mariadb/mysql-test/suite/galera/t/MW-336.test
Daniele Sciascia 364b15c090 MW-336 Avoid slave threads leaking
This patch fixes two problems that may arise when changing the
value of wsrep_slave_threads:

1) Threads may be leaked if wsrep_slave_threads is changed
   repeatedly. Specifically, when changing the number of slave
   threads, we keep track of wsrep_slave_count_change, the
   number of slaves to start / stop. The problem arises when
   wsrep_slave_count_change is updated before slaves had a
   chance to exit (threads may take some time to exit, as they
   exit only after commiting one more replication event).
   The fix is to update wsrep_slave_count_change such that it
   reflects the number of threads that already exited or are
   scheduled to exit.

2) Attempting to set out of range value for wsrep_slave_threads
   (below 1 / above 512) results in wsrep_slave_count_change to
   be computed based on the out of range value, even though a
   warning is generated and wsrep_slave_threads is set to a
   truncated value. wsrep_slave_count_change is computed in
   wsrep_slave_threads_check(), which is called before mysql
   checks for valid range. Fix is to update wsrep_count_change
   whenever wsrep_slave_threads is updated with a valid value.
2017-08-11 12:31:26 +03:00

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#
# MW-336 Slave threads may leak if variable wsrep_slave_threads is set repeatedly
#
--source include/galera_cluster.inc
--source include/have_innodb.inc
CREATE TABLE t1 (f1 INTEGER) Engine=InnoDB;
--connection node_1
SET GLOBAL wsrep_slave_threads = 10;
SET GLOBAL wsrep_slave_threads = 1;
--connection node_2
INSERT INTO t1 VALUES (1);
--connection node_1
--sleep 0.5
SET GLOBAL wsrep_slave_threads = 10;
--sleep 0.5
SELECT COUNT(*) = 11 FROM INFORMATION_SCHEMA.PROCESSLIST WHERE USER = 'system user';
SET GLOBAL wsrep_slave_threads = 20;
--sleep 0.5
SELECT COUNT(*) = 21 FROM INFORMATION_SCHEMA.PROCESSLIST WHERE USER = 'system user';
SET GLOBAL wsrep_slave_threads = 1;
--connection node_2
INSERT INTO t1 VALUES (1);
INSERT INTO t1 VALUES (2);
INSERT INTO t1 VALUES (3);
INSERT INTO t1 VALUES (4);
INSERT INTO t1 VALUES (5);
INSERT INTO t1 VALUES (6);
INSERT INTO t1 VALUES (7);
INSERT INTO t1 VALUES (8);
INSERT INTO t1 VALUES (9);
--connection node_1
SET GLOBAL wsrep_slave_threads = 10;
SET GLOBAL wsrep_slave_threads = 0;
--connection node_2
INSERT INTO t1 VALUES (10);
INSERT INTO t1 VALUES (11);
INSERT INTO t1 VALUES (12);
INSERT INTO t1 VALUES (13);
INSERT INTO t1 VALUES (14);
INSERT INTO t1 VALUES (15);
INSERT INTO t1 VALUES (16);
INSERT INTO t1 VALUES (17);
INSERT INTO t1 VALUES (18);
INSERT INTO t1 VALUES (19);
INSERT INTO t1 VALUES (20);
--connection node_1
--sleep 0.5
SELECT COUNT(*) = 2 FROM INFORMATION_SCHEMA.PROCESSLIST WHERE USER = 'system user';
SET GLOBAL wsrep_slave_threads = 1;
DROP TABLE t1;