadlock-timeout-fired');
 
 # deadlock_timeout fired, now commit in s1 and s2
-$s1->query_safe(q(COMMIT));
-$s2->query_safe(q(COMMIT));
+$s1->do(q(COMMIT));
+$s2->wait_for_completion;
+$s2->do(q(COMMIT));
 
 # check that pg_stat_lock has been updated
 wait_for_pg_stat_lock($node, 'relation');
@@ -310,8 +304,8 @@ ok( !$node->log_contains(
 );
 
 # close sessions
-$s1->quit;
-$s2->quit;
+$s1->close;
+$s2->close;
 
 # cleanup
 $node->safe_psql('postgres', q[DROP TABLE test_stat_tab;]);
diff --git a/src/test/modules/test_misc/t/013_temp_obj_multisession.pl b/src/test/modules/test_misc/t/013_temp_obj_multisession.pl
index 5f3cc7d2fc5..0b15b0bde08 100644
--- a/src/test/modules/test_misc/t/013_temp_obj_multisession.pl
+++ b/src/test/modules/test_misc/t/013_temp_obj_multisession.pl
@@ -20,21 +20,21 @@ use strict;
 use warnings;
 use PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
-use PostgreSQL::Test::BackgroundPsql;
+use PostgreSQL::Test::Session;
 use Test::More;
 
 my $node = PostgreSQL::Test::Cluster->new('temp_lock');
 $node->init;
 $node->start;
 
-# Owner session.  Created via background_psql so it stays alive while
-# the second session probes its temp objects.
-my $psql1 = $node->background_psql('postgres');
+# Owner session.  Created as a persistent libpq session so it stays alive
+# while the second session probes its temp objects.
+my $psql1 = PostgreSQL::Test::Session->new(node => $node);
 
 # Initially create the table without an index, so read paths go straight
 # through the read-stream / buffer-manager entry points without being
 # masked by an index scan that would hit ReadBuffer_common from nbtree.
-$psql1->query_safe(q(CREATE TEMP TABLE foo AS SELECT 42 AS val;));
+$psql1->do(q(CREATE TEMP TABLE foo AS SELECT 42 AS val;));
 
 # Resolve the owner's temp schema so the probing session can refer to
 # the table by a fully-qualified name.
@@ -130,7 +130,7 @@ like($stderr,
 # Now create an index to exercise the index-scan path.  nbtree calls
 # ReadBuffer (which is ReadBufferExtended -> ReadBuffer_common), so
 # this exercises a different chain of buffer-manager entry points.
-$psql1->query_safe(q(CREATE INDEX ON foo(val);));
+$psql1->do(q(CREATE INDEX ON foo(val);));
 
 $node->psql(
 	'postgres',
@@ -156,7 +156,7 @@ like($stderr, qr/cannot alter temporary tables of other sessions/,
 # operations -- they don't read the underlying table -- which
 # documents the boundary between catalog and data access for temp
 # objects.
-$psql1->query_safe(
+$psql1->do(
 		q[CREATE FUNCTION pg_temp.foo_id(r foo) RETURNS int LANGUAGE SQL ]
 	  . q[AS 'SELECT r.val';]);
 
@@ -187,7 +187,7 @@ is($stderr, '', 'DROP TABLE is allowed');
 # into the creator's pg_temp namespace with an auto-dependency on
 # the borrowed type, so it disappears together with the session that
 # created it.
-$psql1->query_safe(q(CREATE TEMP TABLE foo2 AS SELECT 42 AS val;));
+$psql1->do(q(CREATE TEMP TABLE foo2 AS SELECT 42 AS val;));
 
 $node->psql(
 	'postgres',
@@ -216,8 +216,8 @@ my $foo2_oid = $node->safe_psql('postgres',
 # Cross-session LOCK TABLE scenario.  Ensure that LockRelationOid is working
 # properly for other temp tables since this mechanism is also used by
 # autovacuum during orphaned tables cleanup.
-my $psql2 = $node->background_psql('postgres');
-$psql2->query_safe(
+my $psql2 = PostgreSQL::Test::Session->new(node => $node);
+$psql2->do(
 	qq{
 	BEGIN;
 	LOCK TABLE $tempschema.foo2 IN ACCESS SHARE MODE;
@@ -233,15 +233,15 @@ $psql2->query_safe(
 # owner will try to acquire deletion lock all its temp objects via
 # findDependentObjects.
 my $log_offset = -s $node->logfile;
-$psql1->quit;
+$psql1->close;
 
 # Check whether session-exit cleanup is blocked.
 $node->wait_for_log(qr/waiting for AccessExclusiveLock on relation $foo2_oid/,
 	$log_offset);
 
 # Release lock on foo2 and allow session-exit cleanup to finish.
-$psql2->query_safe(q(COMMIT;));
-$psql2->quit;
+$psql2->do(q(COMMIT;));
+$psql2->close;
 
 # After releasing the lock, the owner can finally acquire
 # AccessExclusiveLock on foo2 and finish session-exit cleanup.  Verify
diff --git a/src/test/modules/test_slru/t/001_multixact.pl b/src/test/modules/test_slru/t/001_multixact.pl
index f6f45895ebd..2d86434d7bc 100644
--- a/src/test/modules/test_slru/t/001_multixact.pl
+++ b/src/test/modules/test_slru/t/001_multixact.pl
@@ -6,6 +6,7 @@ use strict;
 use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 
 use Test::More;
@@ -30,8 +31,8 @@ $node->safe_psql('postgres', q(CREATE EXTENSION test_slru));
 # lost.
 
 # Create the first multixact
-my $bg_psql = $node->background_psql('postgres');
-my $multi1 = $bg_psql->query_safe(q(SELECT test_create_multixact();));
+my $bg_session = PostgreSQL::Test::Session->new(node => $node);
+my $multi1 = $bg_session->query_oneval(q(SELECT test_create_multixact();));
 
 # Assign the middle multixact. Use an injection point to prevent it
 # from being fully recorded.
@@ -39,11 +40,9 @@ $node->safe_psql('postgres',
 	q{SELECT injection_points_attach('multixact-create-from-members','wait');}
 );
 
-$bg_psql->query_until(
-	qr/assigning lost multi/, q(
-\echo assigning lost multi
-	SELECT test_create_multixact();
-));
+# Start the second multixact creation asynchronously - it will block at
+# the injection point
+$bg_session->do_async(q(SELECT test_create_multixact();));
 
 $node->wait_for_event('client backend', 'multixact-create-from-members');
 $node->safe_psql('postgres',
@@ -52,10 +51,10 @@ $node->safe_psql('postgres',
 # Create the third multixid
 my $multi2 = $node->safe_psql('postgres', q{SELECT test_create_multixact();});
 
-# All set and done, it's time for hard restart
+# All set and done, it's time for hard restart. The background session
+# will be terminated by the crash.
 $node->stop('immediate');
 $node->start;
-$bg_psql->{run}->finish;
 
 # Verify that the recorded multixids are readable
 is( $node->safe_psql('postgres', qq{SELECT test_read_multixact('$multi1');}),
diff --git a/src/test/modules/xid_wraparound/t/001_emergency_vacuum.pl b/src/test/modules/xid_wraparound/t/001_emergency_vacuum.pl
index 213f9052ed2..304076735b4 100644
--- a/src/test/modules/xid_wraparound/t/001_emergency_vacuum.pl
+++ b/src/test/modules/xid_wraparound/t/001_emergency_vacuum.pl
@@ -4,6 +4,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -47,17 +48,10 @@ CREATE TABLE small_trunc(id serial primary key, data text, filler text default r
 INSERT INTO small_trunc(data) SELECT generate_series(1,15000);
 ]);
 
-# Bump the query timeout to avoid false negatives on slow test systems.
-my $psql_timeout_secs = 4 * $PostgreSQL::Test::Utils::timeout_default;
-
 # Start a background session, which holds a transaction open, preventing
 # autovacuum from advancing relfrozenxid and datfrozenxid.
-my $background_psql = $node->background_psql(
-	'postgres',
-	on_error_stop => 0,
-	timeout => $psql_timeout_secs);
-$background_psql->set_query_timer_restart();
-$background_psql->query_safe(
+my $background_session = PostgreSQL::Test::Session->new(node => $node);
+$background_session->do(
 	qq[
 	BEGIN;
 	DELETE FROM large WHERE id % 2 = 0;
@@ -89,8 +83,8 @@ my $log_offset = -s $node->logfile;
 
 # Finish the old transaction, to allow vacuum freezing to advance
 # relfrozenxid and datfrozenxid again.
-$background_psql->query_safe(qq[COMMIT]);
-$background_psql->quit;
+$background_session->do(qq[COMMIT;]);
+$background_session->close;
 
 # Wait until autovacuum processed all tables and advanced the
 # system-wide oldest-XID.
diff --git a/src/test/modules/xid_wraparound/t/002_limits.pl b/src/test/modules/xid_wraparound/t/002_limits.pl
index 86632a8d510..0ef67d0f4b8 100644
--- a/src/test/modules/xid_wraparound/t/002_limits.pl
+++ b/src/test/modules/xid_wraparound/t/002_limits.pl
@@ -10,6 +10,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 use Time::HiRes qw(usleep);
@@ -29,6 +30,8 @@ $node->append_conf(
 	'postgresql.conf', qq[
 autovacuum_naptime = 1s
 log_autovacuum_min_duration = 0
+log_connections = on
+log_statement = 'all'
 ]);
 $node->start;
 $node->safe_psql('postgres', 'CREATE EXTENSION xid_wraparound');
@@ -41,16 +44,10 @@ CREATE TABLE wraparoundtest(t text) WITH (autovacuum_enabled = off);
 INSERT INTO wraparoundtest VALUES ('start');
 ]);
 
-# Bump the query timeout to avoid false negatives on slow test systems.
-my $psql_timeout_secs = 4 * $PostgreSQL::Test::Utils::timeout_default;
-
 # Start a background session, which holds a transaction open, preventing
 # autovacuum from advancing relfrozenxid and datfrozenxid.
-my $background_psql = $node->background_psql(
-	'postgres',
-	on_error_stop => 0,
-	timeout => $psql_timeout_secs);
-$background_psql->query_safe(
+my $background_session = PostgreSQL::Test::Session->new(node => $node);
+$background_session->do(
 	qq[
 	BEGIN;
 	INSERT INTO wraparoundtest VALUES ('oldxact');
@@ -108,8 +105,8 @@ like(
 
 # Finish the old transaction, to allow vacuum freezing to advance
 # relfrozenxid and datfrozenxid again.
-$background_psql->query_safe(qq[COMMIT]);
-$background_psql->quit;
+$background_session->do(qq[COMMIT;]);
+$background_session->close;
 
 # VACUUM, to freeze the tables and advance datfrozenxid.
 #
@@ -122,8 +119,8 @@ $node->safe_psql('postgres', 'VACUUM');
 # the system-wide oldest-XID.
 $ret =
   $node->poll_query_until('postgres',
-	qq[INSERT INTO wraparoundtest VALUES ('after VACUUM')],
-	'INSERT 0 1');
+	qq[INSERT INTO wraparoundtest VALUES ('after VACUUM') RETURNING true],
+						 );
 
 # Check the table contents
 $ret = $node->safe_psql('postgres', qq[SELECT * from wraparoundtest]);
diff --git a/src/test/modules/xid_wraparound/t/004_notify_freeze.pl b/src/test/modules/xid_wraparound/t/004_notify_freeze.pl
index d0a1f1fe2fc..f2fa4e5a6b9 100644
--- a/src/test/modules/xid_wraparound/t/004_notify_freeze.pl
+++ b/src/test/modules/xid_wraparound/t/004_notify_freeze.pl
@@ -7,6 +7,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use Test::More;
 
 my $node = PostgreSQL::Test::Cluster->new('node');
@@ -24,9 +25,9 @@ $node->safe_psql('postgres',
 	'ALTER DATABASE template0 WITH ALLOW_CONNECTIONS true');
 
 # Start Session 1 and leave it idle in transaction
-my $psql_session1 = $node->background_psql('postgres');
-$psql_session1->query_safe('listen s;');
-$psql_session1->query_safe('begin;');
+my $session1 = PostgreSQL::Test::Session->new(node => $node);
+$session1->do('LISTEN s');
+$session1->do('BEGIN');
 
 # Send some notifys from other sessions
 for my $i (1 .. 10)
@@ -54,18 +55,20 @@ my $datafronzenxid_freeze = $node->safe_psql('postgres',
 	"select min(datfrozenxid::text::bigint) from pg_database");
 ok($datafronzenxid_freeze > $datafronzenxid, 'datfrozenxid advanced');
 
-# On Session 1, commit and ensure that the all the notifications are
+# On Session 1, commit and ensure that all the notifications are
 # received. This depends on correctly freezing the XIDs in the pending
 # notification entries.
-my $res = $psql_session1->query_safe('commit;');
-my $notifications_count = 0;
-foreach my $i (split('\n', $res))
+$session1->do('COMMIT');
+
+my $notifications = $session1->get_all_notifications();
+is(scalar(@$notifications), 10, 'received all committed notifications');
+
+my $expected_payload = 1;
+foreach my $notify (@$notifications)
 {
-	$notifications_count++;
-	like($i,
-		qr/Asynchronous notification "s" with payload "$notifications_count" received/
-	);
+	is($notify->{channel}, 's', "notification $expected_payload has correct channel");
+	is($notify->{payload}, $expected_payload, "notification $expected_payload has correct payload");
+	$expected_payload++;
 }
-is($notifications_count, 10, 'received all committed notifications');
 
 done_testing();
diff --git a/src/test/postmaster/t/002_connection_limits.pl b/src/test/postmaster/t/002_connection_limits.pl
index 8c67c4a86c7..1b4a97d16f4 100644
--- a/src/test/postmaster/t/002_connection_limits.pl
+++ b/src/test/postmaster/t/002_connection_limits.pl
@@ -7,6 +7,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -33,19 +34,20 @@ GRANT pg_use_reserved_connections TO regress_reserved;
 CREATE USER regress_superuser LOGIN SUPERUSER;
 });
 
+my $node_connstr = $node->connstr('postgres');
+my $libdir =  $node->config_data('--libdir');
+
 # 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
+sub session_as_user
 {
 	my $user = shift;
+    my $connstr = "$node_connstr user=$user";
 
-	return $node->background_psql(
-		'postgres',
-		on_error_die => 1,
-		extra_params => [ '--username' => $user ]);
+	return PostgreSQL::Test::Session->new( connstr => $connstr, libdir => $libdir);
 }
 
 # Like connect_fails(), except that we also wait for the failed backend to
@@ -82,9 +84,9 @@ $node->restart;
 my @sessions = ();
 my @raw_connections = ();
 
-push(@sessions, background_psql_as_user('regress_regular'));
-push(@sessions, background_psql_as_user('regress_regular'));
-push(@sessions, background_psql_as_user('regress_regular'));
+push(@sessions, session_as_user('regress_regular'));
+push(@sessions, session_as_user('regress_regular'));
+push(@sessions, session_as_user('regress_regular'));
 connect_fails_wait(
 	$node,
 	"dbname=postgres user=regress_regular",
@@ -93,8 +95,8 @@ connect_fails_wait(
 	  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'));
+push(@sessions, session_as_user('regress_reserved'));
+push(@sessions, session_as_user('regress_reserved'));
 connect_fails_wait(
 	$node,
 	"dbname=postgres user=regress_reserved",
@@ -103,7 +105,7 @@ connect_fails_wait(
 	  qr/FATAL:  remaining connection slots are reserved for roles with the SUPERUSER attribute/
 );
 
-push(@sessions, background_psql_as_user('regress_superuser'));
+push(@sessions, session_as_user('regress_superuser'));
 connect_fails_wait(
 	$node,
 	"dbname=postgres user=regress_superuser",
@@ -150,7 +152,7 @@ SKIP:
 # Clean up
 foreach my $session (@sessions)
 {
-	$session->quit;
+	$session->close;
 }
 foreach my $socket (@raw_connections)
 {
diff --git a/src/test/recovery/t/009_twophase.pl b/src/test/recovery/t/009_twophase.pl
index aa73d3e106c..9fe037bb0a1 100644
--- a/src/test/recovery/t/009_twophase.pl
+++ b/src/test/recovery/t/009_twophase.pl
@@ -6,6 +6,7 @@ use strict;
 use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -331,11 +332,10 @@ $cur_primary->stop;
 $cur_standby->restart;
 
 # Acquire a snapshot in standby, before we commit the prepared transaction
-my $standby_session =
-  $cur_standby->background_psql('postgres', on_error_die => 1);
-$standby_session->query_safe("BEGIN ISOLATION LEVEL REPEATABLE READ");
+my $standby_session = PostgreSQL::Test::Session->new(node => $cur_standby);
+$standby_session->do("BEGIN ISOLATION LEVEL REPEATABLE READ");
 $psql_out =
-  $standby_session->query_safe("SELECT count(*) FROM t_009_tbl_standby_mvcc");
+  $standby_session->query_oneval("SELECT count(*) FROM t_009_tbl_standby_mvcc");
 is($psql_out, '0',
 	"Prepared transaction not visible in standby before commit");
 
@@ -349,17 +349,17 @@ COMMIT PREPARED 'xact_009_standby_mvcc';
 
 # Still not visible to the old snapshot
 $psql_out =
-  $standby_session->query_safe("SELECT count(*) FROM t_009_tbl_standby_mvcc");
+  $standby_session->query_oneval("SELECT count(*) FROM t_009_tbl_standby_mvcc");
 is($psql_out, '0',
 	"Committed prepared transaction not visible to old snapshot in standby");
 
 # Is visible to a new snapshot
-$standby_session->query_safe("COMMIT");
+$standby_session->do("COMMIT");
 $psql_out =
-  $standby_session->query_safe("SELECT count(*) FROM t_009_tbl_standby_mvcc");
+  $standby_session->query_oneval("SELECT count(*) FROM t_009_tbl_standby_mvcc");
 is($psql_out, '2',
 	"Committed prepared transaction is visible to new snapshot in standby");
-$standby_session->quit;
+$standby_session->close;
 
 ###############################################################################
 # Check for a lock conflict between prepared transaction with DDL inside and
diff --git a/src/test/recovery/t/013_crash_restart.pl b/src/test/recovery/t/013_crash_restart.pl
index 0fde920713e..b62b0000edf 100644
--- a/src/test/recovery/t/013_crash_restart.pl
+++ b/src/test/recovery/t/013_crash_restart.pl
@@ -149,7 +149,7 @@ ok( pump_until(
 $monitor->finish;
 
 # Wait till server restarts
-is($node->poll_query_until('postgres', undef, ''),
+is($node->poll_until_connection('postgres'),
 	"1", "reconnected after SIGQUIT");
 
 
@@ -238,7 +238,7 @@ ok( pump_until(
 $monitor->finish;
 
 # Wait till server restarts
-is($node->poll_query_until('postgres', undef, ''),
+is($node->poll_until_connection('postgres'),
 	"1", "reconnected after SIGKILL");
 
 # Make sure the committed rows survived, in-progress ones not
diff --git a/src/test/recovery/t/022_crash_temp_files.pl b/src/test/recovery/t/022_crash_temp_files.pl
index 5de9b0fb0eb..6c55fcf40b1 100644
--- a/src/test/recovery/t/022_crash_temp_files.pl
+++ b/src/test/recovery/t/022_crash_temp_files.pl
@@ -146,7 +146,7 @@ ok( pump_until(
 $killme2->finish;
 
 # Wait till server finishes restarting
-$node->poll_query_until('postgres', undef, '');
+$node->poll_until_connection('postgres');
 
 # Check for temporary files
 is( $node->safe_psql(
@@ -253,7 +253,7 @@ ok( pump_until(
 $killme2->finish;
 
 # Wait till server finishes restarting
-$node->poll_query_until('postgres', undef, '');
+$node->poll_until_connection('postgres');
 
 # Check for temporary files -- should be there
 is( $node->safe_psql(
diff --git a/src/test/recovery/t/031_recovery_conflict.pl b/src/test/recovery/t/031_recovery_conflict.pl
index 7a740f69806..74349749170 100644
--- a/src/test/recovery/t/031_recovery_conflict.pl
+++ b/src/test/recovery/t/031_recovery_conflict.pl
@@ -7,6 +7,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -67,8 +68,7 @@ $node_primary->wait_for_replay_catchup($node_standby);
 
 
 # a longrunning psql that we can use to trigger conflicts
-my $psql_standby =
-  $node_standby->background_psql($test_db, on_error_stop => 0);
+my $psql_standby = PostgreSQL::Test::Session->new(node => $node_standby, dbname => $test_db);
 my $expected_conflicts = 0;
 
 
@@ -96,7 +96,7 @@ my $cursor1 = "test_recovery_conflict_cursor";
 
 # DECLARE and use a cursor on standby, causing buffer with the only block of
 # the relation to be pinned on the standby
-my $res = $psql_standby->query_safe(
+my $res = $psql_standby->query_oneval(
 	qq[
     BEGIN;
     DECLARE $cursor1 CURSOR FOR SELECT b FROM $table1;
@@ -119,7 +119,7 @@ $node_primary->safe_psql($test_db, qq[VACUUM FREEZE $table1;]);
 $node_primary->wait_for_replay_catchup($node_standby);
 
 check_conflict_log("User was holding shared buffer pin for too long");
-$psql_standby->reconnect_and_clear();
+$psql_standby->reconnect();
 check_conflict_stat("bufferpin");
 
 
@@ -132,7 +132,7 @@ $node_primary->safe_psql($test_db,
 $node_primary->wait_for_replay_catchup($node_standby);
 
 # DECLARE and FETCH from cursor on the standby
-$res = $psql_standby->query_safe(
+$res = $psql_standby->query_oneval(
 	qq[
         BEGIN;
         DECLARE $cursor1 CURSOR FOR SELECT b FROM $table1;
@@ -152,7 +152,7 @@ $node_primary->wait_for_replay_catchup($node_standby);
 
 check_conflict_log(
 	"User query might have needed to see row versions that must be removed");
-$psql_standby->reconnect_and_clear();
+$psql_standby->reconnect();
 check_conflict_stat("snapshot");
 
 
@@ -161,7 +161,7 @@ $sect = "lock conflict";
 $expected_conflicts++;
 
 # acquire lock to conflict with
-$res = $psql_standby->query_safe(
+$res = $psql_standby->query_oneval(
 	qq[
         BEGIN;
         LOCK TABLE $table1 IN ACCESS SHARE MODE;
@@ -175,7 +175,7 @@ $node_primary->safe_psql($test_db, qq[DROP TABLE $table1;]);
 $node_primary->wait_for_replay_catchup($node_standby);
 
 check_conflict_log("User was holding a relation lock for too long");
-$psql_standby->reconnect_and_clear();
+$psql_standby->reconnect();
 check_conflict_stat("lock");
 
 
@@ -186,7 +186,7 @@ $expected_conflicts++;
 # DECLARE a cursor for a query which, with sufficiently low work_mem, will
 # spill tuples into temp files in the temporary tablespace created during
 # setup.
-$res = $psql_standby->query_safe(
+$res = $psql_standby->query_oneval(
 	qq[
         BEGIN;
         SET work_mem = '64kB';
@@ -205,7 +205,7 @@ $node_primary->wait_for_replay_catchup($node_standby);
 
 check_conflict_log(
 	"User was or might have been using tablespace that must be dropped");
-$psql_standby->reconnect_and_clear();
+$psql_standby->reconnect();
 check_conflict_stat("tablespace");
 
 
@@ -220,8 +220,9 @@ $node_standby->adjust_conf(
 	'postgresql.conf',
 	'max_standby_streaming_delay',
 	"${PostgreSQL::Test::Utils::timeout_default}s");
+$psql_standby->close;
 $node_standby->restart();
-$psql_standby->reconnect_and_clear();
+$psql_standby->reconnect();
 
 # Generate a few dead rows, to later be cleaned up by vacuum. Then acquire a
 # lock on another relation in a prepared xact, so it's held continuously by
@@ -244,12 +245,15 @@ SELECT txid_current();
 
 $node_primary->wait_for_replay_catchup($node_standby);
 
-$res = $psql_standby->query_until(
-	qr/^1$/m, qq[
+$res = $psql_standby->query_oneval(
+	qq[
     BEGIN;
     -- hold pin
     DECLARE $cursor1 CURSOR FOR SELECT a FROM $table1;
     FETCH FORWARD FROM $cursor1;
+]);
+is ($res, 1, "pin held");
+$psql_standby->do_async(qq[
     -- wait for lock held by prepared transaction
 	SELECT * FROM $table2;
     ]);
@@ -270,15 +274,16 @@ $node_primary->safe_psql($test_db, qq[VACUUM FREEZE $table1;]);
 $node_primary->wait_for_replay_catchup($node_standby);
 
 check_conflict_log("User transaction caused buffer deadlock with recovery.");
-$psql_standby->reconnect_and_clear();
+$psql_standby->reconnect();
 check_conflict_stat("deadlock");
 
 # clean up for next tests
 $node_primary->safe_psql($test_db, qq[ROLLBACK PREPARED 'lock';]);
 $node_standby->adjust_conf('postgresql.conf', 'max_standby_streaming_delay',
-	'50ms');
+						   '50ms');
+$psql_standby->close;
 $node_standby->restart();
-$psql_standby->reconnect_and_clear();
+$psql_standby->reconnect();
 
 
 # Check that expected number of conflicts show in pg_stat_database. Needs to
@@ -302,7 +307,7 @@ check_conflict_log("User was connected to a database that must be dropped");
 
 # explicitly shut down psql instances gracefully - to avoid hangs or worse on
 # windows
-$psql_standby->quit;
+$psql_standby->close;
 
 $node_standby->stop();
 $node_primary->stop();
diff --git a/src/test/recovery/t/037_invalid_database.pl b/src/test/recovery/t/037_invalid_database.pl
index a0947108700..b10a79d0ee7 100644
--- a/src/test/recovery/t/037_invalid_database.pl
+++ b/src/test/recovery/t/037_invalid_database.pl
@@ -5,6 +5,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -91,41 +92,38 @@ is($node->psql('postgres', 'DROP DATABASE regression_invalid'),
 # dropping the database, making it a suitable point to wait.  Since relcache
 # init reads pg_tablespace, establish each connection before locking.  This
 # avoids a connection-time hang with debug_discard_caches.
-my $cancel = $node->background_psql('postgres', on_error_stop => 1);
-my $bgpsql = $node->background_psql('postgres', on_error_stop => 0);
-my $pid = $bgpsql->query('SELECT pg_backend_pid()');
+my $cancel = PostgreSQL::Test::Session->new(node=>$node);
+my $bgpsql = PostgreSQL::Test::Session->new(node=>$node);
+my $pid = $bgpsql->query_oneval('SELECT pg_backend_pid()');
 
 # create the database, prevent drop database via lock held by a 2PC transaction
-$bgpsql->query_safe(
-	qq(
-  CREATE DATABASE regression_invalid_interrupt;
-  BEGIN;
+is (1,  $bgpsql->do(
+		qq(
+  CREATE DATABASE regression_invalid_interrupt;),
+  qq(BEGIN;
   LOCK pg_tablespace;
-  PREPARE TRANSACTION 'lock_tblspc';));
+  PREPARE TRANSACTION 'lock_tblspc';)));
 
 # Try to drop. This will wait due to the still held lock.
-$bgpsql->query_until(qr//, "DROP DATABASE regression_invalid_interrupt;\n");
+$bgpsql->do_async("DROP DATABASE regression_invalid_interrupt;");
 
 
 # Once the DROP DATABASE is waiting for the lock, interrupt it.
-ok( $cancel->query_safe(
-		qq(
+my $cancel_res = $cancel->query(
+		qq[
 	DO \$\$
 	BEGIN
 		WHILE NOT EXISTS(SELECT * FROM pg_locks WHERE NOT granted AND relation = 'pg_tablespace'::regclass AND mode = 'AccessShareLock') LOOP
 			PERFORM pg_sleep(.1);
 		END LOOP;
 	END\$\$;
-	SELECT pg_cancel_backend($pid);)),
-	"canceling DROP DATABASE");
-$cancel->quit();
+	SELECT pg_cancel_backend($pid)]);
+is (2, $cancel_res->{status}, "canceling DROP DATABASE"); # COMMAND_TUPLES_OK
+$cancel->close();
 
+$bgpsql->wait_for_completion;
 # wait for cancellation to be processed
-ok( pump_until(
-		$bgpsql->{run}, $bgpsql->{timeout},
-		\$bgpsql->{stderr}, qr/canceling statement due to user request/),
-	"cancel processed");
-$bgpsql->{stderr} = '';
+pass("cancel processed");
 
 # Verify that connections to the database aren't allowed.  The backend checks
 # this before relcache init, so the lock won't interfere.
@@ -134,9 +132,12 @@ is($node->psql('regression_invalid_interrupt', ''),
 
 # To properly drop the database, we need to release the lock previously preventing
 # doing so.
-$bgpsql->query_safe(qq(ROLLBACK PREPARED 'lock_tblspc'));
-$bgpsql->query_safe(qq(DROP DATABASE regression_invalid_interrupt));
+ok($bgpsql->do(qq(ROLLBACK PREPARED 'lock_tblspc')),
+	"unblock DROP DATABASE");
 
-$bgpsql->quit();
+ok($bgpsql->query(qq(DROP DATABASE regression_invalid_interrupt)),
+	"DROP DATABASE invalid_interrupt");
+
+$bgpsql->close();
 
 done_testing();
diff --git a/src/test/recovery/t/040_standby_failover_slots_sync.pl b/src/test/recovery/t/040_standby_failover_slots_sync.pl
index f8922aaa1a2..ef16e0a8740 100644
--- a/src/test/recovery/t/040_standby_failover_slots_sync.pl
+++ b/src/test/recovery/t/040_standby_failover_slots_sync.pl
@@ -4,6 +4,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -768,17 +769,13 @@ $primary->safe_psql('postgres',
 	"SELECT pg_create_logical_replication_slot('test_slot', 'test_decoding', false, false, true);"
 );
 
-my $back_q = $primary->background_psql(
-	'postgres',
-	on_error_stop => 0,
-	timeout => $PostgreSQL::Test::Utils::timeout_default);
+my $back_q = PostgreSQL::Test::Session->new(node=>$primary);
 
 # pg_logical_slot_get_changes will be blocked until the standby catches up,
 # hence it needs to be executed in a background session.
 $offset = -s $primary->logfile;
-$back_q->query_until(
-	qr/logical_slot_get_changes/, q(
-   \echo logical_slot_get_changes
+$back_q->do_async(
+	q(
    SELECT pg_logical_slot_get_changes('test_slot', NULL, NULL);
 ));
 
@@ -796,7 +793,8 @@ $primary->reload;
 # Since there are no slots in synchronized_standby_slots, the function
 # pg_logical_slot_get_changes should now return, and the session can be
 # stopped.
-$back_q->quit;
+$back_q->wait_for_completion;
+$back_q->close;
 
 $primary->safe_psql('postgres',
 	"SELECT pg_drop_replication_slot('test_slot');");
@@ -1059,13 +1057,8 @@ $standby2->reload;
 # synchronization until the remote slot catches up.
 # The API will not return until this happens, to be able to make
 # further calls, call the API in a background process.
-my $h = $standby2->background_psql('postgres', on_error_stop => 0);
-
-$h->query_until(
-	qr/start/, q(
-	\echo start
-	SELECT pg_sync_replication_slots();
-	));
+my $h = PostgreSQL::Test::Session->new(node => $standby2);
+$h->do_async(q(SELECT pg_sync_replication_slots();));
 
 # Confirm that the slot sync is skipped due to the remote slot lagging behind
 $standby2->wait_for_log(
@@ -1104,6 +1097,7 @@ $standby2->wait_for_log(
 	qr/newly created replication slot \"lsub1_slot\" is sync-ready now/,
 	$log_offset);
 
-$h->quit;
+$h->wait_for_completion;
+$h->close;
 
 done_testing();
diff --git a/src/test/recovery/t/041_checkpoint_at_promote.pl b/src/test/recovery/t/041_checkpoint_at_promote.pl
index d0783fef9ae..fcc01334589 100644
--- a/src/test/recovery/t/041_checkpoint_at_promote.pl
+++ b/src/test/recovery/t/041_checkpoint_at_promote.pl
@@ -4,6 +4,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Time::HiRes qw(usleep);
 use Test::More;
@@ -70,11 +71,9 @@ $node_standby->safe_psql('postgres',
 # Execute a restart point on the standby, that we will now be waiting on.
 # This needs to be in the background.
 my $logstart = -s $node_standby->logfile;
-my $psql_session =
-  $node_standby->background_psql('postgres', on_error_stop => 0);
-$psql_session->query_until(
-	qr/starting_checkpoint/, q(
-   \echo starting_checkpoint
+my $psql_session = PostgreSQL::Test::Session->new(node=> $node_standby);
+$psql_session->do_async(
+	q(
    CHECKPOINT;
 ));
 
@@ -159,7 +158,7 @@ ok( pump_until(
 $killme->finish;
 
 # Wait till server finishes restarting.
-$node_standby->poll_query_until('postgres', undef, '');
+$node_standby->poll_until_connection('postgres');
 
 # After recovery, the server should be able to start.
 my $stdout;
diff --git a/src/test/recovery/t/042_low_level_backup.pl b/src/test/recovery/t/042_low_level_backup.pl
index df4ae029fe6..58489482341 100644
--- a/src/test/recovery/t/042_low_level_backup.pl
+++ b/src/test/recovery/t/042_low_level_backup.pl
@@ -10,6 +10,7 @@ use warnings FATAL => 'all';
 use File::Copy qw(copy);
 use File::Path qw(rmtree);
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -20,11 +21,10 @@ $node_primary->start;
 
 # Start backup.
 my $backup_name = 'backup1';
-my $psql = $node_primary->background_psql('postgres');
+my $psql = PostgreSQL::Test::Session->new(node => $node_primary);
 
-$psql->query_safe("SET client_min_messages TO WARNING");
-$psql->set_query_timer_restart;
-$psql->query_safe("select pg_backup_start('test label')");
+$psql->do("SET client_min_messages TO WARNING");
+$psql->query("select pg_backup_start('test label')");
 
 # Copy files.
 my $backup_dir = $node_primary->backup_dir . '/' . $backup_name;
@@ -81,9 +81,9 @@ my $stop_segment_name = $node_primary->safe_psql('postgres',
 
 # Stop backup and get backup_label, the last segment is archived.
 my $backup_label =
-  $psql->query_safe("select labelfile from pg_backup_stop()");
+  $psql->query_oneval("select labelfile from pg_backup_stop()");
 
-$psql->quit;
+$psql->close;
 
 # Rather than writing out backup_label, try to recover the backup without
 # backup_label to demonstrate that recovery will not work correctly without it,
diff --git a/src/test/recovery/t/046_checkpoint_logical_slot.pl b/src/test/recovery/t/046_checkpoint_logical_slot.pl
index 66761bf56c1..3a46f20fc28 100644
--- a/src/test/recovery/t/046_checkpoint_logical_slot.pl
+++ b/src/test/recovery/t/046_checkpoint_logical_slot.pl
@@ -8,6 +8,7 @@ use strict;
 use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 
 use Test::More;
@@ -52,13 +53,10 @@ $node->safe_psql('postgres',
 $node->safe_psql('postgres', q{checkpoint});
 
 # Generate some transactions to get RUNNING_XACTS.
-my $xacts = $node->background_psql('postgres');
-$xacts->query_until(
-	qr/run_xacts/,
-	q(\echo run_xacts
-SELECT 1 \watch 0.1
-\q
-));
+for (my $i = 0; $i < 10; $i++)
+{
+	$node->safe_psql('postgres', 'SELECT 1');
+}
 
 $node->advance_wal(20);
 
@@ -72,16 +70,11 @@ $node->advance_wal(20);
 # removing old WAL segments.
 note('starting checkpoint');
 
-my $checkpoint = $node->background_psql('postgres');
-$checkpoint->query_safe(
+$node->safe_psql('postgres',
 	q(select injection_points_attach('checkpoint-before-old-wal-removal','wait'))
 );
-$checkpoint->query_until(
-	qr/starting_checkpoint/,
-	q(\echo starting_checkpoint
-checkpoint;
-\q
-));
+my $checkpoint = PostgreSQL::Test::Session->new(node => $node);
+$checkpoint->do_async(q(CHECKPOINT;));
 
 # Wait until the checkpoint stops right before removing WAL segments.
 note('waiting for injection_point');
@@ -90,17 +83,21 @@ note('injection_point is reached');
 
 # Try to advance the logical slot, but make it stop when it moves to the next
 # WAL segment (this has to happen in the background, too).
-my $logical = $node->background_psql('postgres');
-$logical->query_safe(
+# We need to call pg_logical_slot_get_changes repeatedly until the slot
+# advances to the next segment and hits the injection point.
+my $logical = PostgreSQL::Test::Session->new(node => $node);
+$logical->do(
 	q{select injection_points_attach('logical-replication-slot-advance-segment','wait');}
 );
-$logical->query_until(
-	qr/get_changes/,
-	q(
-\echo get_changes
-select count(*) from pg_logical_slot_get_changes('slot_logical', null, null) \watch 1
-\q
-));
+$logical->do_async(
+	q{DO $$
+	BEGIN
+		LOOP
+			PERFORM count(*) FROM pg_logical_slot_get_changes('slot_logical', null, null);
+			PERFORM pg_sleep(0.1);
+		END LOOP;
+	END $$;}
+);
 
 # Wait until the slot's restart_lsn points to the next WAL segment.
 note('waiting for injection_point');
@@ -138,12 +135,8 @@ eval {
 };
 is($@, '', "Logical slot still valid");
 
-# If we send \q with $<psql_session>->quit the command can be sent to the
-# session already closed. So \q is in initial script, here we only finish
-# IPC::Run
-$xacts->{run}->finish;
-$checkpoint->{run}->finish;
-$logical->{run}->finish;
+# Sessions were terminated by the server crash and will be cleaned up
+# automatically when they go out of scope.
 
 # Verify that the synchronized slots won't be invalidated immediately after
 # synchronization in the presence of a concurrent checkpoint.
@@ -185,15 +178,11 @@ $primary->wait_for_replay_catchup($standby);
 # checkpoint stops right before invalidating replication slots.
 note('starting checkpoint');
 
-$checkpoint = $standby->background_psql('postgres');
-$checkpoint->query_safe(
+$standby->safe_psql('postgres',
 	q(select injection_points_attach('restartpoint-before-slot-invalidation','wait'))
 );
-$checkpoint->query_until(
-	qr/starting_checkpoint/,
-	q(\echo starting_checkpoint
-checkpoint;
-));
+$checkpoint = PostgreSQL::Test::Session->new(node => $standby);
+$checkpoint->do_async(q(CHECKPOINT;));
 
 # Wait until the checkpoint stops right before invalidating slots
 note('waiting for injection_point');
@@ -216,7 +205,8 @@ $standby->safe_psql(
 	q{select injection_points_wakeup('restartpoint-before-slot-invalidation');
 	  select injection_points_detach('restartpoint-before-slot-invalidation')});
 
-$checkpoint->quit;
+$checkpoint->wait_for_completion;
+$checkpoint->close;
 
 # Confirm that the slot is not invalidated
 is( $standby->safe_psql(
diff --git a/src/test/recovery/t/047_checkpoint_physical_slot.pl b/src/test/recovery/t/047_checkpoint_physical_slot.pl
index 4334145abe1..43193c219ba 100644
--- a/src/test/recovery/t/047_checkpoint_physical_slot.pl
+++ b/src/test/recovery/t/047_checkpoint_physical_slot.pl
@@ -8,6 +8,7 @@ use strict;
 use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 
 use Test::More;
@@ -69,16 +70,11 @@ note("restart lsn before checkpoint: $restart_lsn_init");
 # removing old WAL segments.
 note('starting checkpoint');
 
-my $checkpoint = $node->background_psql('postgres');
-$checkpoint->query_safe(
+my $checkpoint = PostgreSQL::Test::Session->new(node => $node);
+$checkpoint->do(
 	q{select injection_points_attach('checkpoint-before-old-wal-removal','wait')}
 );
-$checkpoint->query_until(
-	qr/starting_checkpoint/,
-	q(\echo starting_checkpoint
-checkpoint;
-\q
-));
+$checkpoint->do_async('checkpoint');
 
 # Wait until the checkpoint stops right before removing WAL segments.
 note('waiting for injection_point');
@@ -104,7 +100,11 @@ my $restart_lsn_old = $node->safe_psql('postgres',
 chomp($restart_lsn_old);
 note("restart lsn before stop: $restart_lsn_old");
 
-# Abruptly stop the server.
+$checkpoint->wait_for_completion();
+$checkpoint->close();
+
+# Abruptly stop the server (1 second should be enough for the checkpoint
+# to finish; it would be better).
 $node->stop('immediate');
 
 $node->start;
diff --git a/src/test/recovery/t/048_vacuum_horizon_floor.pl b/src/test/recovery/t/048_vacuum_horizon_floor.pl
index 52acb5561d6..a487be04dc8 100644
--- a/src/test/recovery/t/048_vacuum_horizon_floor.pl
+++ b/src/test/recovery/t/048_vacuum_horizon_floor.pl
@@ -45,12 +45,10 @@ my $orig_conninfo = $node_primary->connstr();
 my $table1 = "vac_horizon_floor_table";
 
 # Long-running Primary Session A
-my $psql_primaryA =
-  $node_primary->background_psql($test_db, on_error_stop => 1);
+my $session_primaryA = PostgreSQL::Test::Session->new(node => $node_primary, dbname => $test_db);
 
 # Long-running Primary Session B
-my $psql_primaryB =
-  $node_primary->background_psql($test_db, on_error_stop => 1);
+my $session_primaryB = PostgreSQL::Test::Session->new(node => $node_primary, dbname => $test_db);
 
 # Our test relies on two rounds of index vacuuming for reasons elaborated
 # later. To trigger two rounds of index vacuuming, we must fill up the
@@ -123,7 +121,7 @@ $node_replica->poll_query_until(
 # Now insert and update a tuple which will be visible to the vacuum on the
 # primary but which will have xmax newer than the oldest xmin on the standby
 # that was recently disconnected.
-my $res = $psql_primaryA->query_safe(
+my $res = $session_primaryA->query(
 	qq[
 		INSERT INTO $table1 VALUES (99);
 		UPDATE $table1 SET col1 = 100 WHERE col1 = 99;
@@ -132,7 +130,7 @@ my $res = $psql_primaryA->query_safe(
 );
 
 # Make sure the UPDATE finished
-like($res, qr/^after_update$/m, "UPDATE occurred on primary session A");
+like($res->{psqlout}, qr/^after_update$/m, "UPDATE occurred on primary session A");
 
 # Open a cursor on the primary whose pin will keep VACUUM from getting a
 # cleanup lock on the first page of the relation. We want VACUUM to be able to
@@ -145,7 +143,7 @@ my $primary_cursor1 = "vac_horizon_floor_cursor1";
 # The first value inserted into the table was a 7, so FETCH FORWARD should
 # return a 7. That's how we know the cursor has a pin.
 # Disable index scans so the cursor pins heap pages and not index pages.
-$res = $psql_primaryB->query_safe(
+$res = $session_primaryB->query(
 	qq[
 	BEGIN;
 	SET enable_bitmapscan = off;
@@ -156,11 +154,11 @@ $res = $psql_primaryB->query_safe(
 	]
 );
 
-is($res, 7, qq[Cursor query returned $res. Expected value 7.]);
+is($res->{psqlout}, 7, qq[Cursor query returned $res->{psqlout}. Expected value 7.]);
 
 # Get the PID of the session which will run the VACUUM FREEZE so that we can
 # use it to filter pg_stat_activity later.
-my $vacuum_pid = $psql_primaryA->query_safe("SELECT pg_backend_pid();");
+my $vacuum_pid = $session_primaryA->query_oneval("SELECT pg_backend_pid();");
 
 # Now start a VACUUM FREEZE on the primary. It will call vacuum_get_cutoffs()
 # and establish values of OldestXmin and GlobalVisState which are newer than
@@ -176,14 +174,8 @@ my $vacuum_pid = $psql_primaryA->query_safe("SELECT pg_backend_pid();");
 # pages of the heap must be processed in order by a single worker to ensure
 # test stability (PARALLEL 0 shouldn't be necessary but guards against the
 # possibility of parallel heap vacuuming).
-$psql_primaryA->{stdin} .= qq[
-		SET maintenance_io_concurrency = 0;
-		VACUUM (VERBOSE, FREEZE, PARALLEL 0) $table1;
-		\\echo VACUUM
-        ];
-
-# Make sure the VACUUM command makes it to the server.
-$psql_primaryA->{run}->pump_nb();
+$session_primaryA->do('SET maintenance_io_concurrency = 0;');
+$session_primaryA->do_async("VACUUM (VERBOSE, FREEZE, PARALLEL 0) $table1;");
 
 # Make sure that the VACUUM has already called vacuum_get_cutoffs() and is
 # just waiting on the lock to start vacuuming. We don't want the standby to
@@ -229,7 +221,7 @@ $node_primary->poll_query_until(
 # expect that a round of index vacuuming has happened and that the vacuum is
 # now waiting for the cursor to release its pin on the last page of the
 # relation.
-$res = $psql_primaryB->query_safe("FETCH $primary_cursor1");
+$res = $session_primaryB->query_oneval("FETCH $primary_cursor1");
 is($res, 7,
 	qq[Cursor query returned $res from second fetch. Expected value 7.]);
 
@@ -243,13 +235,7 @@ $node_primary->poll_query_until(
 	], 't');
 
 # Commit the transaction with the open cursor so that the VACUUM can finish.
-$psql_primaryB->query_until(
-	qr/^commit$/m,
-	qq[
-			COMMIT;
-			\\echo commit
-        ]
-);
+$session_primaryB->do('COMMIT');
 
 # VACUUM proceeds with pruning and does a visibility check on each tuple. In
 # older versions of Postgres, pruning found our final dead tuple
@@ -281,8 +267,8 @@ $node_primary->safe_psql($test_db, "INSERT INTO $table1 VALUES (1);");
 $node_primary->wait_for_catchup($node_replica, 'replay', $primary_lsn);
 
 ## Shut down psqls
-$psql_primaryA->quit;
-$psql_primaryB->quit;
+$session_primaryA->close;
+$session_primaryB->close;
 
 $node_replica->stop();
 $node_primary->stop();
diff --git a/src/test/recovery/t/049_wait_for_lsn.pl b/src/test/recovery/t/049_wait_for_lsn.pl
index bc216064714..9911e5bfa04 100644
--- a/src/test/recovery/t/049_wait_for_lsn.pl
+++ b/src/test/recovery/t/049_wait_for_lsn.pl
@@ -5,6 +5,7 @@ use strict;
 use warnings FATAL => 'all';
 
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -221,20 +222,15 @@ ok($output eq "timeout", "WAIT FOR returns correct status after timeout");
 my $subxact_lsn = $node_primary->safe_psql('postgres',
 	"SELECT pg_current_wal_insert_lsn() + 10000000000");
 my $subxact_appname = 'wait_for_lsn_subxact_cleanup';
-my $subxact_session =
-  $node_primary->background_psql('postgres', on_error_stop => 0);
-$subxact_session->query_until(
-	qr/start/, qq[
-	SET application_name = '$subxact_appname';
-	BEGIN;
-	SAVEPOINT wait_cleanup;
-	\\echo start
-	WAIT FOR LSN '${subxact_lsn}' WITH (MODE 'primary_flush');
-	ROLLBACK TO wait_cleanup;
-	WAIT FOR LSN '${subxact_lsn}'
-		WITH (MODE 'primary_flush', timeout '10ms', no_throw);
-	COMMIT;
-]);
+my $subxact_session = PostgreSQL::Test::Session->new(node => $node_primary);
+# Send the setup statements individually so the first WAIT FOR LSN can be
+# issued asynchronously: it blocks (the target LSN is unreachable) and will
+# be canceled below.
+$subxact_session->do("SET application_name = '$subxact_appname'");
+$subxact_session->do("BEGIN");
+$subxact_session->do("SAVEPOINT wait_cleanup");
+$subxact_session->do_async(
+	"WAIT FOR LSN '${subxact_lsn}' WITH (MODE 'primary_flush')");
 $node_primary->poll_query_until(
 	'postgres',
 	"SELECT count(*) = 1 FROM pg_stat_activity
@@ -248,18 +244,30 @@ my $subxact_cancelled = $node_primary->safe_psql(
 	   AND wait_event = 'WaitForWalFlush'"
 );
 is($subxact_cancelled, 't', "canceled WAIT FOR LSN in subtransaction");
-$subxact_session->quit;
-chomp($subxact_session->{stdout});
+
+# The cancel interrupts the blocking WAIT FOR LSN, leaving the transaction
+# in an aborted state.
+my $subxact_cancel_res = $subxact_session->get_async_result();
 like(
-	$subxact_session->{stderr},
+	$subxact_cancel_res->{error_message},
 	qr/canceling statement due to user request/,
 	"query cancel interrupted WAIT FOR LSN in subtransaction");
-is($subxact_session->{stdout},
+
+# Roll back to the savepoint so a second WAIT FOR LSN can register again in
+# the same backend; with no_throw it returns 'timeout' rather than erroring.
+$subxact_session->do("ROLLBACK TO wait_cleanup");
+my $subxact_timeout = $subxact_session->query_oneval(
+	"WAIT FOR LSN '${subxact_lsn}'
+		WITH (MODE 'primary_flush', timeout '10ms', no_throw)");
+is($subxact_timeout,
 	"timeout", "second WAIT FOR LSN timed out after savepoint rollback");
-unlike(
-	$subxact_session->{stderr},
-	qr/server closed the connection unexpectedly/,
+
+# The backend survived the cancel without disconnecting: the connection is
+# still usable.
+is($subxact_session->query_oneval('SELECT 1'), '1',
 	"WAIT FOR LSN after savepoint rollback did not disconnect");
+$subxact_session->do("COMMIT");
+$subxact_session->close;
 
 # 5. Check mode validation: standby modes error on primary, primary mode errors
 # on standby, and primary_flush works on primary.  Also check that WAIT FOR
@@ -467,10 +475,8 @@ for (my $i = 0; $i < 5; $i++)
 	my $lsn =
 	  $node_primary->safe_psql('postgres',
 		"SELECT pg_current_wal_insert_lsn()");
-	$psql_sessions[$i] = $node_standby->background_psql('postgres');
-	$psql_sessions[$i]->query_until(
-		qr/start/, qq[
-		\\echo start
+	$psql_sessions[$i] = PostgreSQL::Test::Session->new(node => $node_standby);
+	$psql_sessions[$i]->do_async(qq[
 		WAIT FOR LSN '${lsn}';
 		SELECT log_count(${i});
 	]);
@@ -481,7 +487,8 @@ $node_standby->safe_psql('postgres', "SELECT pg_wal_replay_resume();");
 for (my $i = 0; $i < 5; $i++)
 {
 	$node_standby->wait_for_log("count ${i}", $log_offset);
-	$psql_sessions[$i]->quit;
+	$psql_sessions[$i]->wait_for_completion;
+	$psql_sessions[$i]->close;
 }
 
 ok(1, 'multiple standby_replay waiters reported consistent data');
@@ -505,10 +512,8 @@ for (my $i = 0; $i < 5; $i++)
 my @write_sessions;
 for (my $i = 0; $i < 5; $i++)
 {
-	$write_sessions[$i] = $node_standby->background_psql('postgres');
-	$write_sessions[$i]->query_until(
-		qr/start/, qq[
-		\\echo start
+	$write_sessions[$i] = PostgreSQL::Test::Session->new(node => $node_standby);
+	$write_sessions[$i]->do_async(qq[
 		WAIT FOR LSN '$write_lsns[$i]' WITH (MODE 'standby_write', timeout '1d');
 		SELECT log_wait_done('write_done', $i);
 	]);
@@ -527,7 +532,8 @@ resume_walreceiver($node_standby);
 for (my $i = 0; $i < 5; $i++)
 {
 	$node_standby->wait_for_log("write_done $i", $write_log_offset);
-	$write_sessions[$i]->quit;
+	$write_sessions[$i]->wait_for_completion;
+	$write_sessions[$i]->close;
 }
 
 # Verify on standby that WAL was written up to the target LSN
@@ -557,10 +563,8 @@ for (my $i = 0; $i < 5; $i++)
 my @flush_sessions;
 for (my $i = 0; $i < 5; $i++)
 {
-	$flush_sessions[$i] = $node_standby->background_psql('postgres');
-	$flush_sessions[$i]->query_until(
-		qr/start/, qq[
-		\\echo start
+	$flush_sessions[$i] = PostgreSQL::Test::Session->new(node => $node_standby);
+	$flush_sessions[$i]->do_async(qq[
 		WAIT FOR LSN '$flush_lsns[$i]' WITH (MODE 'standby_flush', timeout '1d');
 		SELECT log_wait_done('flush_done', $i);
 	]);
@@ -579,7 +583,8 @@ resume_walreceiver($node_standby);
 for (my $i = 0; $i < 5; $i++)
 {
 	$node_standby->wait_for_log("flush_done $i", $flush_log_offset);
-	$flush_sessions[$i]->quit;
+	$flush_sessions[$i]->wait_for_completion;
+	$flush_sessions[$i]->close;
 }
 
 # Verify on standby that WAL was flushed up to the target LSN
@@ -615,10 +620,8 @@ my @mixed_sessions;
 my @mixed_modes = ('standby_replay', 'standby_write', 'standby_flush');
 for (my $i = 0; $i < 6; $i++)
 {
-	$mixed_sessions[$i] = $node_standby->background_psql('postgres');
-	$mixed_sessions[$i]->query_until(
-		qr/start/, qq[
-		\\echo start
+	$mixed_sessions[$i] = PostgreSQL::Test::Session->new(node => $node_standby);
+	$mixed_sessions[$i]->do_async(qq[
 		WAIT FOR LSN '${mixed_target_lsn}' WITH (MODE '$mixed_modes[$i % 3]', timeout '1d');
 		SELECT log_wait_done('mixed_done', $i);
 	]);
@@ -642,7 +645,8 @@ resume_walreceiver($node_standby);
 for (my $i = 0; $i < 6; $i++)
 {
 	$node_standby->wait_for_log("mixed_done $i", $mixed_log_offset);
-	$mixed_sessions[$i]->quit;
+	$mixed_sessions[$i]->wait_for_completion;
+	$mixed_sessions[$i]->close;
 }
 
 # Verify all modes reached the target LSN
@@ -675,10 +679,8 @@ my $primary_flush_log_offset = -s $node_primary->logfile;
 my @primary_flush_sessions;
 for (my $i = 0; $i < 5; $i++)
 {
-	$primary_flush_sessions[$i] = $node_primary->background_psql('postgres');
-	$primary_flush_sessions[$i]->query_until(
-		qr/start/, qq[
-		\\echo start
+	$primary_flush_sessions[$i] = PostgreSQL::Test::Session->new(node => $node_primary);
+	$primary_flush_sessions[$i]->do_async(qq[
 		WAIT FOR LSN '$primary_flush_lsns[$i]' WITH (MODE 'primary_flush', timeout '1d');
 		SELECT log_wait_done('primary_flush_done', $i);
 	]);
@@ -689,7 +691,8 @@ for (my $i = 0; $i < 5; $i++)
 {
 	$node_primary->wait_for_log("primary_flush_done $i",
 		$primary_flush_log_offset);
-	$primary_flush_sessions[$i]->quit;
+	$primary_flush_sessions[$i]->wait_for_completion;
+	$primary_flush_sessions[$i]->close;
 }
 
 # Verify on primary that WAL was flushed up to the target LSN
@@ -717,10 +720,8 @@ my @wait_modes = ('standby_replay', 'standby_write', 'standby_flush');
 my @wait_sessions;
 for (my $i = 0; $i < 3; $i++)
 {
-	$wait_sessions[$i] = $node_standby->background_psql('postgres');
-	$wait_sessions[$i]->query_until(
-		qr/start/, qq[
-		\\echo start
+	$wait_sessions[$i] = PostgreSQL::Test::Session->new(node => $node_standby);
+	$wait_sessions[$i]->do_async(qq[
 		WAIT FOR LSN '${lsn4}' WITH (MODE '$wait_modes[$i]');
 	]);
 }
@@ -758,12 +759,7 @@ ok($output eq "not in recovery",
 $node_standby->stop;
 $node_primary->stop;
 
-# If we send \q with $session->quit the command can be sent to the session
-# already closed. So \q is in initial script, here we only finish IPC::Run.
-for (my $i = 0; $i < 3; $i++)
-{
-	$wait_sessions[$i]->{run}->finish;
-}
+# Sessions will be cleaned up automatically when they go out of scope.
 
 # 9. Archive-only standby tests: verify standby_write/standby_flush work
 # without a walreceiver.  These exercises the replay-position floor in
@@ -862,18 +858,14 @@ $arc_primary->poll_query_until('postgres',
 # Start background waiters.  With replay paused, target > replay, so they
 # will sleep on WaitLatch.  They can only be woken by the replay-loop
 # WaitLSNWakeup calls.
-my $arc_write_session = $arc_standby->background_psql('postgres');
-$arc_write_session->query_until(
-	qr/start/, qq[
-	\\echo start
+my $arc_write_session = PostgreSQL::Test::Session->new(node => $arc_standby);
+$arc_write_session->do_async(qq[
 	WAIT FOR LSN '${arc_target_lsn2}'
 		WITH (MODE 'standby_write', timeout '1d', no_throw);
 ]);
 
-my $arc_flush_session = $arc_standby->background_psql('postgres');
-$arc_flush_session->query_until(
-	qr/start/, qq[
-	\\echo start
+my $arc_flush_session = PostgreSQL::Test::Session->new(node => $arc_standby);
+$arc_flush_session->do_async(qq[
 	WAIT FOR LSN '${arc_target_lsn2}'
 		WITH (MODE 'standby_flush', timeout '1d', no_throw);
 ]);
@@ -887,15 +879,15 @@ $arc_standby->poll_query_until('postgres',
 # STANDBY_FLUSH waiters as it replays past arc_target_lsn2.
 $arc_standby->safe_psql('postgres', "SELECT pg_wal_replay_resume()");
 
-$arc_write_session->quit;
-$arc_flush_session->quit;
-chomp($arc_write_session->{stdout});
-chomp($arc_flush_session->{stdout});
+my $arc_write_out = $arc_write_session->get_async_result();
+my $arc_flush_out = $arc_flush_session->get_async_result();
+$arc_write_session->close;
+$arc_flush_session->close;
 
-is($arc_write_session->{stdout},
+is($arc_write_out->{psqlout},
 	'success',
 	"standby_write waiter woken by replay on archive-only standby");
-is($arc_flush_session->{stdout},
+is($arc_flush_out->{psqlout},
 	'success',
 	"standby_flush waiter woken by replay on archive-only standby");
 
@@ -1035,10 +1027,8 @@ check_wait_for_lsn_fencepost($rcv_standby, 'standby_flush', $flush_lsn,
 $rcv_primary->safe_psql('postgres',
 	"INSERT INTO rcv_test VALUES (generate_series(200, 210))");
 
-my $boundary_session = $rcv_standby->background_psql('postgres');
-$boundary_session->query_until(
-	qr/start/, qq[
-	\\echo start
+my $boundary_session = PostgreSQL::Test::Session->new(node => $rcv_standby);
+$boundary_session->do_async(qq[
 	WAIT FOR LSN '${replay_lsn_plus}'
 		WITH (MODE 'standby_replay', timeout '1d', no_throw);
 ]);
@@ -1049,9 +1039,9 @@ $rcv_standby->poll_query_until('postgres',
 
 $rcv_standby->safe_psql('postgres', "SELECT pg_wal_replay_resume()");
 resume_walreceiver($rcv_standby);
-$boundary_session->quit;
-chomp($boundary_session->{stdout});
-is($boundary_session->{stdout},
+my $boundary_out = $boundary_session->get_async_result();
+$boundary_session->close;
+is($boundary_out->{psqlout},
 	'success',
 	"standby_replay: waiter at current + 1 wakes when replay advances");
 
@@ -1101,10 +1091,8 @@ $tl_standby2->poll_query_until('postgres',
 	"SELECT pg_get_wal_replay_pause_state() = 'paused'")
   or die "Timed out waiting for tl_standby2 replay to pause";
 
-my $tl_session = $tl_standby2->background_psql('postgres');
-$tl_session->query_until(
-	qr/start/, qq[
-	\\echo start
+my $tl_session = PostgreSQL::Test::Session->new(node => $tl_standby2);
+$tl_session->do_async(qq[
 	WAIT FOR LSN '${tl_target}'
 		WITH (MODE 'standby_replay', timeout '1d', no_throw);
 ]);
@@ -1126,9 +1114,9 @@ $tl_standby2->poll_query_until('postgres',
 	"SELECT received_tli > 1 FROM pg_stat_wal_receiver")
   or die "tl_standby2 did not follow upstream timeline switch";
 
-$tl_session->quit;
-chomp($tl_session->{stdout});
-is($tl_session->{stdout}, 'success',
+my $tl_out = $tl_session->get_async_result();
+$tl_session->close;
+is($tl_out->{psqlout}, 'success',
 	"WAIT FOR LSN survives upstream promotion and timeline switch on cascade standby"
 );
 
diff --git a/src/test/recovery/t/050_redo_segment_missing.pl b/src/test/recovery/t/050_redo_segment_missing.pl
index e07ff0c72fe..b492db44684 100644
--- a/src/test/recovery/t/050_redo_segment_missing.pl
+++ b/src/test/recovery/t/050_redo_segment_missing.pl
@@ -7,6 +7,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -44,15 +45,11 @@ $node->safe_psql('postgres',
 $node->safe_psql('postgres',
 	q{select injection_points_attach('create-checkpoint-run', 'wait')});
 
-# Start a psql session to run the checkpoint in the background and make
+# Start a session to run the checkpoint in the background and make
 # the test wait on the injection point so the checkpoint stops just after
 # it starts.
-my $checkpoint = $node->background_psql('postgres');
-$checkpoint->query_until(
-	qr/starting_checkpoint/,
-	q(\echo starting_checkpoint
-checkpoint;
-));
+my $checkpoint = PostgreSQL::Test::Session->new(node => $node);
+$checkpoint->do_async(q(CHECKPOINT;));
 
 # Wait for the initial point to finish, the checkpointer is still
 # outside its critical section.  Then release to reach the second
@@ -76,7 +73,8 @@ $node->safe_psql('postgres',
 	q{select injection_points_wakeup('create-checkpoint-run')});
 $node->wait_for_log(qr/checkpoint complete/, $log_offset);
 
-$checkpoint->quit;
+$checkpoint->wait_for_completion;
+$checkpoint->close;
 
 # Retrieve the WAL file names for the redo record and checkpoint record.
 my $redo_lsn = $node->safe_psql('postgres',
diff --git a/src/test/recovery/t/051_effective_wal_level.pl b/src/test/recovery/t/051_effective_wal_level.pl
index c862073c34e..5c68949f80c 100644
--- a/src/test/recovery/t/051_effective_wal_level.pl
+++ b/src/test/recovery/t/051_effective_wal_level.pl
@@ -6,6 +6,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -382,20 +383,15 @@ if (   $ENV{enable_injection_points} eq 'yes'
 	test_wal_level($primary, "replica|replica",
 		"effective_wal_level got decreased to 'replica' on primary");
 
-	# Start a psql session to test the case where the activation process is
+	# Start a session to test the case where the activation process is
 	# interrupted.
-	my $psql_create_slot = $primary->background_psql('postgres');
+	my $psql_create_slot = PostgreSQL::Test::Session->new(node => $primary);
 
-	# Start the logical decoding activation process upon creating the logical
-	# slot, but it will wait due to the injection point.
-	$psql_create_slot->query_until(
-		qr/create_slot_canceled/,
-		q(\echo create_slot_canceled
-select injection_points_set_local();
-select injection_points_attach('logical-decoding-activation', 'wait');
-select pg_create_logical_replication_slot('slot_canceled', 'pgoutput');
-\q
-));
+	# Set up the injection point in this session (using set_local so it only
+	# affects this session), then start the slot creation which will block.
+	$psql_create_slot->do(q{select injection_points_set_local()});
+	$psql_create_slot->do(q{select injection_points_attach('logical-decoding-activation', 'wait')});
+	$psql_create_slot->do_async(q{select pg_create_logical_replication_slot('slot_canceled', 'pgoutput')});
 
 	$primary->wait_for_event('client backend', 'logical-decoding-activation');
 	note("injection_point 'logical-decoding-activation' is reached");
@@ -412,6 +408,9 @@ select pg_cancel_backend(pid) from pg_stat_activity where query ~ 'slot_canceled
 	$primary->wait_for_log("aborting logical decoding activation process");
 	test_wal_level($primary, "replica|replica",
 		"the activation process aborted");
+
+	# Clean up the session (the async query was cancelled, so we just close)
+	$psql_create_slot->close;
 }
 
 $primary->stop;
diff --git a/src/test/subscription/t/015_stream.pl b/src/test/subscription/t/015_stream.pl
index ac96bc3f009..41765faea34 100644
--- a/src/test/subscription/t/015_stream.pl
+++ b/src/test/subscription/t/015_stream.pl
@@ -5,6 +5,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -30,18 +31,17 @@ sub test_streaming
 	# Interleave a pair of transactions, each exceeding the 64kB limit.
 	my $offset = 0;
 
-	my $h = $node_publisher->background_psql('postgres', on_error_stop => 0);
+	my $h = PostgreSQL::Test::Session->new(node=>$node_publisher);
 
 	# Check the subscriber log from now on.
 	$offset = -s $node_subscriber->logfile;
 
-	$h->query_safe(
-		q{
-	BEGIN;
-	INSERT INTO test_tab SELECT i, sha256(i::text::bytea) FROM generate_series(3, 5000) s(i);
-	UPDATE test_tab SET b = sha256(b) WHERE mod(a,2) = 0;
-	DELETE FROM test_tab WHERE mod(a,3) = 0;
-	});
+	$h->do(
+		'BEGIN',
+		'INSERT INTO test_tab SELECT i, sha256(i::text::bytea) FROM generate_series(3, 5000) s(i)',
+		'UPDATE test_tab SET b = sha256(b) WHERE mod(a,2) = 0',
+		'DELETE FROM test_tab WHERE mod(a,3) = 0',
+	);
 
 	$node_publisher->safe_psql(
 		'postgres', q{
@@ -51,9 +51,9 @@ sub test_streaming
 	COMMIT;
 	});
 
-	$h->query_safe('COMMIT');
+	$h->do('COMMIT');
 	# errors make the next test fail, so ignore them here
-	$h->quit;
+	$h->close;
 
 	$node_publisher->wait_for_catchup($appname);
 
@@ -211,14 +211,14 @@ $node_subscriber->reload;
 $node_subscriber->safe_psql('postgres', q{SELECT 1});
 
 # Interleave a pair of transactions, each exceeding the 64kB limit.
-my $h = $node_publisher->background_psql('postgres', on_error_stop => 0);
+my $h = PostgreSQL::Test::Session->new(node => $node_publisher);
 
 # Confirm if a deadlock between the leader apply worker and the parallel apply
 # worker can be detected.
 
 my $offset = -s $node_subscriber->logfile;
 
-$h->query_safe(
+$h->do(
 	q{
 BEGIN;
 INSERT INTO test_tab_2 SELECT i FROM generate_series(1, 5000) s(i);
@@ -232,8 +232,8 @@ $node_subscriber->wait_for_log(
 
 $node_publisher->safe_psql('postgres', "INSERT INTO test_tab_2 values(1)");
 
-$h->query_safe('COMMIT');
-$h->quit;
+$h->do('COMMIT');
+$h->close;
 
 $node_subscriber->wait_for_log(qr/ERROR: ( [A-Z0-9]+:)? deadlock detected/,
 	$offset);
@@ -260,7 +260,8 @@ $node_subscriber->safe_psql('postgres',
 # Check the subscriber log from now on.
 $offset = -s $node_subscriber->logfile;
 
-$h->query_safe(
+$h->reconnect;
+$h->do(
 	q{
 BEGIN;
 INSERT INTO test_tab_2 SELECT i FROM generate_series(1, 5000) s(i);
@@ -275,8 +276,8 @@ $node_subscriber->wait_for_log(
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO test_tab_2 SELECT i FROM generate_series(1, 5000) s(i)");
 
-$h->query_safe('COMMIT');
-$h->quit;
+$h->do('COMMIT');
+$h->close;
 
 $node_subscriber->wait_for_log(qr/ERROR: ( [A-Z0-9]+:)? deadlock detected/,
 	$offset);
diff --git a/src/test/subscription/t/035_conflicts.pl b/src/test/subscription/t/035_conflicts.pl
index f23fe6af2a5..8058beeb680 100644
--- a/src/test/subscription/t/035_conflicts.pl
+++ b/src/test/subscription/t/035_conflicts.pl
@@ -4,6 +4,7 @@
 use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Session;
 use PostgreSQL::Test::Utils;
 use Test::More;
 
@@ -455,17 +456,14 @@ if ($injection_points_supported != 0)
 
 	# Start a background session on the publisher node to perform an update and
 	# pause at the injection point.
-	my $pub_session = $node_B->background_psql('postgres');
-	$pub_session->query_until(
-		qr/starting_bg_psql/,
-		q{
-			\echo starting_bg_psql
-			BEGIN;
-			UPDATE tab SET b = 2 WHERE a = 1;
-			PREPARE TRANSACTION 'txn_with_later_commit_ts';
-			COMMIT PREPARED 'txn_with_later_commit_ts';
-		}
+	my $pub_session = PostgreSQL::Test::Session->new(node => $node_B);
+	$pub_session->do(
+		q{BEGIN},
+		q{UPDATE tab SET b = 2 WHERE a = 1},
+		q{PREPARE TRANSACTION 'txn_with_later_commit_ts'}
 	);
+	# COMMIT PREPARED will block on the injection point
+	$pub_session->do_async(q{COMMIT PREPARED 'txn_with_later_commit_ts'});
 
 	# Wait until the backend enters the injection point
 	$node_B->wait_for_event('client backend',
@@ -516,8 +514,9 @@ if ($injection_points_supported != 0)
 		 SELECT injection_points_detach('commit-after-delay-checkpoint');"
 	);
 
-	# Close the background session on the publisher node
-	ok($pub_session->quit, "close publisher session");
+	# Wait for the async query to complete and close the background session
+	$pub_session->wait_for_completion;
+	$pub_session->close;
 
 	# Confirm that the transaction committed
 	$result = $node_B->safe_psql('postgres', 'SELECT * FROM tab WHERE a = 1');
diff --git a/src/test/subscription/t/038_walsnd_shutdown_timeout.pl b/src/test/subscription/t/038_walsnd_shutdown_timeout.pl
index f4ed5d97852..48caf8e3da4 100644
--- a/src/test/subscription/t/038_walsnd_shutdown_timeout.pl
+++ b/src/test/subscription/t/038_walsnd_shutdown_timeout.pl
@@ -8,6 +8,7 @@ use strict;
 use warnings FATAL => 'all';
 use PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
+use PostgreSQL::Test::Session;
 use Test::More;
 use Time::HiRes qw(usleep);
 
@@ -45,7 +46,7 @@ $node_subscriber->wait_for_subscription_sync($node_publisher, 'test_sub');
 
 # Start a background session on the subscriber to run a transaction later
 # that will block the logical apply worker on a lock.
-my $sub_session = $node_subscriber->background_psql('postgres');
+my $sub_session = PostgreSQL::Test::Session->new(node => $node_subscriber);
 
 # Test that when the logical apply worker is blocked on a lock and replication
 # is stalled, shutting down the publisher causes the logical walsender to exit
@@ -53,7 +54,7 @@ my $sub_session = $node_subscriber->background_psql('postgres');
 
 # Cause the logical apply worker to block on a lock by running conflicting
 # transactions on the publisher and subscriber.
-$sub_session->query_safe("BEGIN; INSERT INTO test_tab VALUES (0);");
+$sub_session->do("BEGIN; INSERT INTO test_tab VALUES (0);");
 $node_publisher->safe_psql('postgres', "INSERT INTO test_tab VALUES (0);");
 
 my $log_offset = -s $node_publisher->logfile;
@@ -65,7 +66,7 @@ ok( $node_publisher->log_contains(
 		$log_offset),
 	"walsender exits due to wal_sender_shutdown_timeout");
 
-$sub_session->query_safe("ABORT;");
+$sub_session->do("ABORT;");
 $node_publisher->start;
 $node_publisher->wait_for_catchup('test_sub');
 
@@ -79,7 +80,7 @@ $node_publisher->wait_for_catchup('test_sub');
 
 # Run a transaction on the subscriber that blocks the logical apply worker
 # on a lock.
-$sub_session->query_safe("BEGIN; LOCK TABLE test_tab IN EXCLUSIVE MODE;");
+$sub_session->do("BEGIN; LOCK TABLE test_tab IN EXCLUSIVE MODE;");
 
 # Generate enough data to fill the logical walsender's output buffer.
 $node_publisher->safe_psql('postgres',
@@ -117,7 +118,7 @@ ok( $node_publisher->log_contains(
 	"walsender with full output buffer exits due to wal_sender_shutdown_timeout"
 );
 
-$sub_session->query_safe("ABORT;");
+$sub_session->do("ABORT;");
 
 # The next test depends on Perl's `kill`, which apparently is not
 # portable to Windows.  (It would be nice to use Test::More's `subtest`,
@@ -167,7 +168,7 @@ $node_standby->start;
 # Cause the logical apply worker to block on a lock by running conflicting
 # transactions on the publisher and subscriber, stalling logical replication.
 $node_publisher->wait_for_catchup('test_sub');
-$sub_session->query_safe("BEGIN; LOCK TABLE test_tab IN EXCLUSIVE MODE;");
+$sub_session->do("BEGIN; LOCK TABLE test_tab IN EXCLUSIVE MODE;");
 $node_publisher->safe_psql('postgres', "INSERT INTO test_tab VALUES (-1); ");
 
 # Cause the standby's walreceiver to be blocked with SIGSTOP signal,
@@ -193,7 +194,7 @@ ok( $node_publisher->log_contains(
 );
 
 kill 'CONT', $receiverpid;
-$sub_session->quit;
+$sub_session->close;
 
 $node_subscriber->stop('fast');
 $node_standby->stop('fast');
-- 
2.43.0