src/test/isolation2/expected/resource_queue.out

0:CREATE RESOURCE QUEUE rq_concurrency_test WITH (active_statements = 1);
CREATE
0:CREATE role role_concurrency_test RESOURCE QUEUE rq_concurrency_test;
CREATE

1:SET role role_concurrency_test;
SET
1:BEGIN;
BEGIN
1:DECLARE c1 CURSOR FOR SELECT 1;
DECLARE

2:SET role role_concurrency_test;
SET
2:PREPARE fooplan AS SELECT 1;
PREPARE
2&:EXECUTE fooplan;  <waiting ...>

-- EXECUTE statement(cached plan) will be blocked when the concurrency limit of the resource queue is reached.
0:SELECT rsqcountvalue FROM gp_toolkit.gp_resqueue_status WHERE rsqname='rq_concurrency_test';
 rsqcountvalue 
---------------
 1             
(1 row)
0:SELECT wait_event_type, wait_event from pg_stat_activity where query = 'EXECUTE fooplan;';
 wait_event_type | wait_event    
-----------------+---------------
 ResourceQueue   | ResourceQueue 
(1 row)

-- This should also block.
--
-- We used to have a bug during 9.6 merge where selecting from pg_locks caused
-- a crash, because we didn't set all the fields in the PROCLOCK struct
-- correctly. That only manifested when there were two queries blocked.
3:SET role role_concurrency_test;
SET
3:PREPARE fooplan AS SELECT 1;
PREPARE
3&:EXECUTE fooplan;  <waiting ...>

-- Check pg_stat_activity and pg_locks.
0:SELECT wait_event_type, wait_event from pg_stat_activity where query = 'EXECUTE fooplan;';
 wait_event_type | wait_event    
-----------------+---------------
 ResourceQueue   | ResourceQueue 
 ResourceQueue   | ResourceQueue 
(2 rows)
0:SELECT granted, locktype, mode FROM pg_locks where locktype = 'resource queue' and pid != pg_backend_pid();
 granted | locktype       | mode          
---------+----------------+---------------
 f       | resource queue | ExclusiveLock 
 t       | resource queue | ExclusiveLock 
 f       | resource queue | ExclusiveLock 
(3 rows)

1:END;
END

2<:  <... completed>
 ?column? 
----------
 1        
(1 row)
2:END;
END

3<:  <... completed>
 ?column? 
----------
 1        
(1 row)
3:END;
END

-- Sanity check: Ensure that all locks were released.
0:SELECT granted, locktype, mode FROM pg_locks where locktype = 'resource queue' and pid != pg_backend_pid();
 granted | locktype | mode 
---------+----------+------
(0 rows)

-- Sanity check: Ensure that the resource queue is now empty.
0: SELECT rsqcountlimit, rsqcountvalue from pg_resqueue_status WHERE rsqname = 'rq_concurrency_test';
 rsqcountlimit | rsqcountvalue 
---------------+---------------
 1             | 0             
(1 row)

-- Introduce a holdable cursor.
4:SET role role_concurrency_test;
SET
4:DECLARE c_hold CURSOR WITH HOLD FOR SELECT 1;
DECLARE

-- Sanity check: The holdable cursor should be accounted for in pg_locks.
0:SELECT granted, locktype, mode FROM pg_locks where locktype = 'resource queue' and pid != pg_backend_pid();
 granted | locktype       | mode          
---------+----------------+---------------
 t       | resource queue | ExclusiveLock 
(1 row)

4:CLOSE c_hold;
CLOSE

-- Sanity check: Ensure that all locks were released.
0:SELECT granted, locktype, mode FROM pg_locks where locktype = 'resource queue' and pid != pg_backend_pid();
 granted | locktype | mode 
---------+----------+------
(0 rows)

-- Sanity check: Ensure that the resource queue is now empty.
0: SELECT rsqcountlimit, rsqcountvalue from pg_resqueue_status WHERE rsqname = 'rq_concurrency_test';
 rsqcountlimit | rsqcountvalue 
---------------+---------------
 1             | 0             
(1 row)

0:DROP role role_concurrency_test;
DROP
0:DROP RESOURCE QUEUE rq_concurrency_test;
DROP