Python日志记录不输出任何东西|Python问答

在我正在编写的python脚本中，我试图使用日志记录模块记录事件。我有以下代码来配置记录器：

ERROR_FORMAT = "%(levelname)s at %(asctime)s in %(funcName)s in %(filename) at line %(lineno)d: %(message)s"
DEBUG_FORMAT = "%(lineno)d in %(filename)s at %(asctime)s: %(message)s"
LOG_CONFIG = {'version':1,
              'formatters':{'error':{'format':ERROR_FORMAT},
                            'debug':{'format':DEBUG_FORMAT}},
              'handlers':{'console':{'class':'logging.StreamHandler',
                                     'formatter':'debug',
                                     'level':logging.DEBUG},
                          'file':{'class':'logging.FileHandler',
                                  'filename':'/usr/local/logs/DatabaseUpdate.log',
                                  'formatter':'error',
                                  'level':logging.ERROR}},
              'root':{'handlers':('console', 'file')}}
logging.config.dictConfig(LOG_CONFIG)

当我尝试运行时logging.debug("Some string")，即使文档中的此页面说logging.debug应该由root logger输出消息，我也没有输出到控制台。为什么我的程序什么都不输出，我该如何解决？

默认的日志记录级别是警告。由于您尚未更改级别，因此根记录器的级别仍处于警告状态。这意味着它将忽略任何级别低于警告的日志记录，包括调试日志记录。

本教程对此进行了说明：

import logging
logging.warning('Watch out!') # will print a message to the console
logging.info('I told you so') # will not print anything

“信息”行不打印任何内容，因为级别高于信息。

要更改级别，只需在根记录器中进行设置：

'root':{'handlers':('console', 'file'), 'level':'DEBUG'}

换句话说，仅用level = DEBUG定义处理程序是不够的，实际的日志记录级别也必须是DEBUG才能使其输出任何内容。

许多年后，Python记录器似乎仍然存在可用性问题。以下是一些示例说明：

import logging
# This sets the root logger to write to stdout (your console).
# Your script/app needs to call this somewhere at least once.
logging.basicConfig()

# By default the root logger is set to WARNING and all loggers you define
# inherit that value. Here we set the root logger to NOTSET. This logging
# level is automatically inherited by all existing and new sub-loggers
# that do not set a less verbose level.
logging.root.setLevel(logging.NOTSET)

# The following line sets the root logger level as well.
# It's equivalent to both previous statements combined:
logging.basicConfig(level=logging.NOTSET)


# You can either share the `logger` object between all your files or the
# name handle (here `my-app`) and call `logging.getLogger` with it.
# The result is the same.
handle = "my-app"
logger1 = logging.getLogger(handle)
logger2 = logging.getLogger(handle)
# logger1 and logger2 point to the same object:
# (logger1 is logger2) == True


# Convenient methods in order of verbosity from highest to lowest
logger.debug("this will get printed")
logger.info("this will get printed")
logger.warning("this will get printed")
logger.error("this will get printed")
logger.critical("this will get printed")


# In large applications where you would like more control over the logging,
# create sub-loggers from your main application logger.
component_logger = logger.getChild("component-a")
component_logger.info("this will get printed with the prefix `my-app.component-a`")

# If you wish to control the logging levels, you can set the level anywhere 
# in the hierarchy:
#
# - root
#   - my-app
#     - component-a
#

# Example for development:
logger.setLevel(logging.DEBUG)

# If that prints too much, enable debug printing only for your component:
component_logger.setLevel(logging.DEBUG)


# For production you rather want:
logger.setLevel(logging.WARNING)

混乱的一个常见根源是初始化错误的根记录器。考虑一下：

import logging
log = logging.getLogger("myapp")
log.warning("woot")
logging.basicConfig()
log.warning("woot")

输出：

woot
WARNING:myapp:woot

根据您的运行时环境和日志记录级别，第一条日志行（在基本配置之前）可能不会在任何地方显示。

对于任何想要超级简单答案的人：只需设置要显示的级别即可。在我所有脚本的顶部，我只输入了：

import logging
logging.basicConfig(level = logging.INFO)

然后显示该级别或更高级别的任何内容：

logging.info("Hi you just set your fleeb to level plumbus")

它是由五个级别组成的层次结构，因此日志将以您设置的级别或更高级别显示。因此，如果要显示错误，可以使用logging.error("The plumbus is broken")。

水平，在日益严重的依次是DEBUG，INFO，WARNING，ERROR，和CRITICAL。默认设置为WARNING。

这是一篇很好的文章，包含了比我的回答更好表达的信息：https :
//www.digitalocean.com/community/tutorials/how-to-use-logging-in-python-3

也许试试这个？在我的情况下，删除所有处理程序后，似乎问题已解决。

for handler in logging.root.handlers[:]:
    logging.root.removeHandler(handler)

logging.basicConfig(filename='output.log', level=logging.INFO)

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