1SET @save_slave_parallel_threads= @@GLOBAL.slave_parallel_threads;
2SELECT IF(COUNT(*) < 20, "OK", CONCAT("Found too many system user processes: ", COUNT(*))) FROM information_schema.processlist WHERE user = "system user";
3IF(COUNT(*) < 20, "OK", CONCAT("Found too many system user processes: ", COUNT(*)))
4OK
5SELECT @@GLOBAL.slave_parallel_threads as 'must be 20 because of .cnf';
6must be 20 because of .cnf
720
8SELECT @@SESSION.slave_parallel_threads  as 'no session var';
9ERROR HY000: Variable 'slave_parallel_threads' is a GLOBAL variable
10SET GLOBAL slave_parallel_threads= 0;
11SET GLOBAL slave_parallel_threads= DEFAULT;
12SELECT @@GLOBAL.slave_parallel_threads as 'must be 0 because of default';
13must be 0 because of default
140
15SET GLOBAL slave_parallel_threads= 10;
16SELECT @@GLOBAL.slave_parallel_threads;
17@@GLOBAL.slave_parallel_threads
1810
19SELECT IF(COUNT(*) < 10, "OK", CONCAT("Found too many system user processes: ", COUNT(*))) FROM information_schema.processlist WHERE user = "system user";
20IF(COUNT(*) < 10, "OK", CONCAT("Found too many system user processes: ", COUNT(*)))
21OK
22SET GLOBAL slave_parallel_threads = @save_slave_parallel_threads;
23