QUERY will shows locks.

select
  object_name,
  object_type,
  session_id,
  type,   -- Type or system/user lock
  lmode,     -- lock mode in which session holds lock
  request,
  block,
  ctime   -- Time since current mode was granted
from
  v$locked_object, all_objects, v$lock
where
  v$locked_object.object_id = all_objects.object_id AND
  v$lock.id1 = all_objects.object_id AND
  v$lock.sid = v$locked_object.session_id
order by
  session_id, ctime desc, object_name
/