connection node_1;
CREATE TABLE t1 (id INT PRIMARY KEY) ENGINE=InnoDB;
INSERT INTO t1 VALUES (1);
connection node_2;
SET session wsrep_sync_wait=0;
FLUSH TABLES WITH READ LOCK;
connection node_1;
ALTER TABLE t1 ADD COLUMN f2 INTEGER;
INSERT INTO t1 VALUES (2,3);
connection node_2a;
SET session wsrep_sync_wait=0;
SHOW CREATE TABLE t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `id` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
SET debug_sync='flush_tables_with_read_lock_after_acquire_locks SIGNAL parked2 WAIT_FOR go2';
FLUSH TABLES t1 WITH READ LOCK;;
connection node_2;
SET debug_sync='now WAIT_FOR parked2';
SET debug_sync='now SIGNAL go2';
UNLOCK TABLES;
SHOW CREATE TABLE t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `id` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
connection node_2a;
set debug_sync= 'RESET';
UNLOCK TABLES;
SET SESSION wsrep_sync_wait = DEFAULT;
SHOW CREATE TABLE t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `id` int(11) NOT NULL,
  `f2` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
SELECT * from t1;
id	f2
1	NULL
2	3
connection node_1;
DROP TABLE t1;