作为@offbyone注释,可以将冗余处理程序添加到记录器的同一实例。用于记录的python文档说-
“多次调用具有相同名称的getLogger()将返回对相同记录器对象的引用。”
因此,我们不必担心将实现变成单一实例。
不幸的是,对于与记录器的相同实例相关联的处理程序,情况 。有 可能 是连接重复处理。
例-
复制此代码并将其保存在main.py中
import logging
print ‘inside main.py’, print ‘-‘*50 def logger():
print 'initializing logger....'
logPath = '.'
fileName = 'temp'
# configure log formatter
logFormatter = logging.Formatter("%(asctime)s [%(filename)s] [%(funcName)s] [%(levelname)s] [%(lineno)d] %(message)s")
# configure file handler
fileHandler = logging.FileHandler("{0}/{1}.log".format(logPath, fileName))
fileHandler.setFormatter(logFormatter)
# configure stream handler
consoleHandler = logging.StreamHandler()
consoleHandler.setFormatter(logFormatter)
# get the logger instance
logger = logging.getLogger(__name__)
# set the logging level
logger.setLevel(logging.DEBUG)
print 'adding handlers- '
#if not len(logger.handlers):
logger.addHandler(fileHandler)
logger.addHandler(consoleHandler)
print 'logger initialized....\n'
print 'associated handlers - ', len(logger.handlers)
for handler in logger.handlers:
print handler
print
return logger
main_logger = logger() main_logger.info(‘utilizing main.py logger.’) print ‘exiting main.py’, print ‘-‘*50
以及sub.py中的以下代码
print 'inside sub.py',
print ‘-‘50 print ‘importing main.py’ import main print ‘imported main.py’ import logging print ‘getting logger instance in sub’ sub_logger = main.logger() print ‘got logger instance in sub’ sub_logger.info(“utilizing sub_logger”) print ‘exiting sub.py’, print ‘-‘50
运行sub.py
narayan@y510p:~/code/so$ python sub.py
inside sub.py -------------------------------------------------- importing main.py inside main.py -------------------------------------------------- initializing logger.... adding handlers- logger initialized....
associated handlers - 2
2015-08-04 07:41:01,824 [main.py] [
associated handlers - 4 # <===== 4 handlers (duplicates added)
got logger instance in sub 2015-08-04 07:41:01,824 [sub.py] [
因此,对返回相同记录器的方法的多次调用增加了重复的处理程序。
现在,对于您的问题-
有什么办法可以检查处理程序是否已经存在
就在这里-
logger.handlers
返回与给定的关联的所有处理程序的列表logger
。
在将处理程序添加到记录器实例之前,请确保不要在main.py中添加重复的处理程序,只需取消注释表示的行if not len(logger.handlers):
并正确缩进以下两行:
if not len(logger.handlers):
logger.addHandler(fileHandler)
logger.addHandler(consoleHandler)
现在再次运行sub.py
narayan@y510p:~/code/so$ python sub.py
inside sub.py --------------------------------------------------
importing main.py
inside main.py --------------------------------------------------
initializing logger....
adding handlers-
logger initialized....
associated handlers - 2
<logging.FileHandler object at 0x7fd67a891c90>
<logging.StreamHandler object at 0x7fd67a862b10>
2015-08-04 08:14:45,620 [main.py] [<module>] [INFO] [41] utilizing main.py logger.
exiting main.py --------------------------------------------------
imported main.py
getting logger instance in sub
initializing logger....
adding handlers-
logger initialized....
associated handlers - 2 # <===== Still 2 handlers (no duplicates)
<logging.FileHandler object at 0x7fd67a891c90>
<logging.StreamHandler object at 0x7fd67a862b10>
got logger instance in sub
2015-08-04 08:14:45,620 [sub.py] [<module>] [INFO] [10] utilizing sub_logger
exiting sub.py --------------------------------------------------
此外,如果您想限制要添加到logger实例中的处理程序的类型,则可以执行以下操作:
print 'adding handlers- '
# allows to add only one instance of file handler and stream handler
if len(logger.handlers) > 0:
print 'making sure we do not add duplicate handlers'
for handler in logger.handlers:
# add the handlers to the logger
# makes sure no duplicate handlers are added
if not isinstance(handler, logging.FileHandler) and not isinstance(handler, logging.StreamHandler):
logger.addHandler(fileHandler)
print 'added file handler'
logger.addHandler(consoleHandler)
print 'added stream handler'
else:
logger.addHandler(fileHandler)
logger.addHandler(consoleHandler)
print 'added handlers for the first time'
希望这可以帮助!
编辑:
不幸的是,对于与记录器的相同实例相关联的处理程序,情况 。有 可能 是连接重复处理。
事实证明,上述说法并不完全正确。
假设我们已经在主模块中创建并配置了一个名为 “ main_logger” 的记录器(仅配置记录器,不返回任何内容)。
# get the logger instance
logger = logging.getLogger("main_logger")
# configuration follows
...
现在在子模块中,如果我们按照命名层次 “ main_logger.sub_module_logger” 创建子记录器,则无需在子模块中对其进行配置。只需按照命名层次创建记录器就足够了。
# get the logger instance
logger = logging.getLogger("main_logger.sub_module_logger")
# no configuration needed
# it inherits the configuration from the parent logger
...
而且它也不会添加重复的处理程序。
参考-在多个模块中使用日志