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Fix race condition in test_decoding "slot" test.

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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
This commit is contained in:
Tom Lane 2016-12-12 14:32:09 -05:00
parent b4630e01fd
commit 23f722ba8e
2 changed files with 26 additions and 9 deletions
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19
contrib/test_decoding/expected/slot.out
View File

@ -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?

16
contrib/test_decoding/sql/slot.sql
View File

@ -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);