python yield 和return区别

if '开始分级日志' in message:
            #self.process_id_to_bus_seq.clear()
            #self.gapslist.clear()
            # 记录加到缓存
            #self.gapslist.add(message)
            date_str = datetime.now().strftime("%Y%m%d")
            index_name = 'flink-log-clpf-gaps-' + str(date_str)
            id='0'
            log_event = LogEvent(id, source, fileTag, fileName, serviceCode, appName, timestamp, offset, message, index_name)
            yield log_event.to_dict()
            print('aaaaaaaaaaaaaaaaaaaaaa')
            return
            print('bbbbbbbbbbbbbbbbbbbbbb')


[root@kafka1 pyflink]# python test.py
aaaaaaaaaaaaaaaaaaaaaa
{'id': '0', 'source': '10.4.146.9', 'fileTag': 'gaps', 'fileName': '/opt/test/f3s_20230633_104.log', 'serviceCode': '00000', 'appName': 'clpf', 'timestamp': '1687419610160512025', 'offset': '0', 'message': '2023-06-20 20:04:03.472  

--------------开始分级日志 PID:11493 PROC[MPP_SDS_F3S] DATE:20230620 TIME:200403---------------', 'index_name': 'flink-log-clpf-gaps-20230622'}