code: public void read_unlock_frames(Job job) {
        Frame tr = train();
        if( tr != null ) tr.unlock(job._key,false);
        if( _valid != null && !_train.equals(_valid) )
          valid().unlock(job._key,false);
      }
docs: Read-UnLock both training and validation User frames.  This method is
  called on crashing cleanup pathes, so handles the case where the frames
  are not actually locked.