MDEV-13073. Fixed failing on BB sys_vars.rpl_semi_sync_master_enabled_basic. The issue forced to add up aan argument to THD::THD and THD::init to propagate skip of a mutex locking. The lock could not be released instead as this leads to clear deadlock; the test is received a piece for concurrent ack thread start/stop.bb-10.2-semisync

5 files changed, 654 insertions, 10 deletions

diff --git a/mysql-test/suite/sys_vars/r/rpl_semi_sync_master_enabled_basic.result b/mysql-test/suite/sys_vars/r/rpl_semi_sync_master_enabled_basic.result
index 7454f0b0089..c7a71a01686 100644
--- a/mysql-test/suite/sys_vars/r/rpl_semi_sync_master_enabled_basic.result
+++ b/mysql-test/suite/sys_vars/r/rpl_semi_sync_master_enabled_basic.result
@@ -65,6 +65,612 @@ set global rpl_semi_sync_master_enabled=1e1;
 ERROR 42000: Incorrect argument type to variable 'rpl_semi_sync_master_enabled'
 set global rpl_semi_sync_master_enabled="some text";
 ERROR 42000: Variable 'rpl_semi_sync_master_enabled' can't be set to the value of 'some text'
+connect  con1,localhost,root,,;
+connect  con2,localhost,root,,;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 100 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (100 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 99 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (99 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 98 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (98 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 97 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (97 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 96 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (96 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 95 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (95 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 94 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (94 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 93 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (93 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 92 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (92 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 91 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (91 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 90 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (90 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 89 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (89 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 88 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (88 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 87 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (87 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 86 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (86 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 85 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (85 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 84 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (84 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 83 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (83 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 82 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (82 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 81 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (81 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 80 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (80 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 79 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (79 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 78 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (78 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 77 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (77 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 76 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (76 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 75 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (75 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 74 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (74 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 73 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (73 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 72 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (72 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 71 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (71 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 70 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (70 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 69 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (69 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 68 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (68 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 67 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (67 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 66 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (66 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 65 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (65 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 64 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (64 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 63 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (63 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 62 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (62 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 61 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (61 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 60 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (60 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 59 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (59 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 58 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (58 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 57 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (57 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 56 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (56 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 55 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (55 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 54 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (54 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 53 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (53 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 52 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (52 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 51 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (51 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 50 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (50 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 49 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (49 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 48 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (48 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 47 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (47 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 46 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (46 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 45 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (45 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 44 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (44 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 43 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (43 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 42 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (42 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 41 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (41 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 40 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (40 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 39 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (39 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 38 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (38 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 37 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (37 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 36 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (36 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 35 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (35 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 34 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (34 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 33 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (33 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 32 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (32 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 31 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (31 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 30 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (30 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 29 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (29 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 28 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (28 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 27 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (27 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 26 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (26 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 25 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (25 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 24 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (24 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 23 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (23 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 22 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (22 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 21 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (21 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 20 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (20 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 19 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (19 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 18 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (18 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 17 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (17 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 16 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (16 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 15 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (15 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 14 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (14 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 13 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (13 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 12 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (12 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 11 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (11 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 10 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (10 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 9 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (9 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 8 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (8 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 7 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (7 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 6 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (6 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 5 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (5 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 4 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (4 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 3 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (3 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 2 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (2 + 1) % 2;
+connection con1;
+connection con2;
+connection con1;
+SET @@global.rpl_semi_sync_master_enabled = 1 % 2;
+connection con2;
+SET @@global.rpl_semi_sync_master_enabled = (1 + 1) % 2;
+connection con1;
+connection con2;
+disconnect con1;
+disconnect con2;
+connection default;
+SET @@global.rpl_semi_sync_master_enabled = 1;
 SET @@global.rpl_semi_sync_master_enabled = @start_global_value;
 select @@global.rpl_semi_sync_master_enabled;
 @@global.rpl_semi_sync_master_enabled
diff --git a/mysql-test/suite/sys_vars/t/rpl_semi_sync_master_enabled_basic.test b/mysql-test/suite/sys_vars/t/rpl_semi_sync_master_enabled_basic.test
index da22d0535f4..25524307559 100644
--- a/mysql-test/suite/sys_vars/t/rpl_semi_sync_master_enabled_basic.test
+++ b/mysql-test/suite/sys_vars/t/rpl_semi_sync_master_enabled_basic.test
@@ -51,6 +51,33 @@ set global rpl_semi_sync_master_enabled=1e1;
 --error ER_WRONG_VALUE_FOR_VAR
 set global rpl_semi_sync_master_enabled="some text";
 
+#
+# Test conflicting concurrent setting
+#
+--let $val_saved= `SELECT @@global.rpl_semi_sync_master_enabled`
+connect (con1,localhost,root,,);
+connect (con2,localhost,root,,);
+--let $iter=100
+while ($iter)
+{
+  --connection con1
+  --send_eval SET @@global.rpl_semi_sync_master_enabled = $iter % 2
+
+  --connection con2
+  --send_eval SET @@global.rpl_semi_sync_master_enabled = ($iter + 1) % 2
+
+  --connection con1
+  reap;
+  --connection con2
+  reap;
+
+  --dec $iter
+}
+disconnect con1;
+disconnect con2;
+
+--connection default
+--eval SET @@global.rpl_semi_sync_master_enabled = $val_saved
 
 #
 # Cleanup
diff --git a/sql/semisync_master_ack_receiver.cc b/sql/semisync_master_ack_receiver.cc
index 7240d10b745..6cd02419e37 100644
--- a/sql/semisync_master_ack_receiver.cc
+++ b/sql/semisync_master_ack_receiver.cc
@@ -209,7 +209,8 @@ static void init_net(NET *net, unsigned char *buff, unsigned int buff_len)
 
 void Ack_receiver::run()
 {
-  THD *thd= new THD(next_thread_id());
+  // skip LOCK_global_system_variables due to the 3rd arg
+  THD *thd= new THD(next_thread_id(), false, true);
   NET net;
   unsigned char net_buff[REPLY_MESSAGE_MAX_LENGTH];
 
diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index afd0c375718..a97ad06c7f6 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -693,7 +693,7 @@ extern "C" void thd_kill_timeout(THD* thd)
 }
 
 
-THD::THD(my_thread_id id, bool is_wsrep_applier)
+THD::THD(my_thread_id id, bool is_wsrep_applier, bool skip_global_sys_var_lock)
   :Statement(&main_lex, &main_mem_root, STMT_CONVENTIONAL_EXECUTION,
              /* statement id */ 0),
    rli_fake(0), rgi_fake(0), rgi_slave(NULL),
@@ -880,7 +880,7 @@ THD::THD(my_thread_id id, bool is_wsrep_applier)
   /* Call to init() below requires fully initialized Open_tables_state. */
   reset_open_tables_state(this);
 
-  init();
+  init(skip_global_sys_var_lock);
 #if defined(ENABLED_PROFILING)
   profiling.set_thd(this);
 #endif
@@ -1237,10 +1237,11 @@ extern "C" my_thread_id next_thread_id_noinline()
   Init common variables that has to be reset on start and on change_user
 */
 
-void THD::init(void)
+void THD::init(bool skip_lock)
 {
   DBUG_ENTER("thd::init");
-  mysql_mutex_lock(&LOCK_global_system_variables);
+  if (!skip_lock)
+    mysql_mutex_lock(&LOCK_global_system_variables);
   plugin_thdvar_init(this);
   /*
     plugin_thd_var_init() sets variables= global_system_variables, which
@@ -1253,8 +1254,8 @@ void THD::init(void)
   ::strmake(variables.default_master_connection.str,
             global_system_variables.default_master_connection.str,
             variables.default_master_connection.length);
-
-  mysql_mutex_unlock(&LOCK_global_system_variables);
+  if (!skip_lock)
+    mysql_mutex_unlock(&LOCK_global_system_variables);
 
   user_time.val= start_time= start_time_sec_part= 0;
 
diff --git a/sql/sql_class.h b/sql/sql_class.h
index c0a6f5b0e62..b708b96053f 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -3098,11 +3098,20 @@ public:
   /* Debug Sync facility. See debug_sync.cc. */
   struct st_debug_sync_control *debug_sync_control;
 #endif /* defined(ENABLED_DEBUG_SYNC) */
-  THD(my_thread_id id, bool is_wsrep_applier= false);
+  /**
+    @param id                thread identifier
+    @param is_wsrep_applier  thread type
+    @param skip_lock         instruct whether @c LOCK_global_system_variables
+                             is already locked, to not acquire it then.
+  */
+  THD(my_thread_id id, bool is_wsrep_applier= false, bool skip_lock= false);
 
   ~THD();
-
-  void init(void);
+  /**
+    @param skip_lock         instruct whether @c LOCK_global_system_variables
+                             is already locked, to not acquire it then.
+  */
+  void init(bool skip_lock= false);
   /*
     Initialize memory roots necessary for query processing and (!)
     pre-allocate memory for it. We can't do that in THD constructor because