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https://github.com/timescale/timescaledb.git
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55a7141953
The launcher controls how Timescale DB schedulers for each database are stopped/started both at server start time and if they are started or stopped while the server is running which can happen when, say, an update of the extension is performed. Includes tests for multiple types of behavior within the launcher, but only a mock for the db schedulers which will be dealt with in future commits. This launcher code is mostly in the loader, as such it must remain backwards compatible for the foreseeable future, so significant thought and design has gone into making interactions with this code well defined and consistent so that maintaining backwards compatibility is relatively easy.
350 lines
9.5 KiB
Plaintext
350 lines
9.5 KiB
Plaintext
\c single_2 :ROLE_SUPERUSER
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/*
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* Note on testing: need a couple wrappers that pg_sleep in a loop to wait for changes
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* to appear in pg_stat_activity.
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* Further Note: PG 9.6 changed what appeared in pg_stat_activity, so the launcher doesn't actually show up.
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* we can still test its interactions with its children, but can't test some of the things specific to the launcher.
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* So we've added some bits about the version number as needed.
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*/
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CREATE VIEW worker_counts as SELECT count(*) filter (WHERE application_name = 'TimescaleDB Background Worker Launcher') as launcher,
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count(*) filter (WHERE application_name = 'TimescaleDB Background Worker Scheduler' AND datname = 'single') as single_scheduler,
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count(*) filter (WHERE application_name = 'TimescaleDB Background Worker Scheduler' AND datname = 'single_2') as single_2_scheduler
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FROM pg_stat_activity;
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CREATE FUNCTION wait_worker_counts(launcher_ct INTEGER, scheduler1_ct INTEGER, scheduler2_ct INTEGER) RETURNS BOOLEAN LANGUAGE PLPGSQL AS
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$BODY$
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DECLARE
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r INTEGER;
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BEGIN
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FOR i in 1..10
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LOOP
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SELECT COUNT(*) from worker_counts where (launcher = launcher_ct OR current_setting('server_version_num')::int < 100000)
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AND single_scheduler = scheduler1_ct AND single_2_scheduler=scheduler2_ct into r;
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if(r < 1) THEN
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PERFORM pg_sleep(0.1);
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PERFORM pg_stat_clear_snapshot();
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ELSE
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--We have the correct counts!
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RETURN TRUE;
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END IF;
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END LOOP;
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RETURN FALSE;
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END
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$BODY$;
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/*
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* When we've connected to single_2, we should be able to see the cluster launcher
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* and the scheduler for single in pg_stat_activity
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* but single_2 shouldn't have a scheduler because ext not created yet
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*/
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SELECT wait_worker_counts(1,1,0);
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wait_worker_counts
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--------------------
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t
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(1 row)
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/*Now create the extension in single_2*/
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CREATE EXTENSION timescaledb CASCADE;
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SELECT wait_worker_counts(1,1,1);
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wait_worker_counts
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--------------------
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t
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(1 row)
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DROP DATABASE single;
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/* Now the db_scheduler for single should have disappeared*/
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SELECT wait_worker_counts(1,0,1);
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wait_worker_counts
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--------------------
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t
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(1 row)
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/*Now let's restart the scheduler and make sure our backend_start changed */
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SELECT backend_start as orig_backend_start
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FROM pg_stat_activity
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WHERE application_name = 'TimescaleDB Background Worker Scheduler'
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AND datname = 'single_2' \gset
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/* We'll do this in a txn so that we can see that the worker locks on our txn before continuing*/
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BEGIN;
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SELECT _timescaledb_internal.restart_background_workers();
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restart_background_workers
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----------------------------
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t
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(1 row)
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SELECT wait_worker_counts(1,0,1);
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wait_worker_counts
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--------------------
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t
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(1 row)
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SELECT (backend_start > :'orig_backend_start'::timestamptz) backend_start_changed,
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(wait_event = 'virtualxid') wait_event_changed
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FROM pg_stat_activity
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WHERE application_name = 'TimescaleDB Background Worker Scheduler'
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AND datname = 'single_2';
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backend_start_changed | wait_event_changed
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-----------------------+--------------------
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t | t
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(1 row)
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COMMIT;
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SELECT wait_worker_counts(1,0,1);
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wait_worker_counts
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--------------------
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t
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(1 row)
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SELECT (wait_event IS DISTINCT FROM 'virtualxid') wait_event_changed
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FROM pg_stat_activity
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WHERE application_name = 'TimescaleDB Background Worker Scheduler'
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AND datname = 'single_2';
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wait_event_changed
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--------------------
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t
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(1 row)
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/*Test stop*/
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SELECT _timescaledb_internal.stop_background_workers();
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stop_background_workers
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-------------------------
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t
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(1 row)
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SELECT wait_worker_counts(1,0,0);
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wait_worker_counts
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--------------------
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t
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(1 row)
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/*Make sure it doesn't break if we stop twice in a row*/
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SELECT _timescaledb_internal.stop_background_workers();
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stop_background_workers
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-------------------------
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t
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(1 row)
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SELECT wait_worker_counts(1,0,0);
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wait_worker_counts
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--------------------
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t
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(1 row)
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/*test start*/
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SELECT _timescaledb_internal.start_background_workers();
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start_background_workers
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--------------------------
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t
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(1 row)
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SELECT wait_worker_counts(1,0,1);
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wait_worker_counts
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--------------------
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t
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(1 row)
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/*make sure start is idempotent*/
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SELECT backend_start as orig_backend_start
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FROM pg_stat_activity
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WHERE application_name = 'TimescaleDB Background Worker Scheduler'
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AND datname = 'single_2' \gset
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/* Since we're doing idempotency tests, we're also going to exercise our queue and start 20 times*/
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SELECT _timescaledb_internal.start_background_workers() as start_background_workers, * FROM generate_series(1,20);
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start_background_workers | generate_series
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--------------------------+-----------------
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t | 1
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t | 2
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t | 3
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t | 4
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t | 5
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t | 6
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t | 7
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t | 8
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t | 9
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t | 10
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t | 11
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t | 12
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t | 13
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t | 14
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t | 15
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t | 16
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t | 17
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t | 18
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t | 19
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t | 20
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(20 rows)
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/*Here we're waiting to see if something shows up in pg_stat_activity,
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* so we have to condition our loop in the opposite way. We'll only wait
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* half a second in total as well so that tests don't take too long. */
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CREATE FUNCTION wait_equals(TIMESTAMPTZ) RETURNS BOOLEAN LANGUAGE PLPGSQL AS
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$BODY$
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DECLARE
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r BOOLEAN;
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BEGIN
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FOR i in 1..5
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LOOP
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SELECT (backend_start = $1::timestamptz) backend_start_unchanged
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FROM pg_stat_activity
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WHERE application_name = 'TimescaleDB Background Worker Scheduler'
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AND datname = 'single_2' into r;
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if(r) THEN
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PERFORM pg_sleep(0.1);
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PERFORM pg_stat_clear_snapshot();
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ELSE
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RETURN FALSE;
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END IF;
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END LOOP;
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RETURN TRUE;
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END
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$BODY$;
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select wait_equals(:'orig_backend_start');
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wait_equals
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-------------
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t
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(1 row)
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/*Make sure restart works from stopped worker state*/
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SELECT _timescaledb_internal.stop_background_workers();
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stop_background_workers
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-------------------------
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t
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(1 row)
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SELECT wait_worker_counts(1,0,0);
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wait_worker_counts
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--------------------
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t
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(1 row)
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SELECT _timescaledb_internal.restart_background_workers();
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restart_background_workers
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----------------------------
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t
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(1 row)
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SELECT wait_worker_counts(1,0,1);
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wait_worker_counts
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--------------------
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t
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(1 row)
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/*Make sure drop extension statement restarts the worker and on rollback it keeps running*/
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/*Now let's restart the scheduler and make sure our backend_start changed */
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SELECT backend_start as orig_backend_start
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FROM pg_stat_activity
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WHERE application_name = 'TimescaleDB Background Worker Scheduler'
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AND datname = 'single_2' \gset
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BEGIN;
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DROP EXTENSION timescaledb;
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SELECT wait_worker_counts(1,0,1);
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wait_worker_counts
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--------------------
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t
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(1 row)
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ROLLBACK;
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CREATE FUNCTION wait_greater(TIMESTAMPTZ) RETURNS BOOLEAN LANGUAGE PLPGSQL AS
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$BODY$
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DECLARE
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r BOOLEAN;
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BEGIN
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FOR i in 1..10
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LOOP
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SELECT (backend_start > $1::timestamptz) backend_start_changed
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FROM pg_stat_activity
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WHERE application_name = 'TimescaleDB Background Worker Scheduler'
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AND datname = 'single_2' into r;
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if(NOT r) THEN
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PERFORM pg_sleep(0.1);
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PERFORM pg_stat_clear_snapshot();
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ELSE
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RETURN TRUE;
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END IF;
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END LOOP;
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RETURN FALSE;
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END
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$BODY$;
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SELECT wait_greater(:'orig_backend_start');
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wait_greater
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--------------
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t
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(1 row)
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/* Make sure canceling the launcher backend causes a restart of schedulers */
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SELECT backend_start as orig_backend_start
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FROM pg_stat_activity
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WHERE application_name = 'TimescaleDB Background Worker Scheduler'
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AND datname = 'single_2' \gset
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SELECT coalesce(
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(SELECT pg_cancel_backend(pid) FROM pg_stat_activity WHERE application_name = 'TimescaleDB Background Worker Launcher'),
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(SELECT current_setting('server_version_num')::int < 100000));
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coalesce
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----------
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t
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(1 row)
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SELECT wait_worker_counts(1,0,1);
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wait_worker_counts
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--------------------
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t
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(1 row)
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SELECT ((current_setting('server_version_num')::int < 100000) OR wait_greater(:'orig_backend_start')) as wait_greater;
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wait_greater
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--------------
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t
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(1 row)
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/* Make sure dropping the extension means that the scheduler is stopped*/
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BEGIN;
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DROP EXTENSION timescaledb;
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COMMIT;
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SELECT wait_worker_counts(1,0,0);
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wait_worker_counts
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--------------------
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t
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(1 row)
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/* Make sure terminating the launcher causes it to shut down permanently */
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SELECT coalesce(
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(SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE application_name = 'TimescaleDB Background Worker Launcher'),
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(SELECT current_setting('server_version_num')::int < 100000));
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coalesce
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----------
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t
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(1 row)
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SELECT
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CASE WHEN (current_setting('server_version_num')::int < 100000)
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THEN wait_worker_counts(1,0,0)
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ELSE wait_worker_counts(0,0,0)
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END;
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wait_worker_counts
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--------------------
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t
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(1 row)
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CREATE FUNCTION wait_no_change(launcher_ct INTEGER, scheduler1_ct INTEGER, scheduler2_ct INTEGER) RETURNS BOOLEAN LANGUAGE PLPGSQL AS
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$BODY$
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DECLARE
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r INTEGER;
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BEGIN
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FOR i in 1..10
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LOOP
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SELECT COUNT(*) from worker_counts where launcher = launcher_ct AND single_scheduler = scheduler1_ct AND single_2_scheduler = scheduler2_ct into r;
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if(r = 1) THEN
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PERFORM pg_sleep(0.1);
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PERFORM pg_stat_clear_snapshot();
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ELSE
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RETURN FALSE;
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END IF;
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END LOOP;
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RETURN TRUE;
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END
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$BODY$;
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SELECT wait_no_change(0,0,0);
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wait_no_change
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----------------
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t
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(1 row)
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