In reply to rr2007:
1.) method used in code (1) is when sequence is not waiting for any response from driver end. while in code (2), wait_for_item_done() waits for req.item_done() of driver and after that get_response(rsp) is blocking task used to get response from driver end.
2.) if you are not using randomize, in code(1) before calling start_item(t), fill the data and remove randomization part. In code (2) before send_request(req),fill data in transaction and remove assert() statement too.