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+ | ====== Python Logging 模块使用方法====== | ||
+ | |||
+ | logging模块是Python自带的日志模块,原来一直没怎么用,在GAE里面用logging比较多,后来有个GAE的项目想转到Linux服务器上面,发现logging模块还挺不错的。 | ||
+ | |||
+ | 收集了一些网上的资料,记录如下。 | ||
+ | |||
+ | ===== 1. 简单的将日志打印到屏幕 ===== | ||
+ | <code python> | ||
+ | import logging | ||
+ | |||
+ | logging.debug('This is debug message') | ||
+ | logging.info('This is info message') | ||
+ | logging.warning('This is warning message') | ||
+ | </code> | ||
+ | |||
+ | 屏幕上打印: | ||
+ | <code> | ||
+ | WARNING:root:This is warning message | ||
+ | </code> | ||
+ | |||
+ | 默认情况下,logging将日志打印到屏幕,日志级别为WARNING; | ||
+ | |||
+ | 日志级别大小关系为:CRITICAL > ERROR > WARNING > INFO > DEBUG > NOTSET,当然也可以自己定义日志级别。 | ||
+ | |||
+ | {{:modules:python-logging-levle.png|}} | ||
+ | |||
+ | ===== 2. 使用basicConfig配置logging日志行为===== | ||
+ | <code python> | ||
+ | import logging | ||
+ | |||
+ | logging.basicConfig(level=logging.DEBUG, | ||
+ | format='%(asctime)s %(filename)s[line:%(lineno)d] %(levelname)s %(message)s', | ||
+ | datefmt='%a, %d %b %Y %H:%M:%S', | ||
+ | filename='myapp.log', | ||
+ | filemode='w') | ||
+ | | ||
+ | logging.debug('This is debug message') | ||
+ | logging.info('This is info message') | ||
+ | logging.warning('This is warning message') | ||
+ | </code> | ||
+ | |||
+ | ./myapp.log文件中内容为: | ||
+ | <code> | ||
+ | Sun, 24 May 2009 21:48:54 demo2.py[line:11] DEBUG This is debug message | ||
+ | Sun, 24 May 2009 21:48:54 demo2.py[line:12] INFO This is info message | ||
+ | Sun, 24 May 2009 21:48:54 demo2.py[line:13] WARNING This is warning message | ||
+ | </code> | ||
+ | |||
+ | logging.basicConfig函数各参数: | ||
+ | |||
+ | <code> | ||
+ | filename: 指定日志文件名 | ||
+ | filemode: 和file函数意义相同,指定日志文件的打开模式,'w'或'a' | ||
+ | format: 指定输出的格式和内容,format可以输出很多有用信息,如上例所示: | ||
+ | %(levelno)s: 打印日志级别的数值 | ||
+ | %(levelname)s: 打印日志级别名称 | ||
+ | %(pathname)s: 打印当前执行程序的路径,其实就是sys.argv[0] | ||
+ | %(filename)s: 打印当前执行程序名 | ||
+ | %(funcName)s: 打印日志的当前函数 | ||
+ | %(lineno)d: 打印日志的当前行号 | ||
+ | %(asctime)s: 打印日志的时间 | ||
+ | %(thread)d: 打印线程ID | ||
+ | %(threadName)s: 打印线程名称 | ||
+ | %(process)d: 打印进程ID | ||
+ | %(message)s: 打印日志信息 | ||
+ | datefmt: 指定时间格式,同time.strftime() | ||
+ | level: 设置日志级别,默认为logging.WARNING | ||
+ | stream: 指定将日志的输出流,可以指定输出到sys.stderr,sys.stdout或者文件,默认输出到sys.stderr,当stream和filename同时指定时,stream被忽略 | ||
+ | </code> | ||
+ | |||
+ | ===== 3 将日志信息同时输出到文件和屏幕 ===== | ||
+ | <code> | ||
+ | import logging | ||
+ | |||
+ | logging.basicConfig(level=logging.DEBUG, | ||
+ | format='%(asctime)s %(filename)s[line:%(lineno)d] %(levelname)s %(message)s', | ||
+ | datefmt='%a, %d %b %Y %H:%M:%S', | ||
+ | filename='myapp.log', | ||
+ | filemode='w') | ||
+ | |||
+ | ################################################################################################# | ||
+ | #定义一个StreamHandler,将INFO级别或更高的日志信息打印到标准错误,并将其添加到当前的日志处理对象# | ||
+ | console = logging.StreamHandler() | ||
+ | console.setLevel(logging.INFO) | ||
+ | formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s') | ||
+ | console.setFormatter(formatter) | ||
+ | logging.getLogger('').addHandler(console) | ||
+ | ################################################################################################# | ||
+ | |||
+ | logging.debug('This is debug message') | ||
+ | logging.info('This is info message') | ||
+ | logging.warning('This is warning message') | ||
+ | </code> | ||
+ | |||
+ | 屏幕上打印: | ||
+ | <code> | ||
+ | root : INFO This is info message | ||
+ | root : WARNING This is warning message | ||
+ | </code> | ||
+ | ./myapp.log文件中内容为: | ||
+ | <code> | ||
+ | Sun, 24 May 2009 21:48:54 demo2.py[line:11] DEBUG This is debug message | ||
+ | Sun, 24 May 2009 21:48:54 demo2.py[line:12] INFO This is info message | ||
+ | Sun, 24 May 2009 21:48:54 demo2.py[line:13] WARNING This is warning message | ||
+ | </code> | ||
+ | |||
+ | ===== 4.logging之日志回滚 ===== | ||
+ | |||
+ | <code python> | ||
+ | import logging | ||
+ | from logging.handlers import RotatingFileHandler | ||
+ | |||
+ | ################################################################################################# | ||
+ | #定义一个RotatingFileHandler,最多备份5个日志文件,每个日志文件最大10M | ||
+ | Rthandler = RotatingFileHandler('myapp.log', maxBytes=10*1024*1024,backupCount=5) | ||
+ | Rthandler.setLevel(logging.INFO) | ||
+ | formatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s') | ||
+ | Rthandler.setFormatter(formatter) | ||
+ | logging.getLogger('').addHandler(Rthandler) | ||
+ | ################################################################################################ | ||
+ | </code> | ||
+ | |||
+ | 从上例和本例可以看出,logging有一个日志处理的主对象,其它处理方式都是通过addHandler添加进去的。 | ||
+ | |||
+ | logging的几种handle方式如下: | ||
+ | |||
+ | <code> | ||
+ | logging.StreamHandler: 日志输出到流,可以是sys.stderr、sys.stdout或者文件 | ||
+ | logging.FileHandler: 日志输出到文件 | ||
+ | 日志回滚方式,实际使用时用RotatingFileHandler和TimedRotatingFileHandler | ||
+ | logging.handlers.BaseRotatingHandler | ||
+ | logging.handlers.RotatingFileHandler | ||
+ | logging.handlers.TimedRotatingFileHandler | ||
+ | logging.handlers.SocketHandler: 远程输出日志到TCP/IP sockets | ||
+ | logging.handlers.DatagramHandler: 远程输出日志到UDP sockets | ||
+ | logging.handlers.SMTPHandler: 远程输出日志到邮件地址 | ||
+ | logging.handlers.SysLogHandler: 日志输出到syslog | ||
+ | logging.handlers.NTEventLogHandler: 远程输出日志到Windows NT/2000/XP的事件日志 | ||
+ | logging.handlers.MemoryHandler: 日志输出到内存中的制定buffer | ||
+ | logging.handlers.HTTPHandler: 通过"GET"或"POST"远程输出到HTTP服务器 | ||
+ | |||
+ | </code> | ||
+ | |||
+ | 由于StreamHandler和FileHandler是常用的日志处理方式,所以直接包含在logging模块中,而其他方式则包含在logging.handlers模块中, | ||
+ | 上述其它处理方式的使用请参见python2.5手册! | ||
+ | |||
+ | ===== 5.通过logging.config模块配置日志 ===== | ||
+ | |||
+ | <code> | ||
+ | #logger.conf | ||
+ | ############################################### | ||
+ | [loggers] | ||
+ | keys=root,example01,example02 | ||
+ | [logger_root] | ||
+ | level=DEBUG | ||
+ | handlers=hand01,hand02 | ||
+ | [logger_example01] | ||
+ | handlers=hand01,hand02 | ||
+ | qualname=example01 | ||
+ | propagate=0 | ||
+ | [logger_example02] | ||
+ | handlers=hand01,hand03 | ||
+ | qualname=example02 | ||
+ | propagate=0 | ||
+ | ############################################### | ||
+ | [handlers] | ||
+ | keys=hand01,hand02,hand03 | ||
+ | [handler_hand01] | ||
+ | class=StreamHandler | ||
+ | level=INFO | ||
+ | formatter=form02 | ||
+ | args=(sys.stderr,) | ||
+ | [handler_hand02] | ||
+ | class=FileHandler | ||
+ | level=DEBUG | ||
+ | formatter=form01 | ||
+ | args=('myapp.log', 'a') | ||
+ | [handler_hand03] | ||
+ | class=handlers.RotatingFileHandler | ||
+ | level=INFO | ||
+ | formatter=form02 | ||
+ | args=('myapp.log', 'a', 10*1024*1024, 5) | ||
+ | ############################################### | ||
+ | [formatters] | ||
+ | keys=form01,form02 | ||
+ | [formatter_form01] | ||
+ | format=%(asctime)s %(filename)s[line:%(lineno)d] %(levelname)s %(message)s | ||
+ | datefmt=%a, %d %b %Y %H:%M:%S | ||
+ | [formatter_form02] | ||
+ | format=%(name)-12s: %(levelname)-8s %(message)s | ||
+ | datefmt= | ||
+ | </code> | ||
+ | |||
+ | |||
+ | 上例3: | ||
+ | |||
+ | <code python> | ||
+ | import logging | ||
+ | import logging.config | ||
+ | |||
+ | logging.config.fileConfig("logger.conf") | ||
+ | logger = logging.getLogger("example01") | ||
+ | |||
+ | logger.debug('This is debug message') | ||
+ | logger.info('This is info message') | ||
+ | logger.warning('This is warning message') | ||
+ | </code> | ||
+ | |||
+ | 上例4: | ||
+ | |||
+ | <code python> | ||
+ | import logging | ||
+ | import logging.config | ||
+ | |||
+ | logging.config.fileConfig("logger.conf") | ||
+ | logger = logging.getLogger("example02") | ||
+ | |||
+ | logger.debug('This is debug message') | ||
+ | logger.info('This is info message') | ||
+ | logger.warning('This is warning message') | ||
+ | </code> | ||
+ | ===== 6.logging是线程安全的 ===== | ||
+ | |||
+ | 在多线程环境中,使用logging时不需要额外的线程冲突考虑。 | ||
+ | |||
+ | ===== 关于root logger以及logger的父子关系 ===== | ||
+ | |||
+ | |||
+ | 前面多次提到root logger, 实际上logger实例之间还有父子关系, root logger就是处于最顶层的logger, 它是所有logger的祖先。如下图: | ||
+ | |||
+ | {{:modules:python-logger-root.png|}} | ||
+ | |||
+ | root logger是默认的logger | ||
+ | |||
+ | 如果不创建logger实例, 直接调用logging.debug()、logging.info()logging.warning()、logging.error()、logging.critical()这些函数, | ||
+ | |||
+ | 那么使用的logger就是 root logger, 它可以自动创建,也是单实例的。 | ||
+ | |||
+ | |||
+ | 如何得到root logger | ||
+ | |||
+ | 通过logging.getLogger()或者logging.getLogger("")得到root logger实例。 | ||
+ | |||
+ | |||
+ | 默认的level | ||
+ | |||
+ | root logger默认的level是logging.WARNING | ||
+ | |||
+ | |||
+ | 如何表示父子关系 | ||
+ | |||
+ | logger的name的命名方式可以表示logger之间的父子关系. 比如: | ||
+ | |||
+ | <code python> | ||
+ | parent_logger = logging.getLogger('foo') | ||
+ | child_logger = logging.getLogger('foo.bar') | ||
+ | </code> | ||
+ | |||
+ | 什么是effective level | ||
+ | |||
+ | logger有一个概念,叫effective level。 如果一个logger没有显示地设置level,那么它就用父亲的level。如果父亲也没有显示地设置level, 就用父亲的父亲的level,以此推.... | ||
+ | |||
+ | 最后到达root logger,一定设置过level。默认为logging.WARNING。 | ||
+ | |||
+ | child loggers得到消息后,既把消息分发给它的handler处理,也会传递给所有祖先logger处理, | ||
+ | |||
+ | |||
+ | 来看一个例子 | ||
+ | <code python> | ||
+ | |||
+ | import logging | ||
+ | |||
+ | # 设置root logger | ||
+ | r = logging.getLogger() | ||
+ | ch = logging.StreamHandler() | ||
+ | ch.setLevel(logging.DEBUG) | ||
+ | formatter = logging.Formatter('%(asctime)s - %(levelname)s - %(message)s') | ||
+ | ch.setFormatter(formatter) | ||
+ | r.addHandler(ch) | ||
+ | |||
+ | # 创建一个logger作为父亲 | ||
+ | p = logging.getLogger('foo') | ||
+ | p.setLevel(logging.DEBUG) | ||
+ | ch = logging.StreamHandler() | ||
+ | ch.setLevel(logging.DEBUG) | ||
+ | formatter = logging.Formatter('%(asctime)s - %(message)s') | ||
+ | ch.setFormatter(formatter) | ||
+ | p.addHandler(ch) | ||
+ | |||
+ | # 创建一个孩子logger | ||
+ | c = logging.getLogger('foo.bar') | ||
+ | c.debug('foo') | ||
+ | </code> | ||
+ | |||
+ | 输出如下: | ||
+ | |||
+ | <code> | ||
+ | 2011-08-31 21:04:29,893 - foo | ||
+ | 2011-08-31 21:04:29,893 - DEBUG - foo | ||
+ | </code> | ||
+ | |||
+ | 可见, 孩子logger没有任何handler,所以对消息不做处理。但是它把消息转发给了它的父 | ||
+ | 亲以及root logger。最后输出两条日志。 | ||