create table t1 (a int, b int);
create table t2 (c int, d int);
insert t1 values (1,2),(3,4);
insert t2 values (5,6),(7,8);
create table t0 (x int);
insert t0 values (11), (22);
create trigger tr1 before update on t1 for each row insert t0 values (new.b);
set debug_sync='open_tables_after_open_and_process_table SIGNAL ready WAIT_FOR cont';
update t1 join t2 on (a=c+4) set b=d;
connect con1, localhost, root;
set debug_sync='now WAIT_FOR ready';
set debug_sync='mdl_acquire_lock_wait SIGNAL cont';
lock table t1 write, t0 write;
disconnect con1;
connection default;
drop table t1, t2, t0;
set debug_sync='reset';