import logging  

logging.basicConfig(filename='logger.log', format='%(asctime)s - %(levelname)s - %(message)s',level=logging.INFO)
logger = logging.getLogger(__name__)   	#定義一次就可以，其他地方需要調用logger,只需要直接使用logger就行了
logger.setLevel(level=logging.INFO)  	#定義過濾級別
filehandler = logging.FileHandler("log.txt")  	# Handler用于將日志記錄發送至合適的目的地，如文件、終端等
filehandler.setLevel(logging.INFO)  
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')  
filehandler.setFormatter(formatter)  
  
console = logging.StreamHandler()  		#日志信息顯示在終端terminal
console.setLevel(logging.INFO)  
console.setFormatter(formatter)
  
logger.addHandler(filehandler)  
logger.addHandler(console)  
  
logger.info("Start log")  
logger.debug("Do something")  
logger.warning("Something fail.")  
logger.info("Finish")  

try:
    ........
except Exception as e:
    logger.exception(e)

class Popen(object):
    method = 'fork'

    def __init__(self, process_obj):
        try:
            sys.stdout.flush()
        except (AttributeError, ValueError):
            pass
        try:
            sys.stderr.flush()
        except (AttributeError, ValueError):
            pass
        self.returncode = None
        self._launch(process_obj)