From 23f722ba8e19ca1a7c2ada9d6e687989b6e8f4d1 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 12 Dec 2016 14:32:09 -0500
Subject: [PATCH] Fix race condition in test_decoding "slot" test.
This test, just added in commit a924c327e, sometimes fails because
the old backend hasn't finished dropping the temporary replication slot
when the new backend looks. Borrow the previously-invented methodology
for waiting for the old process to disappear from pg_stat_activity.
Petr Jelinek
Discussion: https://postgr.es/m/62935e6f-4f1b-c433-e0fa-7f936a38b3e5@2ndquadrant.com
---
contrib/test_decoding/expected/slot.out | 19 ++++++++++++++-----
contrib/test_decoding/sql/slot.sql | 16 ++++++++++++----
2 files changed, 26 insertions(+), 9 deletions(-)
diff --git a/contrib/test_decoding/expected/slot.out b/contrib/test_decoding/expected/slot.out
index 5e6b70ba38..c9171ffa5f 100644
--- a/contrib/test_decoding/expected/slot.out
+++ b/contrib/test_decoding/expected/slot.out
@@ -22,17 +22,26 @@ SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_p', 'test
init
(1 row)
--- reconnect to clean temp slots
-\c
+-- here we want to start a new session and wait till old one is gone
+select pg_backend_pid() as oldpid \gset
+\c -
+do 'declare c int = 0;
+begin
+ while (select count(*) from pg_stat_activity where pid = '
+ :'oldpid'
+ ') > 0 loop c := c + 1; perform pg_stat_clear_snapshot(); end loop;
+ raise log ''slot test looped % times'', c;
+end';
+-- should fail because the temporary slot was dropped automatically
+SELECT pg_drop_replication_slot('regression_slot_t');
+ERROR: replication slot "regression_slot_t" does not exist
+-- permanent slot has survived
SELECT pg_drop_replication_slot('regression_slot_p');
pg_drop_replication_slot
--------------------------
(1 row)
--- should fail because the temporary slot was dropped automatically
-SELECT pg_drop_replication_slot('regression_slot_t');
-ERROR: replication slot "regression_slot_t" does not exist
-- test switching between slots in a session
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot1', 'test_decoding', true);
?column?
diff --git a/contrib/test_decoding/sql/slot.sql b/contrib/test_decoding/sql/slot.sql
index 3b0aecd6a8..5d6d97a9e3 100644
--- a/contrib/test_decoding/sql/slot.sql
+++ b/contrib/test_decoding/sql/slot.sql
@@ -4,14 +4,22 @@ SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_t', 'test
SELECT pg_drop_replication_slot('regression_slot_p');
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_p', 'test_decoding', false);
--- reconnect to clean temp slots
-\c
-
-SELECT pg_drop_replication_slot('regression_slot_p');
+-- here we want to start a new session and wait till old one is gone
+select pg_backend_pid() as oldpid \gset
+\c -
+do 'declare c int = 0;
+begin
+ while (select count(*) from pg_stat_activity where pid = '
+ :'oldpid'
+ ') > 0 loop c := c + 1; perform pg_stat_clear_snapshot(); end loop;
+ raise log ''slot test looped % times'', c;
+end';
-- should fail because the temporary slot was dropped automatically
SELECT pg_drop_replication_slot('regression_slot_t');
+-- permanent slot has survived
+SELECT pg_drop_replication_slot('regression_slot_p');
-- test switching between slots in a session
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot1', 'test_decoding', true);