create table t1 (f int, key(f)) engine=myisam;
set global kc1.key_buffer_size = 65536;
set debug_sync='assign_key_cache_op_unlock wait_for op_locked';
cache index t1 in kc1;
set debug_sync='assign_key_cache_op_lock signal op_locked wait_for assigned';
cache index t1 in kc1;
Table	Op	Msg_type	Msg_text
test.t1	assign_to_keycache	status	OK
set debug_sync='now signal assigned';
Table	Op	Msg_type	Msg_text
test.t1	assign_to_keycache	status	OK
drop table t1;
set global kc1.key_buffer_size = 0;
set debug_sync='reset';