logging — Logging facility for PythonPython的日志记录工具

Source code: Lib/logging/__init__.py

Important重要的

This page contains the API reference information. 本页包含API参考信息。For tutorial information and discussion of more advanced topics, see有关教程信息和更高级主题的讨论，请参阅

• Basic Tutorial基础教程

• Advanced Tutorial高级教程

• Logging Cookbook日志记录食谱

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This module defines functions and classes which implement a flexible event logging system for applications and libraries.该模块定义了实现应用程序和库的灵活事件记录系统的函数和类。

The key benefit of having the logging API provided by a standard library module is that all Python modules can participate in logging, so your application log can include your own messages integrated with messages from third-party modules.由标准库模块提供日志API的主要好处是，所有Python模块都可以参与日志记录，因此应用程序日志可以包含您自己的消息，并与来自第三方模块的消息集成。

The module provides a lot of functionality and flexibility. 该模块提供了许多功能和灵活性。If you are unfamiliar with logging, the best way to get to grips with it is to see the tutorials (see the links on the right).如果您不熟悉日志记录，了解它的最好方法是查看教程（请参阅右侧的链接）。

The basic classes defined by the module, together with their functions, are listed below.下面列出了模块定义的基本类及其函数。

• Loggers expose the interface that application code directly uses.记录器公开应用程序代码直接使用的接口。

• Handlers send the log records (created by loggers) to the appropriate destination.处理程序将日志记录（由记录器创建）发送到适当的目标。

• Filters provide a finer grained facility for determining which log records to output.筛选器提供了更细粒度的工具，用于确定要输出的日志记录。

• Formatters specify the layout of log records in the final output.格式化程序指定最终输出中日志记录的布局。

Logger Objects记录器对象

Loggers have the following attributes and methods. 记录器具有以下属性和方法。Note that Loggers should NEVER be instantiated directly, but always through the module-level function logging.getLogger(name). 请注意，不应直接实例化记录器，而应始终通过模块级函数logging.getLogger(name)。Multiple calls to getLogger() with the same name will always return a reference to the same Logger object.使用相同名称多次调用getLogger()将始终返回对同一记录器对象的引用。

The name is potentially a period-separated hierarchical value, like foo.bar.baz (though it could also be just plain foo, for example). 该name可能是一个以句点分隔的分层值，比如foo.bar.baz（不过也可以是普通的foo）。Loggers that are further down in the hierarchical list are children of loggers higher up in the list. 层次列表中较低的记录器是列表中较高的记录器的子级。For example, given a logger with a name of foo, loggers with names of foo.bar, foo.bar.baz, and foo.bam are all descendants of foo. 例如，给定一个名为foo的记录器，名为foo.bar、foo.bar.baz和foo.bam的记录器都是foo的后代。The logger name hierarchy is analogous to the Python package hierarchy, and identical to it if you organise your loggers on a per-module basis using the recommended construction logging.getLogger(__name__). 记录器名称层次结构类似于Python包层次结构，如果您使用推荐的结构logging.getLogger(__name__)按模块组织记录器，则与之相同。That’s because in a module, __name__ is the module’s name in the Python package namespace.这是因为在模块中，__name__是Python包命名空间中的模块名称。

classlogging.Logger

propagate

If this attribute evaluates to true, events logged to this logger will be passed to the handlers of higher level (ancestor) loggers, in addition to any handlers attached to this logger. 如果此属性的计算结果为true，则记录到此记录器的事件将传递给更高级别（祖先）记录器的处理程序，以及连接到此记录器的任何处理程序。Messages are passed directly to the ancestor loggers’ handlers - neither the level nor filters of the ancestor loggers in question are considered.消息直接传递给祖先记录器的处理程序-不考虑所讨论的祖先记录器的级别或筛选器。

If this evaluates to false, logging messages are not passed to the handlers of ancestor loggers.如果计算结果为false，则不会将日志消息传递给祖先记录器的处理程序。

Spelling it out with an example: If the propagate attribute of the logger named A.B.C evaluates to true, any event logged to A.B.C via a method call such as logging.getLogger('A.B.C').error(...) will [subject to passing that logger’s level and filter settings] be passed in turn to any handlers attached to loggers named A.B, A and the root logger, after first being passed to any handlers attached to A.B.C. 举例说明：如果名为A.B.C的记录器的propagate属性计算为true，则通过方法调用记录到ABC的任何事件，如logging.getLogger('A.B.C').error(...)将[根据传递该记录器的级别和筛选器设置]依次传递到名为A.B、A的记录器和根记录器的任何处理程序，然后再传递到任何附加到A.B.C上的处理程序。If any logger in the chain A.B.C, A.B, A has its propagate attribute set to false, then that is the last logger whose handlers are offered the event to handle, and propagation stops at that point.如果链A.B.C、A.B、A中的任何记录器将其传播属性设置为false，则这是向其处理程序提供事件处理的最后一个记录器，传播在该点停止。

The constructor sets this attribute to True.构造函数将此属性设置为True。

Note

If you attach a handler to a logger and one or more of its ancestors, it may emit the same record multiple times. 如果将处理程序连接到记录器及其一个或多个祖先，则它可能会多次发出同一条记录。In general, you should not need to attach a handler to more than one logger - if you just attach it to the appropriate logger which is highest in the logger hierarchy, then it will see all events logged by all descendant loggers, provided that their propagate setting is left set to True. 通常，您不需要将处理程序附加到多个记录器-如果您只是将其附加到记录器层次结构中最高的适当记录器，那么它将看到所有后代记录器记录的所有事件，前提是其传播设置保持为True。A common scenario is to attach handlers only to the root logger, and to let propagation take care of the rest.一种常见的场景是仅将处理程序附加到根记录器，并让传播处理其余部分。

setLevel(level)

Sets the threshold for this logger to level. 将此记录器的阈值设置为level。Logging messages which are less severe than level will be ignored; logging messages which have severity level or higher will be emitted by whichever handler or handlers service this logger, unless a handler’s level has been set to a higher severity level than level.严重程度低于level的日志消息将被忽略；除非已将处理程序的级别设置为比level更高的严重性级别，否则为该记录器提供服务的处理程序将发出严重性级别或更高的日志消息。

When a logger is created, the level is set to NOTSET (which causes all messages to be processed when the logger is the root logger, or delegation to the parent when the logger is a non-root logger). 创建记录器时，级别设置为NOTSET（当记录器为根记录器时，会处理所有消息；当记录器为非根记录器时，会将消息委托给父级）。Note that the root logger is created with level WARNING.请注意，创建根记录器时带有级别WARNING。

The term ‘delegation to the parent’ means that if a logger has a level of NOTSET, its chain of ancestor loggers is traversed until either an ancestor with a level other than NOTSET is found, or the root is reached.术语“委托给父级”意味着，如果记录器具有NOTSET级别，则会遍历其祖先记录器链，直到找到具有NOTSET以外级别的祖先，或到达根。

If an ancestor is found with a level other than NOTSET, then that ancestor’s level is treated as the effective level of the logger where the ancestor search began, and is used to determine how a logging event is handled.如果发现祖先的级别不是NOTSET，则该祖先的级别将被视为祖先搜索开始的记录器的有效级别，并用于确定如何处理日志事件。

If the root is reached, and it has a level of NOTSET, then all messages will be processed. 如果已到达根，并且其级别为NOTSET，则将处理所有消息。Otherwise, the root’s level will be used as the effective level.否则，根级别将用作有效级别。

See Logging Levels for a list of levels.有关级别列表，请参阅日志记录级别。

Changed in version 3.2:版本3.2中更改： The level parameter now accepts a string representation of the level such as ‘INFO’ as an alternative to the integer constants such as INFO. level参数现在接受级别的字符串表示，如“INFO”，作为整数常量（如INFO）的替代。Note, however, that levels are internally stored as integers, and methods such as e.g. getEffectiveLevel() and isEnabledFor() will return/expect to be passed integers.但是，请注意，级别在内部存储为整数，例如getEffectiveLevel()和isEnabledFor()等方法将返回/期望传递整数。

isEnabledFor(level)

Indicates if a message of severity level would be processed by this logger. 指示此记录器是否将处理严重性level的消息。This method checks first the module-level level set by logging.disable(level) and then the logger’s effective level as determined by getEffectiveLevel().该方法首先检查由logging.disable(level)设置的模块级别，然后检查由getEffectiveLevel()确定的记录器的有效级别。

getEffectiveLevel()

Indicates the effective level for this logger. 指示此记录器的有效级别。If a value other than NOTSET has been set using setLevel(), it is returned. 如果使用setLevel()设置了NOTSET以外的值，则返回该值。Otherwise, the hierarchy is traversed towards the root until a value other than NOTSET is found, and that value is returned. 否则，将向根遍历层次结构，直到找到NOTSET以外的值，并返回该值。The value returned is an integer, typically one of logging.DEBUG, logging.INFO etc.返回的值是一个整数，通常是logging.DEBUG、logging.INFO等之一。

getChild(suffix)

Returns a logger which is a descendant to this logger, as determined by the suffix. 返回一个记录器，该记录器是此记录器的后代，由后缀决定。Thus, logging.getLogger('abc').getChild('def.ghi') would return the same logger as would be returned by logging.getLogger('abc.def.ghi'). 因此，logging.getLogger('abc').getChild('def.ghi')将返回与logging.getLogger('abc.def.ghi')返回的相同的记录器。This is a convenience method, useful when the parent logger is named using e.g. __name__ rather than a literal string.这是一种方便的方法，当使用例如__name__而不是文字字符串来命名父记录器时非常有用。

New in version 3.2.版本3.2中新增。

debug(msg, *args, **kwargs)

Logs a message with level DEBUG on this logger. 在此记录器上记录带有级别DEBUG的消息。The msg is the message format string, and the args are the arguments which are merged into msg using the string formatting operator. msg是消息格式字符串，args是使用字符串格式运算符合并到msg中的参数。(Note that this means that you can use keywords in the format string, together with a single dictionary argument.) （请注意，这意味着您可以在格式字符串中使用关键字，以及单个字典参数。）No % formatting operation is performed on msg when no args are supplied.未提供args时，不会对msg执行%格式化操作。

There are four keyword arguments in kwargs which are inspected: exc_info, stack_info, stacklevel and extra.kwargs中有四个关键字参数被检查：exc_info、stack_info，stacklevel和extra。

If exc_info does not evaluate as false, it causes exception information to be added to the logging message. 如果exc_info的计算结果不为false，则会导致将异常信息添加到日志消息中。If an exception tuple (in the format returned by sys.exc_info()) or an exception instance is provided, it is used; otherwise, sys.exc_info() is called to get the exception information.如果提供了异常元组（采用sys.exc_info()返回的格式）或异常实例，则使用它；否则，调用sys.exc_info()以获取异常信息。

The second optional keyword argument is stack_info, which defaults to False. 第二个可选关键字参数是stack_info，默认为False。If true, stack information is added to the logging message, including the actual logging call. 如果为true，则将堆栈信息添加到日志消息中，包括实际的日志调用。Note that this is not the same stack information as that displayed through specifying exc_info: The former is stack frames from the bottom of the stack up to the logging call in the current thread, whereas the latter is information about stack frames which have been unwound, following an exception, while searching for exception handlers.请注意，这与通过指定exc_info显示的堆栈信息不同：前者是从堆栈底部到当前线程中的日志调用的堆栈帧，而后者是关于在搜索异常处理程序时在异常后已展开的堆栈帧的信息。

You can specify stack_info independently of exc_info, e.g. to just show how you got to a certain point in your code, even when no exceptions were raised. 您可以独立于exc_info指定stack_info，例如，仅显示代码中的某一点，即使没有引发异常。The stack frames are printed following a header line which says:堆栈帧按照标题行打印，标题行表示：

Stack (most recent call last):

This mimics the Traceback (most recent call last): which is used when displaying exception frames.这模拟了Traceback（最近调用最后一次）：在显示异常帧时使用。

The third optional keyword argument is stacklevel, which defaults to 1. 第三个可选关键字参数是stacklevel，默认为1。If greater than 1, the corresponding number of stack frames are skipped when computing the line number and function name set in the LogRecord created for the logging event. 如果大于1，则在计算为日志事件创建的LogRecord中设置的行号和函数名时，将跳过相应数量的堆栈帧。This can be used in logging helpers so that the function name, filename and line number recorded are not the information for the helper function/method, but rather its caller. 这可以用于记录帮助程序，以便记录的函数名、文件名和行号不是帮助程序函数/方法的信息，而是其调用方的信息。The name of this parameter mirrors the equivalent one in the warnings module.此参数的名称与warnings模块中的等效名称相同。

The fourth keyword argument is extra which can be used to pass a dictionary which is used to populate the __dict__ of the LogRecord created for the logging event with user-defined attributes. 第四个关键字参数是extra的，可用于传递字典，字典用于使用用户定义的属性填充为日志事件创建的LogRecord的__dict__。These custom attributes can then be used as you like. 然后，可以根据需要使用这些自定义属性。For example, they could be incorporated into logged messages. 例如，它们可以合并到记录的消息中。For example:例如：

FORMAT = '%(asctime)s %(clientip)-15s %(user)-8s %(message)s'
logging.basicConfig(format=FORMAT)
d = {'clientip': '192.168.0.1', 'user': 'fbloggs'}
logger = logging.getLogger('tcpserver')
logger.warning('Protocol problem: %s', 'connection reset', extra=d)

would print something like会打印出这样的东西吗

2006-02-08 22:20:02,165 192.168.0.1 fbloggs  Protocol problem: connection reset

The keys in the dictionary passed in extra should not clash with the keys used by the logging system. extra传递的字典中的键不应与日志系统使用的键冲突。(See the Formatter documentation for more information on which keys are used by the logging system.)（有关日志系统使用哪些键的更多信息，请参阅Formatter程序文档。）

If you choose to use these attributes in logged messages, you need to exercise some care. 如果选择在记录的消息中使用这些属性，则需要格外小心。In the above example, for instance, the Formatter has been set up with a format string which expects ‘clientip’ and ‘user’ in the attribute dictionary of the LogRecord. 例如，在上面的示例中，Formatter是用一个格式字符串设置的，该字符串在日志记录的属性字典中需要“clientip”和“user”。If these are missing, the message will not be logged because a string formatting exception will occur. 如果缺少这些，则不会记录消息，因为将发生字符串格式异常。So in this case, you always need to pass the extra dictionary with these keys.所以在这种情况下，你总是需要用这些键传递extra的字典。

While this might be annoying, this feature is intended for use in specialized circumstances, such as multi-threaded servers where the same code executes in many contexts, and interesting conditions which arise are dependent on this context (such as remote client IP address and authenticated user name, in the above example). 虽然这可能令人恼火，但此功能旨在用于特殊情况，例如多线程服务器，其中在许多上下文中执行相同的代码，并且出现的有趣情况取决于此上下文（例如，在上面的示例中，远程客户端IP地址和经过身份验证的用户名）。In such circumstances, it is likely that specialized Formatters would be used with particular Handlers.在这种情况下，可能会将专门的Formatter与特定的Handler一起使用。

Changed in version 3.2:版本3.2中更改： The stack_info parameter was added.添加了stack_info参数。

Changed in version 3.5:版本3.5中更改： The exc_info parameter can now accept exception instances.exc_info参数现在可以接受异常实例。

Changed in version 3.8:版本3.8中更改： The stacklevel parameter was added.添加了stacklevel参数。

info(msg, *args, **kwargs)

Logs a message with level INFO on this logger. 在此记录器上记录包含级别INFO的消息。The arguments are interpreted as for debug().参数被解释为用于debug()。

warning(msg, *args, **kwargs)

Logs a message with level WARNING on this logger. 在此记录器上记录带有级别WARNING的消息。The arguments are interpreted as for debug().参数被解释为用于debug()。

Note

There is an obsolete method warn which is functionally identical to warning. 有一个过时的方法warn，其功能与warning相同。As warn is deprecated, please do not use it - use warning instead.由于warn已被弃用，请不要使用它，改用warning。

error(msg, *args, **kwargs)

Logs a message with level ERROR on this logger. 在此记录器上记录带有级别ERROR的消息。The arguments are interpreted as for debug().参数被解释为用于debug()。

critical(msg, *args, **kwargs)

Logs a message with level CRITICAL on this logger. 在此记录器上记录具有CRITICAL级别的消息。The arguments are interpreted as for debug().参数被解释为用于debug()。

log(level, msg, *args, **kwargs)

Logs a message with integer level level on this logger. 在此记录器上记录具有整数级别level的消息。The other arguments are interpreted as for debug().其他参数解释为debug()。

exception(msg, *args, **kwargs)

Logs a message with level ERROR on this logger. 在此记录器上记录带有级别ERROR的消息。The arguments are interpreted as for debug(). 参数被解释为用于debug()。Exception info is added to the logging message. 异常信息将添加到日志消息中。This method should only be called from an exception handler.只能从异常处理程序调用此方法。

addFilter(filter)

Adds the specified filter filter to this logger.将指定的筛选器filter添加到此记录器。

removeFilter(filter)

Removes the specified filter filter from this logger.从此记录器中删除指定的筛选器filter。

filter(record)

Apply this logger’s filters to the record and return True if the record is to be processed. 将此记录器的筛选器应用于记录，如果要处理记录，则返回True。The filters are consulted in turn, until one of them returns a false value. 依次查询筛选器，直到其中一个返回false值。If none of them return a false value, the record will be processed (passed to handlers). 如果它们都不返回false值，则记录将被处理（传递给处理程序）。If one returns a false value, no further processing of the record occurs.如果返回false值，则不会对记录进行进一步处理。

addHandler(hdlr)

Adds the specified handler hdlr to this logger.将指定的处理程序hdlr添加到此记录器。

removeHandler(hdlr)

Removes the specified handler hdlr from this logger.从此记录器中删除指定的处理程序hdlr。

findCaller(stack_info=False, stacklevel=1)

Finds the caller’s source filename and line number. 查找调用者的源文件名和行号。Returns the filename, line number, function name and stack information as a 4-element tuple. 将文件名、行号、函数名和堆栈信息作为4元素元组返回。The stack information is returned as None unless stack_info is True.除非stack_info为True，否则堆栈信息返回为None。

The stacklevel parameter is passed from code calling the debug() and other APIs. stacklevel参数是从调用debug()和其他API的代码传递的。If greater than 1, the excess is used to skip stack frames before determining the values to be returned. 如果大于1，则在确定要返回的值之前，使用过量值跳过堆栈帧。This will generally be useful when calling logging APIs from helper/wrapper code, so that the information in the event log refers not to the helper/wrapper code, but to the code that calls it.当从帮助器/包装器代码调用日志API时，这通常很有用，因此事件日志中的信息不是指帮助器/封装器代码，而是指调用它的代码。

handle(record)

Handles a record by passing it to all handlers associated with this logger and its ancestors (until a false value of propagate is found). 通过将记录传递给与此记录器及其祖先关联的所有处理程序来处理记录（直到找到propagate的false值）。This method is used for unpickled records received from a socket, as well as those created locally. 此方法用于从套接字接收的未勾选记录以及本地创建的记录。Logger-level filtering is applied using filter().使用filter()应用记录器级筛选。

makeRecord(name, level, fn, lno, msg, args, exc_info, func=None, extra=None, sinfo=None)

This is a factory method which can be overridden in subclasses to create specialized LogRecord instances.这是一个工厂方法，可以在子类中重写，以创建专门的LogRecord实例。

hasHandlers()

Checks to see if this logger has any handlers configured. 检查此记录器是否配置了任何处理程序。This is done by looking for handlers in this logger and its parents in the logger hierarchy. 这是通过在记录器层次结构中查找此记录器及其父级中的处理程序来完成的。Returns True if a handler was found, else False. 如果找到处理程序，则返回True，否则返回False。The method stops searching up the hierarchy whenever a logger with the ‘propagate’ attribute set to false is found - that will be the last logger which is checked for the existence of handlers.只要发现“传播”属性设置为false的记录器，该方法就会停止在层次结构中搜索-这将是最后一个检查是否存在处理程序的记录器。

New in version 3.2.版本3.2中新增。

Changed in version 3.7:版本3.7中更改： Loggers can now be pickled and unpickled.记录程序现在可以被腌制和拆开。

Logging Levels日志记录级别

The numeric values of logging levels are given in the following table. 下表给出了日志记录级别的数值。These are primarily of interest if you want to define your own levels, and need them to have specific values relative to the predefined levels. 如果您想定义自己的级别，并且需要它们具有相对于预定义级别的特定值，则这些主要是您感兴趣的。If you define a level with the same numeric value, it overwrites the predefined value; the predefined name is lost.如果使用相同的数值定义级别，则会覆盖预定义值；预定义名称丢失。

Level	Numeric value
CRITICAL	50
ERROR	40
WARNING	30
INFO	20
DEBUG	10
NOTSET	0

Handler Objects对象

Handlers have the following attributes and methods. 处理程序具有以下属性和方法。Note that Handler is never instantiated directly; this class acts as a base for more useful subclasses. 注意，Handler从不直接实例化；这个类作为更有用的子类的基础。However, the __init__() method in subclasses needs to call Handler.__init__().但是，子类中的__init__()方法需要调用Handler.__init__()。

classlogging.Handler

__init__(level=NOTSET)

Initializes the Handler instance by setting its level, setting the list of filters to the empty list and creating a lock (using createLock()) for serializing access to an I/O mechanism.通过设置Handler实例的级别、将筛选器列表设置为空列表并创建锁（使用createLock()）来初始化处理程序实例，以串行化对I/O机制的访问。

createLock()

Initializes a thread lock which can be used to serialize access to underlying I/O functionality which may not be threadsafe.初始化线程锁，该线程锁可用于序列化对可能不线程安全的底层I/O功能的访问。

acquire()

Acquires the thread lock created with createLock().获取使用createLock()创建的线程锁。

release()

Releases the thread lock acquired with acquire().释放使用acquire()获取的线程锁。

setLevel(level)

Sets the threshold for this handler to level. 将此处理程序的阈值设置为level。Logging messages which are less severe than level will be ignored. 严重程度低于level的日志记录消息将被忽略。When a handler is created, the level is set to NOTSET (which causes all messages to be processed).创建处理程序时，级别设置为NOTSET（这将导致处理所有消息）。

See Logging Levels for a list of levels.有关级别列表，请参阅日志记录级别。

Changed in version 3.2:版本3.2中更改： The level parameter now accepts a string representation of the level such as ‘INFO’ as an alternative to the integer constants such as INFO.level参数现在接受级别的字符串表示，如“INFO”，作为整数常量（如INFO）的替代。

setFormatter(fmt)

Sets the Formatter for this handler to fmt.将此处理程序的Formatter设置为fmt。

addFilter(filter)

Adds the specified filter filter to this handler.将指定的筛选器filter添加到此处理程序。

removeFilter(filter)

Removes the specified filter filter from this handler.从此处理程序中删除指定的筛选器filter。

filter(record)

Apply this handler’s filters to the record and return True if the record is to be processed. 将此处理程序的筛选器应用于记录，如果要处理记录，则返回True。The filters are consulted in turn, until one of them returns a false value. 依次查询筛选器，直到其中一个返回假值。If none of them return a false value, the record will be emitted. 如果它们都不返回假值，则将发出记录。If one returns a false value, the handler will not emit the record.如果返回false值，则处理程序将不会发出记录。

flush()

Ensure all logging output has been flushed. 确保所有日志输出都已刷新。This version does nothing and is intended to be implemented by subclasses.这个版本什么都不做，打算由子类实现。

close()

Tidy up any resources used by the handler. 整理处理程序使用的任何资源。This version does no output but removes the handler from an internal list of handlers which is closed when shutdown() is called. 此版本不输出，但从处理程序的内部列表中删除处理程序，该列表在调用shutdown()时关闭。Subclasses should ensure that this gets called from overridden close() methods.子类应确保从重写的close()方法调用。

handle(record)

Conditionally emits the specified logging record, depending on filters which may have been added to the handler. 根据可能已添加到处理程序的筛选器，有条件地发出指定的日志记录。Wraps the actual emission of the record with acquisition/release of the I/O thread lock.用I/O线程锁的获取/释放包装记录的实际发出。

handleError(record)

This method should be called from handlers when an exception is encountered during an emit() call. 当在emit()调用期间遇到异常时，应该从处理程序调用此方法。If the module-level attribute raiseExceptions is False, exceptions get silently ignored. This is what is mostly wanted for a logging system - most users will not care about errors in the logging system, they are more interested in application errors. You could, however, replace this with a custom handler if you wish. The specified record is the one which was being processed when the exception occurred. 指定的记录是发生异常时正在处理的记录。(The default value of raiseExceptions is True, as that is more useful during development).

format(record)

Do formatting for a record - if a formatter is set, use it. 对记录进行格式化-如果设置了格式化程序，则使用它。Otherwise, use the default formatter for the module.否则，请使用模块的默认格式化程序。

emit(record)

Do whatever it takes to actually log the specified logging record. 尽一切可能实际记录指定的日志记录。This version is intended to be implemented by subclasses and so raises a NotImplementedError.此版本旨在通过子类实现，因此会引发NotImplementedError。

For a list of handlers included as standard, see logging.handlers.有关作为标准包含的处理程序列表，请参阅logging.handlers。

Formatter Objects对象

Formatter objects have the following attributes and methods. 对象具有以下属性和方法。They are responsible for converting a LogRecord to (usually) a string which can be interpreted by either a human or an external system. 他们负责将LogRecord转换为（通常）可以由人或外部系统解释的字符串。The base Formatter allows a formatting string to be specified. If none is supplied, the default value of '%(message)s' is used, which just includes the message in the logging call. To have additional items of information in the formatted output (such as a timestamp), keep reading.要在格式化输出中包含其他信息项（如时间戳），请继续读取。

A Formatter can be initialized with a format string which makes use of knowledge of the LogRecord attributes - such as the default value mentioned above making use of the fact that the user’s message and arguments are pre-formatted into a LogRecord’s message attribute. This format string contains standard Python %-style mapping keys. See section printf-style String Formatting for more information on string formatting.

The useful mapping keys in a LogRecord are given in the section on LogRecord attributes.

classlogging.Formatter(fmt=None, datefmt=None, style='%', validate=True, *, defaults=None)

Returns a new instance of the Formatter class. The instance is initialized with a format string for the message as a whole, as well as a format string for the date/time portion of a message. 该实例初始化为整个消息的格式字符串，以及消息的日期/时间部分的格式字符串。If no fmt is specified, '%(message)s' is used. If no datefmt is specified, a format is used which is described in the formatTime() documentation.

The style parameter can be one of ‘%’, ‘{’ or ‘$’ and determines how the format string will be merged with its data: using one of %-formatting, str.format() or string.Template. This only applies to the format string fmt (e.g. '%(message)s' or {message}), not to the actual log messages passed to Logger.debug etc; see Using particular formatting styles throughout your application for more information on using {- and $-formatting for log messages.

The defaults parameter can be a dictionary with default values to use in custom fields. For example: logging.Formatter('%(ip)s %(message)s', defaults={"ip": None})

Changed in version 3.2:版本3.2中更改： The style parameter was added.

Changed in version 3.8:版本3.8中更改： The validate parameter was added. Incorrect or mismatched style and fmt will raise a ValueError. For example: logging.Formatter('%(asctime)s - %(message)s', style='{').

Changed in version 3.10:版本3.10中更改： The defaults parameter was added.

format(record)

The record’s attribute dictionary is used as the operand to a string formatting operation. 记录的属性字典用作字符串格式化操作的操作数。Returns the resulting string. Before formatting the dictionary, a couple of preparatory steps are carried out. 返回结果字符串。在格式化字典之前，需要执行几个准备步骤。The message attribute of the record is computed using msg % args. If the formatting string contains '(asctime)', formatTime() is called to format the event time. If there is exception information, it is formatted using formatException() and appended to the message. Note that the formatted exception information is cached in attribute exc_text. This is useful because the exception information can be pickled and sent across the wire, but you should be careful if you have more than one Formatter subclass which customizes the formatting of exception information. In this case, you will have to clear the cached value (by setting the exc_text attribute to None) after a formatter has done its formatting, so that the next formatter to handle the event doesn’t use the cached value, but recalculates it afresh.

If stack information is available, it’s appended after the exception information, using formatStack() to transform it if necessary.

formatTime(record, datefmt=None)

This method should be called from format() by a formatter which wants to make use of a formatted time. This method can be overridden in formatters to provide for any specific requirement, but the basic behavior is as follows: if datefmt (a string) is specified, it is used with time.strftime() to format the creation time of the record. Otherwise, the format ‘%Y-%m-%d %H:%M:%S,uuu’ is used, where the uuu part is a millisecond value and the other letters are as per the time.strftime() documentation. An example time in this format is 2003-01-23 00:29:50,411. The resulting string is returned.

This function uses a user-configurable function to convert the creation time to a tuple. 此函数使用用户可配置函数将创建时间转换为元组。By default, time.localtime() is used; to change this for a particular formatter instance, set the converter attribute to a function with the same signature as time.localtime() or time.gmtime(). To change it for all formatters, for example if you want all logging times to be shown in GMT, set the converter attribute in the Formatter class.

Changed in version 3.3:版本3.3中更改： Previously, the default format was hard-coded as in this example: 2010-09-06 22:38:15,292 where the part before the comma is handled by a strptime format string ('%Y-%m-%d %H:%M:%S'), and the part after the comma is a millisecond value. Because strptime does not have a format placeholder for milliseconds, the millisecond value is appended using another format string, '%s,%03d' — and both of these format strings have been hardcoded into this method. With the change, these strings are defined as class-level attributes which can be overridden at the instance level when desired. The names of the attributes are default_time_format (for the strptime format string) and default_msec_format (for appending the millisecond value).

Changed in version 3.9:版本3.9中更改： The default_msec_format can be None.

formatException(exc_info)

Formats the specified exception information (a standard exception tuple as returned by sys.exc_info()) as a string. This default implementation just uses traceback.print_exception(). The resulting string is returned.

formatStack(stack_info)

Formats the specified stack information (a string as returned by traceback.print_stack(), but with the last newline removed) as a string. This default implementation just returns the input value.这个默认实现只返回输入值。

Filter Objects对象

Filters can be used by Handlers and Loggers for more sophisticated filtering than is provided by levels. The base filter class only allows events which are below a certain point in the logger hierarchy. For example, a filter initialized with ‘A.B’ will allow events logged by loggers ‘A.B’, ‘A.B.C’, ‘A.B.C.D’, ‘A.B.D’ etc. but not ‘A.BB’, ‘B.A.B’ etc. If initialized with the empty string, all events are passed.

classlogging.Filter(name='')

Returns an instance of the Filter class. If name is specified, it names a logger which, together with its children, will have its events allowed through the filter. If name is the empty string, allows every event.

filter(record)

Is the specified record to be logged? 是否要记录指定的记录？Returns zero for no, nonzero for yes. 返回零表示否，非零表示是。If deemed appropriate, the record may be modified in-place by this method.如果认为合适，可通过该方法对记录进行修改。

Note that filters attached to handlers are consulted before an event is emitted by the handler, whereas filters attached to loggers are consulted whenever an event is logged (using debug(), info(), etc.), before sending an event to handlers. This means that events which have been generated by descendant loggers will not be filtered by a logger’s filter setting, unless the filter has also been applied to those descendant loggers.

You don’t actually need to subclass Filter: you can pass any instance which has a filter method with the same semantics.

Changed in version 3.2:版本3.2中更改： You don’t need to create specialized Filter classes, or use other classes with a filter method: you can use a function (or other callable) as a filter. The filtering logic will check to see if the filter object has a filter attribute: if it does, it’s assumed to be a Filter and its filter() method is called. Otherwise, it’s assumed to be a callable and called with the record as the single parameter. The returned value should conform to that returned by filter().

Although filters are used primarily to filter records based on more sophisticated criteria than levels, they get to see every record which is processed by the handler or logger they’re attached to: this can be useful if you want to do things like counting how many records were processed by a particular logger or handler, or adding, changing or removing attributes in the LogRecord being processed. Obviously changing the LogRecord needs to be done with some care, but it does allow the injection of contextual information into logs (see Using Filters to impart contextual information).

LogRecord Objects对象

LogRecord instances are created automatically by the Logger every time something is logged, and can be created manually via makeLogRecord() (for example, from a pickled event received over the wire).

classlogging.LogRecord(name, level, pathname, lineno, msg, args, exc_info, func=None, sinfo=None)

Contains all the information pertinent to the event being logged.

The primary information is passed in msg and args, which are combined using msg % args to create the message field of the record.

Parameters

• name – The name of the logger used to log the event represented by this LogRecord. 用于记录此日志记录所表示事件的记录器的名称。Note that this name will always have this value, even though it may be emitted by a handler attached to a different (ancestor) logger.请注意，该名称将始终具有该值，即使它可能由附加到不同（祖先）记录器的处理程序发出。

• level – The numeric level of the logging event (one of DEBUG, INFO etc.) 日志记录事件的数字级别（调试、信息等之一）Note that this is converted to two attributes of the LogRecord: levelno for the numeric value and levelname for the corresponding level name.请注意，这将转换为日志记录的两个属性：数值的levelno和对应级别名称的levelname。

• pathname – The full pathname of the source file where the logging call was made.进行日志记录调用的源文件的完整路径名。

• lineno – The line number in the source file where the logging call was made.进行日志记录调用的源文件中的行号。

• msg – The event description message, possibly a format string with placeholders for variable data.事件描述消息，可能是带有变量数据占位符的格式字符串。

• args – Variable data to merge into the msg argument to obtain the event description.要合并到msg参数中以获取事件描述的变量数据。

• exc_info – An exception tuple with the current exception information, or None if no exception information is available.包含当前异常信息的异常元组，如果没有可用的异常信息，则为None。

• func – The name of the function or method from which the logging call was invoked.调用日志记录调用的函数或方法的名称。

• sinfo – A text string representing stack information from the base of the stack in the current thread, up to the logging call.一个文本字符串，表示从当前线程中堆栈底部到日志调用的堆栈信息。

getMessage()

Returns the message for this LogRecord instance after merging any user-supplied arguments with the message. If the user-supplied message argument to the logging call is not a string, str() is called on it to convert it to a string. This allows use of user-defined classes as messages, whose __str__ method can return the actual format string to be used.

Changed in version 3.2:版本3.2中更改： The creation of a LogRecord has been made more configurable by providing a factory which is used to create the record. The factory can be set using getLogRecordFactory() and setLogRecordFactory() (see this for the factory’s signature).

This functionality can be used to inject your own values into a LogRecord at creation time. You can use the following pattern:

old_factory = logging.getLogRecordFactory()
def record_factory(*args, **kwargs):
    record = old_factory(*args, **kwargs)
    record.custom_attribute = 0xdecafbad
    return record

logging.setLogRecordFactory(record_factory)

With this pattern, multiple factories could be chained, and as long as they don’t overwrite each other’s attributes or unintentionally overwrite the standard attributes listed above, there should be no surprises.

LogRecord attributes属性

The LogRecord has a number of attributes, most of which are derived from the parameters to the constructor. (Note that the names do not always correspond exactly between the LogRecord constructor parameters and the LogRecord attributes.) These attributes can be used to merge data from the record into the format string. The following table lists (in alphabetical order) the attribute names, their meanings and the corresponding placeholder in a %-style format string.

If you are using {}-formatting (str.format()), you can use {attrname} as the placeholder in the format string. If you are using $-formatting (string.Template), use the form ${attrname}. In both cases, of course, replace attrname with the actual attribute name you want to use.

In the case of {}-formatting, you can specify formatting flags by placing them after the attribute name, separated from it with a colon. For example: a placeholder of {msecs:03d} would format a millisecond value of 4 as 004. Refer to the str.format() documentation for full details on the options available to you.

Attribute name	Format	Description
args	You shouldn’t need to format this yourself.	The tuple of arguments merged into msg to produce message, or a dict whose values are used for the merge (when there is only one argument, and it is a dictionary).
asctime	%(asctime)s	Human-readable time when the LogRecord was created. By default this is of the form ‘2003-07-08 16:49:45,896’ (the numbers after the comma are millisecond portion of the time).
created	%(created)f	Time when the LogRecord was created (as returned by time.time()).
exc_info	You shouldn’t need to format this yourself.	Exception tuple (à la sys.exc_info) or, if no exception has occurred, None.
filename	%(filename)s	Filename portion of pathname.
funcName	%(funcName)s	Name of function containing the logging call.
levelname	%(levelname)s	Text logging level for the message ('DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL').
levelno	%(levelno)s	Numeric logging level for the message (DEBUG, INFO, WARNING, ERROR, CRITICAL).
lineno	%(lineno)d	Source line number where the logging call was issued (if available).
message	%(message)s	The logged message, computed as msg % args. This is set when Formatter.format() is invoked.
module	%(module)s	Module (name portion of filename).
msecs	%(msecs)d	Millisecond portion of the time when the LogRecord was created.
msg	You shouldn’t need to format this yourself.	The format string passed in the original logging call. Merged with args to produce message, or an arbitrary object (see Using arbitrary objects as messages).
name	%(name)s	Name of the logger used to log the call.
pathname	%(pathname)s	Full pathname of the source file where the logging call was issued (if available).
process	%(process)d	Process ID (if available).
processName	%(processName)s	Process name (if available).
relativeCreated	%(relativeCreated)d	Time in milliseconds when the LogRecord was created, relative to the time the logging module was loaded.
stack_info	You shouldn’t need to format this yourself.	Stack frame information (where available) from the bottom of the stack in the current thread, up to and including the stack frame of the logging call which resulted in the creation of this record.
thread	%(thread)d	Thread ID (if available).
threadName	%(threadName)s	Thread name (if available).

Changed in version 3.1:版本3.1中更改： processName was added.

LoggerAdapter Objects

LoggerAdapter instances are used to conveniently pass contextual information into logging calls. For a usage example, see the section on adding contextual information to your logging output.

classlogging.LoggerAdapter(logger, extra)

Returns an instance of LoggerAdapter initialized with an underlying Logger instance and a dict-like object.

process(msg, kwargs)

Modifies the message and/or keyword arguments passed to a logging call in order to insert contextual information. This implementation takes the object passed as extra to the constructor and adds it to kwargs using key ‘extra’. The return value is a (msg, kwargs) tuple which has the (possibly modified) versions of the arguments passed in.

In addition to the above, LoggerAdapter supports the following methods of Logger: debug(), info(), warning(), error(), exception(), critical(), log(), isEnabledFor(), getEffectiveLevel(), setLevel() and hasHandlers(). These methods have the same signatures as their counterparts in Logger, so you can use the two types of instances interchangeably.

Changed in version 3.2:版本3.2中更改： The isEnabledFor(), getEffectiveLevel(), setLevel() and hasHandlers() methods were added to LoggerAdapter. These methods delegate to the underlying logger.

Changed in version 3.6:版本3.6中更改： Attribute manager and method _log() were added, which delegate to the underlying logger and allow adapters to be nested.

Thread Safety

The logging module is intended to be thread-safe without any special work needing to be done by its clients. It achieves this though using threading locks; there is one lock to serialize access to the module’s shared data, and each handler also creates a lock to serialize access to its underlying I/O.

If you are implementing asynchronous signal handlers using the signal module, you may not be able to use logging from within such handlers. This is because lock implementations in the threading module are not always re-entrant, and so cannot be invoked from such signal handlers.

Module-Level Functions

In addition to the classes described above, there are a number of module-level functions.

logging.getLogger(name=None)

Return a logger with the specified name or, if name is None, return a logger which is the root logger of the hierarchy. If specified, the name is typically a dot-separated hierarchical name like ‘a’, ‘a.b’ or ‘a.b.c.d’. Choice of these names is entirely up to the developer who is using logging.

All calls to this function with a given name return the same logger instance. This means that logger instances never need to be passed between different parts of an application.

logging.getLoggerClass()

Return either the standard Logger class, or the last class passed to setLoggerClass(). This function may be called from within a new class definition, to ensure that installing a customized Logger class will not undo customizations already applied by other code. For example:

class MyLogger(logging.getLoggerClass()):
    # ... override behaviour here

logging.getLogRecordFactory()

Return a callable which is used to create a LogRecord.

New in version 3.2.版本3.2中新增。This function has been provided, along with setLogRecordFactory(), to allow developers more control over how the LogRecord representing a logging event is constructed.

See setLogRecordFactory() for more information about the how the factory is called.

logging.debug(msg, *args, **kwargs)

Logs a message with level DEBUG on the root logger. 在根记录器上记录带有级别DEBUG的消息。The msg is the message format string, and the args are the arguments which are merged into msg using the string formatting operator. msg是消息格式字符串，args是使用字符串格式运算符合并到msg中的参数。(Note that this means that you can use keywords in the format string, together with a single dictionary argument.)（请注意，这意味着您可以在格式字符串中使用关键字，以及单个字典参数。）

There are three keyword arguments in kwargs which are inspected: exc_info which, if it does not evaluate as false, causes exception information to be added to the logging message. If an exception tuple (in the format returned by sys.exc_info()) or an exception instance is provided, it is used; otherwise, sys.exc_info() is called to get the exception information.

The second optional keyword argument is stack_info, which defaults to False. If true, stack information is added to the logging message, including the actual logging call. Note that this is not the same stack information as that displayed through specifying exc_info: The former is stack frames from the bottom of the stack up to the logging call in the current thread, whereas the latter is information about stack frames which have been unwound, following an exception, while searching for exception handlers.

You can specify stack_info independently of exc_info, e.g. to just show how you got to a certain point in your code, even when no exceptions were raised. The stack frames are printed following a header line which says:

Stack (most recent call last):

This mimics the Traceback (most recent call last): which is used when displaying exception frames.

The third optional keyword argument is extra which can be used to pass a dictionary which is used to populate the __dict__ of the LogRecord created for the logging event with user-defined attributes. These custom attributes can then be used as you like. For example, they could be incorporated into logged messages. For example:

FORMAT = '%(asctime)s %(clientip)-15s %(user)-8s %(message)s'
logging.basicConfig(format=FORMAT)
d = {'clientip': '192.168.0.1', 'user': 'fbloggs'}
logging.warning('Protocol problem: %s', 'connection reset', extra=d)

would print something like:它会打印出如下内容：

2006-02-08 22:20:02,165 192.168.0.1 fbloggs  Protocol problem: connection reset

The keys in the dictionary passed in extra should not clash with the keys used by the logging system. (See the Formatter documentation for more information on which keys are used by the logging system.)

If you choose to use these attributes in logged messages, you need to exercise some care. In the above example, for instance, the Formatter has been set up with a format string which expects ‘clientip’ and ‘user’ in the attribute dictionary of the LogRecord. If these are missing, the message will not be logged because a string formatting exception will occur. So in this case, you always need to pass the extra dictionary with these keys.

While this might be annoying, this feature is intended for use in specialized circumstances, such as multi-threaded servers where the same code executes in many contexts, and interesting conditions which arise are dependent on this context (such as remote client IP address and authenticated user name, in the above example). In such circumstances, it is likely that specialized Formatters would be used with particular Handlers.

Changed in version 3.2:版本3.2中更改： The stack_info parameter was added.

logging.info(msg, *args, **kwargs)

Logs a message with level INFO on the root logger. The arguments are interpreted as for debug().

logging.warning(msg, *args, **kwargs)

Logs a message with level WARNING on the root logger. The arguments are interpreted as for debug().

Note

There is an obsolete function warn which is functionally identical to warning. As warn is deprecated, please do not use it - use warning instead.

logging.error(msg, *args, **kwargs)

Logs a message with level ERROR on the root logger. The arguments are interpreted as for debug().

logging.critical(msg, *args, **kwargs)

Logs a message with level CRITICAL on the root logger. The arguments are interpreted as for debug().

logging.exception(msg, *args, **kwargs)

Logs a message with level ERROR on the root logger. 在根记录器上记录带有级别ERROR的消息。The arguments are interpreted as for debug(). 参数被解释为用于debug()。Exception info is added to the logging message. 异常信息将添加到日志消息中。This function should only be called from an exception handler.只能从异常处理程序调用此函数。

logging.log(level, msg, *args, **kwargs)

Logs a message with level level on the root logger. The other arguments are interpreted as for debug().

Note

The above module-level convenience functions, which delegate to the root logger, call basicConfig() to ensure that at least one handler is available. Because of this, they should not be used in threads, in versions of Python earlier than 2.7.1 and 3.2, unless at least one handler has been added to the root logger before the threads are started. In earlier versions of Python, due to a thread safety shortcoming in basicConfig(), this can (under rare circumstances) lead to handlers being added multiple times to the root logger, which can in turn lead to multiple messages for the same event.

logging.disable(level=CRITICAL)

Provides an overriding level level for all loggers which takes precedence over the logger’s own level. When the need arises to temporarily throttle logging output down across the whole application, this function can be useful. Its effect is to disable all logging calls of severity level and below, so that if you call it with a value of INFO, then all INFO and DEBUG events would be discarded, whereas those of severity WARNING and above would be processed according to the logger’s effective level. If logging.disable(logging.NOTSET) is called, it effectively removes this overriding level, so that logging output again depends on the effective levels of individual loggers.

Note that if you have defined any custom logging level higher than CRITICAL (this is not recommended), you won’t be able to rely on the default value for the level parameter, but will have to explicitly supply a suitable value.

Changed in version 3.7:版本3.7中更改： The level parameter was defaulted to level CRITICAL. See bpo-28524 for more information about this change.

logging.addLevelName(level, levelName)

Associates level level with text levelName in an internal dictionary, which is used to map numeric levels to a textual representation, for example when a Formatter formats a message. This function can also be used to define your own levels. 此函数也可用于定义您自己的级别。The only constraints are that all levels used must be registered using this function, levels should be positive integers and they should increase in increasing order of severity.唯一的限制是，必须使用此函数注册所有使用的级别，级别应为正整数，并且它们应按严重程度的递增顺序递增。

Note

If you are thinking of defining your own levels, please see the section on Custom Levels.如果您正在考虑定义自己的级别，请参阅自定义级别一节。

logging.getLevelName(level)

Returns the textual or numeric representation of logging level level.

If level is one of the predefined levels CRITICAL, ERROR, WARNING, INFO or DEBUG then you get the corresponding string. If you have associated levels with names using addLevelName() then the name you have associated with level is returned. If a numeric value corresponding to one of the defined levels is passed in, the corresponding string representation is returned.

The level parameter also accepts a string representation of the level such as ‘INFO’. In such cases, this functions returns the corresponding numeric value of the level.

If no matching numeric or string value is passed in, the string ‘Level %s’ % level is returned.

Note

Levels are internally integers (as they need to be compared in the logging logic). 级别是内部整数（因为它们需要在日志逻辑中进行比较）。This function is used to convert between an integer level and the level name displayed in the formatted log output by means of the %(levelname)s format specifier (see LogRecord attributes), and vice versa.

Changed in version 3.4:版本3.4中更改： In Python versions earlier than 3.4, this function could also be passed a text level, and would return the corresponding numeric value of the level. This undocumented behaviour was considered a mistake, and was removed in Python 3.4, but reinstated in 3.4.2 due to retain backward compatibility.

logging.makeLogRecord(attrdict)

Creates and returns a new LogRecord instance whose attributes are defined by attrdict. This function is useful for taking a pickled LogRecord attribute dictionary, sent over a socket, and reconstituting it as a LogRecord instance at the receiving end.

logging.basicConfig(**kwargs)

Does basic configuration for the logging system by creating a StreamHandler with a default Formatter and adding it to the root logger. The functions debug(), info(), warning(), error() and critical() will call basicConfig() automatically if no handlers are defined for the root logger.

This function does nothing if the root logger already has handlers configured, unless the keyword argument force is set to True.如果根记录器已经配置了处理程序，则此函数不执行任何操作，除非关键字参数force设置为True。

Note

This function should be called from the main thread before other threads are started. 在启动其他线程之前，应先从主线程调用此函数。In versions of Python prior to 2.7.1 and 3.2, if this function is called from multiple threads, it is possible (in rare circumstances) that a handler will be added to the root logger more than once, leading to unexpected results such as messages being duplicated in the log.在2.7.1和3.2之前的Python版本中，如果从多个线程调用此函数，则有可能（在极少数情况下）将处理程序多次添加到根记录器，从而导致意外结果，如日志中的消息重复。

The following keyword arguments are supported.支持以下关键字参数。

Format	Description
filename	Specifies that a FileHandler be created, using the specified filename, rather than a StreamHandler.
filemode	If filename is specified, open the file in this mode. Defaults to 'a'.
format	Use the specified format string for the handler. Defaults to attributes levelname, name and message separated by colons.
datefmt	Use the specified date/time format, as accepted by time.strftime().
style	If format is specified, use this style for the format string. One of '%', '{' or '$' for printf-style, str.format() or string.Template respectively. Defaults to '%'.
level	Set the root logger level to the specified level.
stream	Use the specified stream to initialize the StreamHandler. Note that this argument is incompatible with filename - if both are present, a ValueError is raised.
handlers	If specified, this should be an iterable of already created handlers to add to the root logger. Any handlers which don’t already have a formatter set will be assigned the default formatter created in this function. Note that this argument is incompatible with filename or stream - if both are present, a ValueError is raised.
force	If this keyword argument is specified as true, any existing handlers attached to the root logger are removed and closed, before carrying out the configuration as specified by the other arguments.
encoding	If this keyword argument is specified along with filename, its value is used when the FileHandler is created, and thus used when opening the output file.
errors	If this keyword argument is specified along with filename, its value is used when the FileHandler is created, and thus used when opening the output file. If not specified, the value ‘backslashreplace’ is used. Note that if None is specified, it will be passed as such to open(), which means that it will be treated the same as passing ‘errors’.

Changed in version 3.2:版本3.2中更改： The style argument was added.

Changed in version 3.3:版本3.3中更改： The handlers argument was added. Additional checks were added to catch situations where incompatible arguments are specified (e.g. handlers together with stream or filename, or stream together with filename).

Changed in version 3.8:版本3.8中更改： The force argument was added.

Changed in version 3.9:版本3.9中更改： The encoding and errors arguments were added.

logging.shutdown()

Informs the logging system to perform an orderly shutdown by flushing and closing all handlers. This should be called at application exit and no further use of the logging system should be made after this call.

When the logging module is imported, it registers this function as an exit handler (see atexit), so normally there’s no need to do that manually.

logging.setLoggerClass(klass)

Tells the logging system to use the class klass when instantiating a logger. The class should define __init__() such that only a name argument is required, and the __init__() should call Logger.__init__(). This function is typically called before any loggers are instantiated by applications which need to use custom logger behavior. After this call, as at any other time, do not instantiate loggers directly using the subclass: continue to use the logging.getLogger() API to get your loggers.

logging.setLogRecordFactory(factory)

Set a callable which is used to create a LogRecord.

Parameters

factory – The factory callable to be used to instantiate a log record.

New in version 3.2.版本3.2中新增。This function has been provided, along with getLogRecordFactory(), to allow developers more control over how the LogRecord representing a logging event is constructed.

The factory has the following signature:

factory(name, level, fn, lno, msg, args, exc_info, func=None, sinfo=None, **kwargs)

name

The logger name.

level

The logging level (numeric).

fn

The full pathname of the file where the logging call was made.

lno

The line number in the file where the logging call was made.

msg

The logging message.

args

The arguments for the logging message.

exc_info

An exception tuple, or None.

func

The name of the function or method which invoked the logging call.

sinfo

A stack traceback such as is provided by traceback.print_stack(), showing the call hierarchy.

kwargs

Additional keyword arguments.

Module-Level Attributes

logging.lastResort

A “handler of last resort” is available through this attribute. This is a StreamHandler writing to sys.stderr with a level of WARNING, and is used to handle logging events in the absence of any logging configuration. The end result is to just print the message to sys.stderr. This replaces the earlier error message saying that “no handlers could be found for logger XYZ”. If you need the earlier behaviour for some reason, lastResort can be set to None.

New in version 3.2.版本3.2中新增。

Integration with the warnings module

The captureWarnings() function can be used to integrate logging with the warnings module.

logging.captureWarnings(capture)

This function is used to turn the capture of warnings by logging on and off.

If capture is True, warnings issued by the warnings module will be redirected to the logging system. Specifically, a warning will be formatted using warnings.formatwarning() and the resulting string logged to a logger named 'py.warnings' with a severity of WARNING.

If capture is False, the redirection of warnings to the logging system will stop, and warnings will be redirected to their original destinations (i.e. those in effect before captureWarnings(True) was called).

See also

Module logging.config

Configuration API for the logging module.

Module logging.handlers

Useful handlers included with the logging module.

PEP 282 - A Logging System

The proposal which described this feature for inclusion in the Python standard library.

Original Python logging package

This is the original source for the logging package. The version of the package available from this site is suitable for use with Python 1.5.2, 2.1.x and 2.2.x, which do not include the logging package in the standard library.