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 <ul>
<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate">logging</code> — Logging facility for Python</a><ul>
<li><a class="reference internal" href="#logger-objects">Logger Objects</a></li>
<li><a class="reference internal" href="#logging-levels">Logging Levels</a></li>
<li><a class="reference internal" href="#handler-objects">Handler Objects</a></li>
<li><a class="reference internal" href="#formatter-objects">Formatter Objects</a></li>
<li><a class="reference internal" href="#filter-objects">Filter Objects</a></li>
<li><a class="reference internal" href="#logrecord-objects">LogRecord Objects</a></li>
<li><a class="reference internal" href="#logrecord-attributes">LogRecord attributes</a></li>
<li><a class="reference internal" href="#loggeradapter-objects">LoggerAdapter Objects</a></li>
<li><a class="reference internal" href="#thread-safety">Thread Safety</a></li>
<li><a class="reference internal" href="#module-level-functions">Module-Level Functions</a></li>
<li><a class="reference internal" href="#module-level-attributes">Module-Level Attributes</a></li>
<li><a class="reference internal" href="#integration-with-the-warnings-module">Integration with the warnings module</a></li>
</ul>
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 <li class="nav-item nav-item-this"><a href=""><code class="xref py py-mod docutils literal notranslate">logging</code> — Logging facility for Python</a></li>
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 <section id="module-logging">
<h1><a class="reference internal" href="#module-logging" title="logging: Flexible event logging system for applications."><code class="xref py py-mod docutils literal notranslate">logging</code></a> — Logging facility for Python<a class="headerlink" href="#module-logging" title="Link to this heading">¶</a></h1>
Source code: <a class="reference external" href="https://github.com/python/cpython/tree/3.12/Lib/logging/__init__.py">Lib/logging/__init__.py</a>
<aside class="sidebar" id="index-0">
Important
This page contains the API reference information. For tutorial
information and discussion of more advanced topics, see
<ul class="simple">
<li><a class="reference internal" href="../howto/logging.html#logging-basic-tutorial">Basic Tutorial</a></li>
<li><a class="reference internal" href="../howto/logging.html#logging-advanced-tutorial">Advanced Tutorial</a></li>
<li><a class="reference internal" href="../howto/logging-cookbook.html#logging-cookbook">Logging Cookbook</a></li>
</ul>
</aside>
<hr class="docutils" />
This module defines functions and classes which implement a flexible event
logging system for applications and libraries.
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.
Here’s a simple example of idiomatic usage:
<div class="highlight-python3 notranslate"><div class="highlight"><pre># myapp.py
import logging
import mylib
logger = logging.getLogger(__name__)

def main():
 logging.basicConfig(filename=&#39;myapp.log&#39;, level=logging.INFO)
 logger.info(&#39;Started&#39;)
 mylib.do_something()
 logger.info(&#39;Finished&#39;)

if __name__ == &#39;__main__&#39;:
 main()
</pre></div>
</div>
<div class="highlight-python3 notranslate"><div class="highlight"><pre># mylib.py
import logging
logger = logging.getLogger(__name__)

def do_something():
 logger.info(&#39;Doing something&#39;)
</pre></div>
</div>
If you run myapp.py, you should see this in myapp.log:
<div class="highlight-none notranslate"><div class="highlight"><pre>INFO:__main__:Started
INFO:mylib:Doing something
INFO:__main__:Finished
</pre></div>
</div>
The key feature of this idiomatic usage is that the majority of code is simply
creating a module level logger with <code class="docutils literal notranslate">getLogger(__name__)</code>, and using that
logger to do any needed logging. This is concise, while allowing downstream
code fine-grained control if needed. Logged messages to the module-level logger
get forwarded to handlers of loggers in higher-level modules, all the way up to
the highest-level logger known as the root logger; this approach is known as
hierarchical logging.
For logging to be useful, it needs to be configured: setting the levels and
destinations for each logger, potentially changing how specific modules log,
often based on command-line arguments or application configuration. In most
cases, like the one above, only the root logger needs to be so configured, since
all the lower level loggers at module level eventually forward their messages to
its handlers. <a class="reference internal" href="#logging.basicConfig" title="logging.basicConfig"><code class="xref py py-func docutils literal notranslate">basicConfig()</code></a> provides a quick way to configure
the root logger that handles many use cases.
The module provides a lot of functionality and flexibility. If you are
unfamiliar with logging, the best way to get to grips with it is to view the
tutorials (see the links above and on the right).
The basic classes defined by the module, together with their attributes and
methods, are listed in the sections below.
<ul class="simple">
<li>Loggers expose the interface that application code directly uses.</li>
<li>Handlers send the log records (created by loggers) to the appropriate
destination.</li>
<li>Filters provide a finer grained facility for determining which log records
to output.</li>
<li>Formatters specify the layout of log records in the final output.</li>
</ul>
<section id="logger-objects">
<h2>Logger Objects<a class="headerlink" href="#logger-objects" title="Link to this heading">¶</a></h2>
Loggers have the following attributes and methods. Note that Loggers should
NEVER be instantiated directly, but always through the module-level function
<code class="docutils literal notranslate">logging.getLogger(name)</code>. Multiple calls to <a class="reference internal" href="#logging.getLogger" title="logging.getLogger"><code class="xref py py-func docutils literal notranslate">getLogger()</code></a> with the same
name will always return a reference to the same Logger object.
The <code class="docutils literal notranslate">name</code> is potentially a period-separated hierarchical value, like
<code class="docutils literal notranslate">foo.bar.baz</code> (though it could also be just plain <code class="docutils literal notranslate">foo</code>, for example).
Loggers that are further down in the hierarchical list are children of loggers
higher up in the list. For example, given a logger with a name of <code class="docutils literal notranslate">foo</code>,
loggers with names of <code class="docutils literal notranslate">foo.bar</code>, <code class="docutils literal notranslate">foo.bar.baz</code>, and <code class="docutils literal notranslate">foo.bam</code> are all
descendants of <code class="docutils literal notranslate">foo</code>. 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
<code class="docutils literal notranslate">logging.getLogger(__name__)</code>. That’s because in a module, <code class="docutils literal notranslate">__name__</code>
is the module’s name in the Python package namespace.
<dl class="py class">
<dt class="sig sig-object py" id="logging.Logger">
class logging.Logger<a class="headerlink" href="#logging.Logger" title="Link to this definition">¶</a></dt>
<dd><dl class="py attribute">
<dt class="sig sig-object py" id="logging.Logger.name">
name<a class="headerlink" href="#logging.Logger.name" title="Link to this definition">¶</a></dt>
<dd>This is the logger’s name, and is the value that was passed to <a class="reference internal" href="#logging.getLogger" title="logging.getLogger"><code class="xref py py-func docutils literal notranslate">getLogger()</code></a>
to obtain the logger.
<div class="admonition note">
Note
This attribute should be treated as read-only.
</div>
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="logging.Logger.level">
level<a class="headerlink" href="#logging.Logger.level" title="Link to this definition">¶</a></dt>
<dd>The threshold of this logger, as set by the <a class="reference internal" href="#logging.Logger.setLevel" title="logging.Logger.setLevel"><code class="xref py py-meth docutils literal notranslate">setLevel()</code></a> method.
<div class="admonition note">
Note
Do not set this attribute directly - always use <a class="reference internal" href="#logging.Logger.setLevel" title="logging.Logger.setLevel"><code class="xref py py-meth docutils literal notranslate">setLevel()</code></a>,
which has checks for the level passed to it.
</div>
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="logging.Logger.parent">
parent<a class="headerlink" href="#logging.Logger.parent" title="Link to this definition">¶</a></dt>
<dd>The parent logger of this logger. It may change based on later instantiation
of loggers which are higher up in the namespace hierarchy.
<div class="admonition note">
Note
This value should be treated as read-only.
</div>
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="logging.Logger.propagate">
propagate<a class="headerlink" href="#logging.Logger.propagate" title="Link to this definition">¶</a></dt>
<dd>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. Messages are passed directly to the
ancestor loggers’ handlers - neither the level nor filters of the ancestor
loggers in question are considered.
If this evaluates to false, logging messages are not passed to the handlers
of ancestor loggers.
Spelling it out with an example: If the propagate attribute of the logger named
<code class="docutils literal notranslate">A.B.C</code> evaluates to true, any event logged to <code class="docutils literal notranslate">A.B.C</code> via a method call such as
<code class="docutils literal notranslate">logging.getLogger('A.B.C').error(...)</code> will [subject to passing that logger’s
level and filter settings] be passed in turn to any handlers attached to loggers
named <code class="docutils literal notranslate">A.B</code>, <code class="docutils literal notranslate">A</code> and the root logger, after first being passed to any handlers
attached to <code class="docutils literal notranslate">A.B.C</code>. If any logger in the chain <code class="docutils literal notranslate">A.B.C</code>, <code class="docutils literal notranslate">A.B</code>, <code class="docutils literal notranslate">A</code> has its
<code class="docutils literal notranslate">propagate</code> attribute set to false, then that is the last logger whose handlers
are offered the event to handle, and propagation stops at that point.
The constructor sets this attribute to <code class="docutils literal notranslate">True</code>.
<div class="admonition note">
Note
If you attach a handler to a logger and one or more of its
ancestors, it may emit the same record multiple times. 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 <code class="docutils literal notranslate">True</code>. A common
scenario is to attach handlers only to the root logger, and to let
propagation take care of the rest.
</div>
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="logging.Logger.handlers">
handlers<a class="headerlink" href="#logging.Logger.handlers" title="Link to this definition">¶</a></dt>
<dd>The list of handlers directly attached to this logger instance.
<div class="admonition note">
Note
This attribute should be treated as read-only; it is normally changed via
the <a class="reference internal" href="#logging.Logger.addHandler" title="logging.Logger.addHandler"><code class="xref py py-meth docutils literal notranslate">addHandler()</code></a> and <a class="reference internal" href="#logging.Logger.removeHandler" title="logging.Logger.removeHandler"><code class="xref py py-meth docutils literal notranslate">removeHandler()</code></a> methods, which use locks to ensure
thread-safe operation.
</div>
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="logging.Logger.disabled">
disabled<a class="headerlink" href="#logging.Logger.disabled" title="Link to this definition">¶</a></dt>
<dd>This attribute disables handling of any events. It is set to <code class="docutils literal notranslate">False</code> in the
initializer, and only changed by logging configuration code.
<div class="admonition note">
Note
This attribute should be treated as read-only.
</div>
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.setLevel">
setLevel(level)<a class="headerlink" href="#logging.Logger.setLevel" title="Link to this definition">¶</a></dt>
<dd>Sets the threshold for this logger to 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.
When a logger is created, the level is set to <a class="reference internal" href="#logging.NOTSET" title="logging.NOTSET"><code class="xref py py-const docutils literal notranslate">NOTSET</code></a> (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). Note that the root logger
is created with level <a class="reference internal" href="#logging.WARNING" title="logging.WARNING"><code class="xref py py-const docutils literal notranslate">WARNING</code></a>.
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.
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.
If the root is reached, and it has a level of NOTSET, then all messages will be
processed. Otherwise, the root’s level will be used as the effective level.
See <a class="reference internal" href="#levels">Logging Levels</a> for a list of levels.
<div class="versionchanged">
Changed in version 3.2: The level parameter now accepts a string representation of the
level such as ‘INFO’ as an alternative to the integer constants
such as <a class="reference internal" href="#logging.INFO" title="logging.INFO"><code class="xref py py-const docutils literal notranslate">INFO</code></a>. Note, however, that levels are internally stored
as integers, and methods such as e.g. <a class="reference internal" href="#logging.Logger.getEffectiveLevel" title="logging.Logger.getEffectiveLevel"><code class="xref py py-meth docutils literal notranslate">getEffectiveLevel()</code></a> and
<a class="reference internal" href="#logging.Logger.isEnabledFor" title="logging.Logger.isEnabledFor"><code class="xref py py-meth docutils literal notranslate">isEnabledFor()</code></a> will return/expect to be passed integers.
</div>
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.isEnabledFor">
isEnabledFor(level)<a class="headerlink" href="#logging.Logger.isEnabledFor" title="Link to this definition">¶</a></dt>
<dd>Indicates if a message of severity level would be processed by this logger.
This method checks first the module-level level set by
<code class="docutils literal notranslate">logging.disable(level)</code> and then the logger’s effective level as determined
by <a class="reference internal" href="#logging.Logger.getEffectiveLevel" title="logging.Logger.getEffectiveLevel"><code class="xref py py-meth docutils literal notranslate">getEffectiveLevel()</code></a>.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.getEffectiveLevel">
getEffectiveLevel()<a class="headerlink" href="#logging.Logger.getEffectiveLevel" title="Link to this definition">¶</a></dt>
<dd>Indicates the effective level for this logger. If a value other than
<a class="reference internal" href="#logging.NOTSET" title="logging.NOTSET"><code class="xref py py-const docutils literal notranslate">NOTSET</code></a> has been set using <a class="reference internal" href="#logging.Logger.setLevel" title="logging.Logger.setLevel"><code class="xref py py-meth docutils literal notranslate">setLevel()</code></a>, it is returned. Otherwise,
the hierarchy is traversed towards the root until a value other than
<a class="reference internal" href="#logging.NOTSET" title="logging.NOTSET"><code class="xref py py-const docutils literal notranslate">NOTSET</code></a> is found, and that value is returned. The value returned is
an integer, typically one of <a class="reference internal" href="#logging.DEBUG" title="logging.DEBUG"><code class="xref py py-const docutils literal notranslate">logging.DEBUG</code></a>, <a class="reference internal" href="#logging.INFO" title="logging.INFO"><code class="xref py py-const docutils literal notranslate">logging.INFO</code></a>
etc.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.getChild">
getChild(suffix)<a class="headerlink" href="#logging.Logger.getChild" title="Link to this definition">¶</a></dt>
<dd>Returns a logger which is a descendant to this logger, as determined by the suffix.
Thus, <code class="docutils literal notranslate">logging.getLogger('abc').getChild('def.ghi')</code> would return the same
logger as would be returned by <code class="docutils literal notranslate">logging.getLogger('abc.def.ghi')</code>. This is a
convenience method, useful when the parent logger is named using e.g. <code class="docutils literal notranslate">__name__</code>
rather than a literal string.
<div class="versionadded">
New in version 3.2.
</div>
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.getChildren">
getChildren()<a class="headerlink" href="#logging.Logger.getChildren" title="Link to this definition">¶</a></dt>
<dd>Returns a set of loggers which are immediate children of this logger. So for
example <code class="docutils literal notranslate">logging.getLogger().getChildren()</code> might return a set containing
loggers named <code class="docutils literal notranslate">foo</code> and <code class="docutils literal notranslate">bar</code>, but a logger named <code class="docutils literal notranslate">foo.bar</code> wouldn’t be
included in the set. Likewise, <code class="docutils literal notranslate">logging.getLogger('foo').getChildren()</code> might
return a set including a logger named <code class="docutils literal notranslate">foo.bar</code>, but it wouldn’t include one
named <code class="docutils literal notranslate">foo.bar.baz</code>.
<div class="versionadded">
New in version 3.12.
</div>
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.debug">
debug(msg, *args, **kwargs)<a class="headerlink" href="#logging.Logger.debug" title="Link to this definition">¶</a></dt>
<dd>Logs a message with level <a class="reference internal" href="#logging.DEBUG" title="logging.DEBUG"><code class="xref py py-const docutils literal notranslate">DEBUG</code></a> on this logger. The msg is the
message format string, and the args are the arguments which are merged into
msg using the string formatting operator. (Note that this means that you can
use keywords in the format string, together with a single dictionary argument.)
No % formatting operation is performed on msg when no args are supplied.
There are four keyword arguments in kwargs which are inspected:
exc_info, stack_info, stacklevel and extra.
If exc_info does not evaluate as false, it causes exception information to be
added to the logging message. If an exception tuple (in the format returned by
<a class="reference internal" href="sys.html#sys.exc_info" title="sys.exc_info"><code class="xref py py-func docutils literal notranslate">sys.exc_info()</code></a>) or an exception instance is provided, it is used;
otherwise, <a class="reference internal" href="sys.html#sys.exc_info" title="sys.exc_info"><code class="xref py py-func docutils literal notranslate">sys.exc_info()</code></a> is called to get the exception information.
The second optional keyword argument is stack_info, which defaults to
<code class="docutils literal notranslate">False</code>. 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:
<div class="highlight-none notranslate"><div class="highlight"><pre>Stack (most recent call last):
</pre></div>
</div>
This mimics the <code class="docutils literal notranslate">Traceback (most recent call last):</code> which is used when
displaying exception frames.
The third optional keyword argument is stacklevel, which defaults to <code class="docutils literal notranslate">1</code>.
If greater than 1, the corresponding number of stack frames are skipped
when computing the line number and function name set in the <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a>
created for the logging event. 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. The name of this
parameter mirrors the equivalent one in the <a class="reference internal" href="warnings.html#module-warnings" title="warnings: Issue warning messages and control their disposition."><code class="xref py py-mod docutils literal notranslate">warnings</code></a> module.
The fourth keyword argument is extra which can be used to pass a
dictionary which is used to populate the __dict__ of the <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a>
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:
<div class="highlight-python3 notranslate"><div class="highlight"><pre>FORMAT = &#39;%(asctime)s %(clientip)-15s %(user)-8s %(message)s&#39;
logging.basicConfig(format=FORMAT)
d = {&#39;clientip&#39;: &#39;192.168.0.1&#39;, &#39;user&#39;: &#39;fbloggs&#39;}
logger = logging.getLogger(&#39;tcpserver&#39;)
logger.warning(&#39;Protocol problem: %s&#39;, &#39;connection reset&#39;, extra=d)
</pre></div>
</div>
would print something like
<div class="highlight-none notranslate"><div class="highlight"><pre>2006-02-08 22:20:02,165 192.168.0.1 fbloggs Protocol problem: connection reset
</pre></div>
</div>
The keys in the dictionary passed in extra should not clash with the keys used
by the logging system. (See the section on <a class="reference internal" href="#logrecord-attributes">LogRecord attributes</a> 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 <a class="reference internal" href="#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate">Formatter</code></a> has been
set up with a format string which expects ‘clientip’ and ‘user’ in the attribute
dictionary of the <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a>. 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
<a class="reference internal" href="#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate">Formatter</code></a>s would be used with particular <a class="reference internal" href="#logging.Handler" title="logging.Handler"><code class="xref py py-class docutils literal notranslate">Handler</code></a>s.
If no handler is attached to this logger (or any of its ancestors,
taking into account the relevant <a class="reference internal" href="#logging.Logger.propagate" title="logging.Logger.propagate"><code class="xref py py-attr docutils literal notranslate">Logger.propagate</code></a> attributes),
the message will be sent to the handler set on <a class="reference internal" href="#logging.lastResort" title="logging.lastResort"><code class="xref py py-attr docutils literal notranslate">lastResort</code></a>.
<div class="versionchanged">
Changed in version 3.2: The stack_info parameter was added.
</div>
<div class="versionchanged">
Changed in version 3.5: The exc_info parameter can now accept exception instances.
</div>
<div class="versionchanged">
Changed in version 3.8: The stacklevel parameter was added.
</div>
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.info">
info(msg, *args, **kwargs)<a class="headerlink" href="#logging.Logger.info" title="Link to this definition">¶</a></dt>
<dd>Logs a message with level <a class="reference internal" href="#logging.INFO" title="logging.INFO"><code class="xref py py-const docutils literal notranslate">INFO</code></a> on this logger. The arguments are
interpreted as for <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-meth docutils literal notranslate">debug()</code></a>.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.warning">
warning(msg, *args, **kwargs)<a class="headerlink" href="#logging.Logger.warning" title="Link to this definition">¶</a></dt>
<dd>Logs a message with level <a class="reference internal" href="#logging.WARNING" title="logging.WARNING"><code class="xref py py-const docutils literal notranslate">WARNING</code></a> on this logger. The arguments are
interpreted as for <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-meth docutils literal notranslate">debug()</code></a>.
<div class="admonition note">
Note
There is an obsolete method <code class="docutils literal notranslate">warn</code> which is functionally
identical to <code class="docutils literal notranslate">warning</code>. As <code class="docutils literal notranslate">warn</code> is deprecated, please do not use
it - use <code class="docutils literal notranslate">warning</code> instead.
</div>
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.error">
error(msg, *args, **kwargs)<a class="headerlink" href="#logging.Logger.error" title="Link to this definition">¶</a></dt>
<dd>Logs a message with level <a class="reference internal" href="#logging.ERROR" title="logging.ERROR"><code class="xref py py-const docutils literal notranslate">ERROR</code></a> on this logger. The arguments are
interpreted as for <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-meth docutils literal notranslate">debug()</code></a>.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.critical">
critical(msg, *args, **kwargs)<a class="headerlink" href="#logging.Logger.critical" title="Link to this definition">¶</a></dt>
<dd>Logs a message with level <a class="reference internal" href="#logging.CRITICAL" title="logging.CRITICAL"><code class="xref py py-const docutils literal notranslate">CRITICAL</code></a> on this logger. The arguments are
interpreted as for <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-meth docutils literal notranslate">debug()</code></a>.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.log">
log(level, msg, *args, **kwargs)<a class="headerlink" href="#logging.Logger.log" title="Link to this definition">¶</a></dt>
<dd>Logs a message with integer level level on this logger. The other arguments are
interpreted as for <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-meth docutils literal notranslate">debug()</code></a>.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.exception">
exception(msg, *args, **kwargs)<a class="headerlink" href="#logging.Logger.exception" title="Link to this definition">¶</a></dt>
<dd>Logs a message with level <a class="reference internal" href="#logging.ERROR" title="logging.ERROR"><code class="xref py py-const docutils literal notranslate">ERROR</code></a> on this logger. The arguments are
interpreted as for <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-meth docutils literal notranslate">debug()</code></a>. Exception info is added to the logging
message. This method should only be called from an exception handler.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.addFilter">
addFilter(filter)<a class="headerlink" href="#logging.Logger.addFilter" title="Link to this definition">¶</a></dt>
<dd>Adds the specified filter filter to this logger.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.removeFilter">
removeFilter(filter)<a class="headerlink" href="#logging.Logger.removeFilter" title="Link to this definition">¶</a></dt>
<dd>Removes the specified filter filter from this logger.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.filter">
filter(record)<a class="headerlink" href="#logging.Logger.filter" title="Link to this definition">¶</a></dt>
<dd>Apply this logger’s filters to the record and return <code class="docutils literal notranslate">True</code> if the
record is to be processed. The filters are consulted in turn, until one of
them returns a false value. If none of them return a false value, the record
will be processed (passed to handlers). If one returns a false value, no
further processing of the record occurs.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.addHandler">
addHandler(hdlr)<a class="headerlink" href="#logging.Logger.addHandler" title="Link to this definition">¶</a></dt>
<dd>Adds the specified handler hdlr to this logger.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.removeHandler">
removeHandler(hdlr)<a class="headerlink" href="#logging.Logger.removeHandler" title="Link to this definition">¶</a></dt>
<dd>Removes the specified handler hdlr from this logger.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.findCaller">
findCaller(stack_info=False, stacklevel=1)<a class="headerlink" href="#logging.Logger.findCaller" title="Link to this definition">¶</a></dt>
<dd>Finds the caller’s source filename and line number. Returns the filename, line
number, function name and stack information as a 4-element tuple. The stack
information is returned as <code class="docutils literal notranslate">None</code> unless stack_info is <code class="docutils literal notranslate">True</code>.
The stacklevel parameter is passed from code calling the <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-meth docutils literal notranslate">debug()</code></a>
and other APIs. If greater than 1, the excess is used to skip stack frames
before determining the values to be returned. 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.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.handle">
handle(record)<a class="headerlink" href="#logging.Logger.handle" title="Link to this definition">¶</a></dt>
<dd>Handles a record by passing it to all handlers associated with this logger and
its ancestors (until a false value of propagate is found). This method is used
for unpickled records received from a socket, as well as those created locally.
Logger-level filtering is applied using <a class="reference internal" href="#logging.Logger.filter" title="logging.Logger.filter"><code class="xref py py-meth docutils literal notranslate">filter()</code></a>.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.makeRecord">
makeRecord(name, level, fn, lno, msg, args, exc_info, func=None, extra=None, sinfo=None)<a class="headerlink" href="#logging.Logger.makeRecord" title="Link to this definition">¶</a></dt>
<dd>This is a factory method which can be overridden in subclasses to create
specialized <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> instances.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Logger.hasHandlers">
hasHandlers()<a class="headerlink" href="#logging.Logger.hasHandlers" title="Link to this definition">¶</a></dt>
<dd>Checks to see if this logger has any handlers configured. This is done by
looking for handlers in this logger and its parents in the logger hierarchy.
Returns <code class="docutils literal notranslate">True</code> if a handler was found, else <code class="docutils literal notranslate">False</code>. 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.
<div class="versionadded">
New in version 3.2.
</div>
</dd></dl>

<div class="versionchanged">
Changed in version 3.7: Loggers can now be pickled and unpickled.
</div>
</dd></dl>

</section>
<section id="logging-levels">
<h2>Logging Levels<a class="headerlink" href="#logging-levels" title="Link to this heading">¶</a></h2>
The numeric values of logging levels are given in the following table. 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. If you define a level
with the same numeric value, it overwrites the predefined value; the predefined
name is lost.
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head">Level</th>
<th class="head">Numeric value</th>
<th class="head">What it means / When to use it</th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><dl class="py data">
<dt class="sig sig-object py" id="logging.NOTSET">
logging.NOTSET<a class="headerlink" href="#logging.NOTSET" title="Link to this definition">¶</a></dt>
<dd></dd></dl>

</td>
<td>0</td>
<td>When set on a logger, indicates that
ancestor loggers are to be consulted
to determine the effective level.
If that still resolves to
<code class="xref py py-const docutils literal notranslate">NOTSET</code>, then all events
are logged. When set on a handler,
all events are handled.</td>
</tr>
<tr class="row-odd"><td><dl class="py data">
<dt class="sig sig-object py" id="logging.DEBUG">
logging.DEBUG<a class="headerlink" href="#logging.DEBUG" title="Link to this definition">¶</a></dt>
<dd></dd></dl>

</td>
<td>10</td>
<td>Detailed information, typically only
of interest to a developer trying to
diagnose a problem.</td>
</tr>
<tr class="row-even"><td><dl class="py data">
<dt class="sig sig-object py" id="logging.INFO">
logging.INFO<a class="headerlink" href="#logging.INFO" title="Link to this definition">¶</a></dt>
<dd></dd></dl>

</td>
<td>20</td>
<td>Confirmation that things are working
as expected.</td>
</tr>
<tr class="row-odd"><td><dl class="py data">
<dt class="sig sig-object py" id="logging.WARNING">
logging.WARNING<a class="headerlink" href="#logging.WARNING" title="Link to this definition">¶</a></dt>
<dd></dd></dl>

</td>
<td>30</td>
<td>An indication that something
unexpected happened, or that a
problem might occur in the near
future (e.g. ‘disk space low’). The
software is still working as
expected.</td>
</tr>
<tr class="row-even"><td><dl class="py data">
<dt class="sig sig-object py" id="logging.ERROR">
logging.ERROR<a class="headerlink" href="#logging.ERROR" title="Link to this definition">¶</a></dt>
<dd></dd></dl>

</td>
<td>40</td>
<td>Due to a more serious problem, the
software has not been able to
perform some function.</td>
</tr>
<tr class="row-odd"><td><dl class="py data">
<dt class="sig sig-object py" id="logging.CRITICAL">
logging.CRITICAL<a class="headerlink" href="#logging.CRITICAL" title="Link to this definition">¶</a></dt>
<dd></dd></dl>

</td>
<td>50</td>
<td>A serious error, indicating that the
program itself may be unable to
continue running.</td>
</tr>
</tbody>
</table>
</section>
<section id="handler-objects">
<h2>Handler Objects<a class="headerlink" href="#handler-objects" title="Link to this heading">¶</a></h2>
Handlers have the following attributes and methods. Note that <a class="reference internal" href="#logging.Handler" title="logging.Handler"><code class="xref py py-class docutils literal notranslate">Handler</code></a>
is never instantiated directly; this class acts as a base for more useful
subclasses. However, the <code class="xref py py-meth docutils literal notranslate">__init__()</code> method in subclasses needs to call
<a class="reference internal" href="#logging.Handler.__init__" title="logging.Handler.__init__"><code class="xref py py-meth docutils literal notranslate">Handler.__init__()</code></a>.
<dl class="py class">
<dt class="sig sig-object py" id="logging.Handler">
class logging.Handler<a class="headerlink" href="#logging.Handler" title="Link to this definition">¶</a></dt>
<dd><dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.__init__">
__init__(level=NOTSET)<a class="headerlink" href="#logging.Handler.__init__" title="Link to this definition">¶</a></dt>
<dd>Initializes the <a class="reference internal" href="#logging.Handler" title="logging.Handler"><code class="xref py py-class docutils literal notranslate">Handler</code></a> instance by setting its level, setting the list
of filters to the empty list and creating a lock (using <a class="reference internal" href="#logging.Handler.createLock" title="logging.Handler.createLock"><code class="xref py py-meth docutils literal notranslate">createLock()</code></a>) for
serializing access to an I/O mechanism.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.createLock">
createLock()<a class="headerlink" href="#logging.Handler.createLock" title="Link to this definition">¶</a></dt>
<dd>Initializes a thread lock which can be used to serialize access to underlying
I/O functionality which may not be threadsafe.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.acquire">
acquire()<a class="headerlink" href="#logging.Handler.acquire" title="Link to this definition">¶</a></dt>
<dd>Acquires the thread lock created with <a class="reference internal" href="#logging.Handler.createLock" title="logging.Handler.createLock"><code class="xref py py-meth docutils literal notranslate">createLock()</code></a>.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.release">
release()<a class="headerlink" href="#logging.Handler.release" title="Link to this definition">¶</a></dt>
<dd>Releases the thread lock acquired with <a class="reference internal" href="#logging.Handler.acquire" title="logging.Handler.acquire"><code class="xref py py-meth docutils literal notranslate">acquire()</code></a>.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.setLevel">
setLevel(level)<a class="headerlink" href="#logging.Handler.setLevel" title="Link to this definition">¶</a></dt>
<dd>Sets the threshold for this handler to level. Logging messages which are
less severe than level will be ignored. When a handler is created, the
level is set to <a class="reference internal" href="#logging.NOTSET" title="logging.NOTSET"><code class="xref py py-const docutils literal notranslate">NOTSET</code></a> (which causes all messages to be
processed).
See <a class="reference internal" href="#levels">Logging Levels</a> for a list of levels.
<div class="versionchanged">
Changed in version 3.2: The level parameter now accepts a string representation of the
level such as ‘INFO’ as an alternative to the integer constants
such as <a class="reference internal" href="#logging.INFO" title="logging.INFO"><code class="xref py py-const docutils literal notranslate">INFO</code></a>.
</div>
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.setFormatter">
setFormatter(fmt)<a class="headerlink" href="#logging.Handler.setFormatter" title="Link to this definition">¶</a></dt>
<dd>Sets the <a class="reference internal" href="#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate">Formatter</code></a> for this handler to fmt.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.addFilter">
addFilter(filter)<a class="headerlink" href="#logging.Handler.addFilter" title="Link to this definition">¶</a></dt>
<dd>Adds the specified filter filter to this handler.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.removeFilter">
removeFilter(filter)<a class="headerlink" href="#logging.Handler.removeFilter" title="Link to this definition">¶</a></dt>
<dd>Removes the specified filter filter from this handler.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.filter">
filter(record)<a class="headerlink" href="#logging.Handler.filter" title="Link to this definition">¶</a></dt>
<dd>Apply this handler’s filters to the record and return <code class="docutils literal notranslate">True</code> if the
record is to be processed. The filters are consulted in turn, until one of
them returns a false value. If none of them return a false value, the record
will be emitted. If one returns a false value, the handler will not emit the
record.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.flush">
flush()<a class="headerlink" href="#logging.Handler.flush" title="Link to this definition">¶</a></dt>
<dd>Ensure all logging output has been flushed. This version does nothing and is
intended to be implemented by subclasses.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.close">
close()<a class="headerlink" href="#logging.Handler.close" title="Link to this definition">¶</a></dt>
<dd>Tidy up any resources used by the handler. This version does no output but
removes the handler from an internal list of handlers which is closed when
<a class="reference internal" href="#logging.shutdown" title="logging.shutdown"><code class="xref py py-func docutils literal notranslate">shutdown()</code></a> is called. Subclasses should ensure that this gets called
from overridden <a class="reference internal" href="#logging.Handler.close" title="logging.Handler.close"><code class="xref py py-meth docutils literal notranslate">close()</code></a> methods.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.handle">
handle(record)<a class="headerlink" href="#logging.Handler.handle" title="Link to this definition">¶</a></dt>
<dd>Conditionally emits the specified logging record, depending on filters which may
have been added to the handler. Wraps the actual emission of the record with
acquisition/release of the I/O thread lock.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.handleError">
handleError(record)<a class="headerlink" href="#logging.Handler.handleError" title="Link to this definition">¶</a></dt>
<dd>This method should be called from handlers when an exception is encountered
during an <a class="reference internal" href="#logging.Handler.emit" title="logging.Handler.emit"><code class="xref py py-meth docutils literal notranslate">emit()</code></a> call. If the module-level attribute
<a class="reference internal" href="#logging.raiseExceptions" title="logging.raiseExceptions"><code class="xref py py-data docutils literal notranslate">raiseExceptions</code></a> is <code class="docutils literal notranslate">False</code>, 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. (The default value of <a class="reference internal" href="#logging.raiseExceptions" title="logging.raiseExceptions"><code class="xref py py-data docutils literal notranslate">raiseExceptions</code></a> is <code class="docutils literal notranslate">True</code>, as that is
more useful during development).
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.format">
format(record)<a class="headerlink" href="#logging.Handler.format" title="Link to this definition">¶</a></dt>
<dd>Do formatting for a record - if a formatter is set, use it. Otherwise, use the
default formatter for the module.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Handler.emit">
emit(record)<a class="headerlink" href="#logging.Handler.emit" title="Link to this definition">¶</a></dt>
<dd>Do whatever it takes to actually log the specified logging record. This version
is intended to be implemented by subclasses and so raises a
<a class="reference internal" href="exceptions.html#NotImplementedError" title="NotImplementedError"><code class="xref py py-exc docutils literal notranslate">NotImplementedError</code></a>.
<div class="admonition warning">
Warning
This method is called after a handler-level lock is acquired, which
is released after this method returns. When you override this method, note
that you should be careful when calling anything that invokes other parts of
the logging API which might do locking, because that might result in a
deadlock. Specifically:
<ul class="simple">
<li>Logging configuration APIs acquire the module-level lock, and then
individual handler-level locks as those handlers are configured.</li>
<li>Many logging APIs lock the module-level lock. If such an API is called
from this method, it could cause a deadlock if a configuration call is
made on another thread, because that thread will try to acquire the
module-level lock before the handler-level lock, whereas this thread
tries to acquire the module-level lock after the handler-level lock
(because in this method, the handler-level lock has already been acquired).</li>
</ul>
</div>
</dd></dl>

</dd></dl>

For a list of handlers included as standard, see <a class="reference internal" href="logging.handlers.html#module-logging.handlers" title="logging.handlers: Handlers for the logging module."><code class="xref py py-mod docutils literal notranslate">logging.handlers</code></a>.
</section>
<section id="formatter-objects">
<h2>Formatter Objects<a class="headerlink" href="#formatter-objects" title="Link to this heading">¶</a></h2>
<dl class="py class">
<dt class="sig sig-object py" id="logging.Formatter">
class logging.Formatter(fmt=None, datefmt=None, style='%', validate=True, *, defaults=None)<a class="headerlink" href="#logging.Formatter" title="Link to this definition">¶</a></dt>
<dd>Responsible for converting a <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> to an output string
to be interpreted by a human or external system.
<dl class="field-list simple">
<dt class="field-odd">Parameters:</dt>
<dd class="field-odd"><ul class="simple">
<li>fmt (<a class="reference internal" href="stdtypes.html#str" title="str">str</a>) – A format string in the given style for
the logged output as a whole.
The possible mapping keys are drawn from the <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> object’s
<a class="reference internal" href="#logrecord-attributes">LogRecord attributes</a>.
If not specified, <code class="docutils literal notranslate">'%(message)s'</code> is used,
which is just the logged message.</li>
<li>datefmt (<a class="reference internal" href="stdtypes.html#str" title="str">str</a>) – A format string in the given style for
the date/time portion of the logged output.
If not specified, the default described in <a class="reference internal" href="#logging.Formatter.formatTime" title="logging.Formatter.formatTime"><code class="xref py py-meth docutils literal notranslate">formatTime()</code></a> is used.</li>
<li>style (<a class="reference internal" href="stdtypes.html#str" title="str">str</a>) – Can be one of <code class="docutils literal notranslate">'%'</code>, <code class="docutils literal notranslate">'{'</code> or <code class="docutils literal notranslate">'$'</code> and determines
how the format string will be merged with its data: using one of
<a class="reference internal" href="stdtypes.html#old-string-formatting">printf-style String Formatting</a> (<code class="docutils literal notranslate">%</code>), <a class="reference internal" href="stdtypes.html#str.format" title="str.format"><code class="xref py py-meth docutils literal notranslate">str.format()</code></a> (<code class="docutils literal notranslate">{</code>)
or <a class="reference internal" href="string.html#string.Template" title="string.Template"><code class="xref py py-class docutils literal notranslate">string.Template</code></a> (<code class="docutils literal notranslate">$</code>). This only applies to
fmt and datefmt (e.g. <code class="docutils literal notranslate">'%(message)s'</code> versus <code class="docutils literal notranslate">'{message}'</code>),
not to the actual log messages passed to the logging methods.
However, there are <a class="reference internal" href="../howto/logging-cookbook.html#formatting-styles">other ways</a>
to use <code class="docutils literal notranslate">{</code>- and <code class="docutils literal notranslate">$</code>-formatting for log messages.</li>
<li>validate (<a class="reference internal" href="functions.html#bool" title="bool">bool</a>) – If <code class="docutils literal notranslate">True</code> (the default), incorrect or mismatched
fmt and style will raise a <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate">ValueError</code></a>; for example,
<code class="docutils literal notranslate">logging.Formatter('%(asctime)s - %(message)s', style='{')</code>.</li>
<li>defaults (<a class="reference internal" href="stdtypes.html#dict" title="dict">dict</a>[<a class="reference internal" href="stdtypes.html#str" title="str">str</a>, Any]) – A dictionary with default values to use in custom fields.
For example,
<code class="docutils literal notranslate">logging.Formatter('%(ip)s %(message)s', defaults={&quot;ip&quot;: None})</code></li>
</ul>
</dd>
</dl>
<div class="versionchanged">
Changed in version 3.2: Added the style parameter.
</div>
<div class="versionchanged">
Changed in version 3.8: Added the validate parameter.
</div>
<div class="versionchanged">
Changed in version 3.10: Added the defaults parameter.
</div>
<dl class="py method">
<dt class="sig sig-object py" id="logging.Formatter.format">
format(record)<a class="headerlink" href="#logging.Formatter.format" title="Link to this definition">¶</a></dt>
<dd>The record’s attribute dictionary is used as the operand to a string
formatting operation. Returns the resulting string. Before formatting the
dictionary, a couple of preparatory steps are carried out. The message
attribute of the record is computed using msg % args. If the
formatting string contains <code class="docutils literal notranslate">'(asctime)'</code>, <a class="reference internal" href="#logging.Formatter.formatTime" title="logging.Formatter.formatTime"><code class="xref py py-meth docutils literal notranslate">formatTime()</code></a> is called
to format the event time. If there is exception information, it is
formatted using <a class="reference internal" href="#logging.Formatter.formatException" title="logging.Formatter.formatException"><code class="xref py py-meth docutils literal notranslate">formatException()</code></a> 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 <a class="reference internal" href="#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate">Formatter</code></a> 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 <code class="docutils literal notranslate">None</code>) 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 <a class="reference internal" href="#logging.Formatter.formatStack" title="logging.Formatter.formatStack"><code class="xref py py-meth docutils literal notranslate">formatStack()</code></a> to transform it if necessary.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Formatter.formatTime">
formatTime(record, datefmt=None)<a class="headerlink" href="#logging.Formatter.formatTime" title="Link to this definition">¶</a></dt>
<dd>This method should be called from <a class="reference internal" href="functions.html#format" title="format"><code class="xref py py-meth docutils literal notranslate">format()</code></a> 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
<a class="reference internal" href="time.html#time.strftime" title="time.strftime"><code class="xref py py-func docutils literal notranslate">time.strftime()</code></a> 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
<a class="reference internal" href="time.html#time.strftime" title="time.strftime"><code class="xref py py-func docutils literal notranslate">time.strftime()</code></a> documentation. An example time in this format is
<code class="docutils literal notranslate">2003-01-23 00:29:50,411</code>. The resulting string is returned.
This function uses a user-configurable function to convert the creation
time to a tuple. By default, <a class="reference internal" href="time.html#time.localtime" title="time.localtime"><code class="xref py py-func docutils literal notranslate">time.localtime()</code></a> is used; to change
this for a particular formatter instance, set the <code class="docutils literal notranslate">converter</code> attribute
to a function with the same signature as <a class="reference internal" href="time.html#time.localtime" title="time.localtime"><code class="xref py py-func docutils literal notranslate">time.localtime()</code></a> or
<a class="reference internal" href="time.html#time.gmtime" title="time.gmtime"><code class="xref py py-func docutils literal notranslate">time.gmtime()</code></a>. To change it for all formatters, for example if you
want all logging times to be shown in GMT, set the <code class="docutils literal notranslate">converter</code>
attribute in the <code class="docutils literal notranslate">Formatter</code> class.
<div class="versionchanged">
Changed in version 3.3: Previously, the default format was hard-coded as in this example:
<code class="docutils literal notranslate">2010-09-06 22:38:15,292</code> where the part before the comma is
handled by a strptime format string (<code class="docutils literal notranslate">'%Y-%m-%d %H:%M:%S'</code>), 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, <code class="docutils literal notranslate">'%s,%03d'</code> — 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 <code class="docutils literal notranslate">default_time_format</code> (for the strptime format string)
and <code class="docutils literal notranslate">default_msec_format</code> (for appending the millisecond value).
</div>
<div class="versionchanged">
Changed in version 3.9: The <code class="docutils literal notranslate">default_msec_format</code> can be <code class="docutils literal notranslate">None</code>.
</div>
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Formatter.formatException">
formatException(exc_info)<a class="headerlink" href="#logging.Formatter.formatException" title="Link to this definition">¶</a></dt>
<dd>Formats the specified exception information (a standard exception tuple as
returned by <a class="reference internal" href="sys.html#sys.exc_info" title="sys.exc_info"><code class="xref py py-func docutils literal notranslate">sys.exc_info()</code></a>) as a string. This default implementation
just uses <a class="reference internal" href="traceback.html#traceback.print_exception" title="traceback.print_exception"><code class="xref py py-func docutils literal notranslate">traceback.print_exception()</code></a>. The resulting string is
returned.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.Formatter.formatStack">
formatStack(stack_info)<a class="headerlink" href="#logging.Formatter.formatStack" title="Link to this definition">¶</a></dt>
<dd>Formats the specified stack information (a string as returned by
<a class="reference internal" href="traceback.html#traceback.print_stack" title="traceback.print_stack"><code class="xref py py-func docutils literal notranslate">traceback.print_stack()</code></a>, but with the last newline removed) as a
string. This default implementation just returns the input value.
</dd></dl>

</dd></dl>

<dl class="py class">
<dt class="sig sig-object py" id="logging.BufferingFormatter">
class logging.BufferingFormatter(linefmt=None)<a class="headerlink" href="#logging.BufferingFormatter" title="Link to this definition">¶</a></dt>
<dd>A base formatter class suitable for subclassing when you want to format a
number of records. You can pass a <a class="reference internal" href="#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate">Formatter</code></a> instance which you want
to use to format each line (that corresponds to a single record). If not
specified, the default formatter (which just outputs the event message) is
used as the line formatter.
<dl class="py method">
<dt class="sig sig-object py" id="logging.BufferingFormatter.formatHeader">
formatHeader(records)<a class="headerlink" href="#logging.BufferingFormatter.formatHeader" title="Link to this definition">¶</a></dt>
<dd>Return a header for a list of records. The base implementation just
returns the empty string. You will need to override this method if you
want specific behaviour, e.g. to show the count of records, a title or a
separator line.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.BufferingFormatter.formatFooter">
formatFooter(records)<a class="headerlink" href="#logging.BufferingFormatter.formatFooter" title="Link to this definition">¶</a></dt>
<dd>Return a footer for a list of records. The base implementation just
returns the empty string. You will need to override this method if you
want specific behaviour, e.g. to show the count of records or a separator
line.
</dd></dl>

<dl class="py method">
<dt class="sig sig-object py" id="logging.BufferingFormatter.format">
format(records)<a class="headerlink" href="#logging.BufferingFormatter.format" title="Link to this definition">¶</a></dt>
<dd>Return formatted text for a list of records. The base implementation
just returns the empty string if there are no records; otherwise, it
returns the concatenation of the header, each record formatted with the
line formatter, and the footer.
</dd></dl>

</dd></dl>

</section>
<section id="filter-objects">
<h2>Filter Objects<a class="headerlink" href="#filter-objects" title="Link to this heading">¶</a></h2>
<code class="docutils literal notranslate">Filters</code> can be used by <code class="docutils literal notranslate">Handlers</code> and <code class="docutils literal notranslate">Loggers</code> 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.
<dl class="py class">
<dt class="sig sig-object py" id="logging.Filter">
class logging.Filter(name='')<a class="headerlink" href="#logging.Filter" title="Link to this definition">¶</a></dt>
<dd>Returns an instance of the <a class="reference internal" href="#logging.Filter" title="logging.Filter"><code class="xref py py-class docutils literal notranslate">Filter</code></a> 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.
<dl class="py method">
<dt class="sig sig-object py" id="logging.Filter.filter">
filter(record)<a class="headerlink" href="#logging.Filter.filter" title="Link to this definition">¶</a></dt>
<dd>Is the specified record to be logged? Returns false for no, true for
yes. Filters can either modify log records in-place or return a completely
different record instance which will replace the original
log record in any future processing of the event.
</dd></dl>

</dd></dl>

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 <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-meth docutils literal notranslate">debug()</code></a>, <a class="reference internal" href="#logging.info" title="logging.info"><code class="xref py py-meth docutils literal notranslate">info()</code></a>,
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 <code class="docutils literal notranslate">Filter</code>: you can pass any instance
which has a <code class="docutils literal notranslate">filter</code> method with the same semantics.
<div class="versionchanged">
Changed in version 3.2: You don’t need to create specialized <code class="docutils literal notranslate">Filter</code> classes, or use other
classes with a <code class="docutils literal notranslate">filter</code> 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 <code class="docutils literal notranslate">filter</code> attribute: if it does, it’s assumed to be a
<code class="docutils literal notranslate">Filter</code> and its <a class="reference internal" href="#logging.Filter.filter" title="logging.Filter.filter"><code class="xref py py-meth docutils literal notranslate">filter()</code></a> 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
<a class="reference internal" href="#logging.Filter.filter" title="logging.Filter.filter"><code class="xref py py-meth docutils literal notranslate">filter()</code></a>.
</div>
<div class="versionchanged">
Changed in version 3.12: You can now return a <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> instance from filters to replace
the log record rather than modifying it in place. This allows filters attached to
a <a class="reference internal" href="#logging.Handler" title="logging.Handler"><code class="xref py py-class docutils literal notranslate">Handler</code></a> to modify the log record before it is emitted, without
having side effects on other handlers.
</div>
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 <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> 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 <a class="reference internal" href="../howto/logging-cookbook.html#filters-contextual">Using Filters to impart contextual information</a>).
</section>
<section id="logrecord-objects">
<h2>LogRecord Objects<a class="headerlink" href="#logrecord-objects" title="Link to this heading">¶</a></h2>
<a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> instances are created automatically by the <a class="reference internal" href="#logging.Logger" title="logging.Logger"><code class="xref py py-class docutils literal notranslate">Logger</code></a>
every time something is logged, and can be created manually via
<a class="reference internal" href="#logging.makeLogRecord" title="logging.makeLogRecord"><code class="xref py py-func docutils literal notranslate">makeLogRecord()</code></a> (for example, from a pickled event received over the
wire).
<dl class="py class">
<dt class="sig sig-object py" id="logging.LogRecord">
class logging.LogRecord(name, level, pathname, lineno, msg, args, exc_info, func=None, sinfo=None)<a class="headerlink" href="#logging.LogRecord" title="Link to this definition">¶</a></dt>
<dd>Contains all the information pertinent to the event being logged.
The primary information is passed in msg and args,
which are combined using <code class="docutils literal notranslate">msg % args</code> to create
the <code class="xref py py-attr docutils literal notranslate">message</code> attribute of the record.
<dl class="field-list simple">
<dt class="field-odd">Parameters:</dt>
<dd class="field-odd"><ul class="simple">
<li>name (<a class="reference internal" href="stdtypes.html#str" title="str">str</a>) – The name of the logger used to log the event
represented by this <code class="xref py py-class docutils literal notranslate">LogRecord</code>.
Note that the logger name in the <code class="xref py py-class docutils literal notranslate">LogRecord</code>
will always have this value,
even though it may be emitted by a handler
attached to a different (ancestor) logger.</li>
<li>level (<a class="reference internal" href="functions.html#int" title="int">int</a>) – The <a class="reference internal" href="#levels">numeric level</a> of the logging event
(such as <code class="docutils literal notranslate">10</code> for <code class="docutils literal notranslate">DEBUG</code>, <code class="docutils literal notranslate">20</code> for <code class="docutils literal notranslate">INFO</code>, etc).
Note that this is converted to two attributes of the LogRecord:
<code class="xref py py-attr docutils literal notranslate">levelno</code> for the numeric value
and <code class="xref py py-attr docutils literal notranslate">levelname</code> for the corresponding level name.</li>
<li>pathname (<a class="reference internal" href="stdtypes.html#str" title="str">str</a>) – The full string path of the source file
where the logging call was made.</li>
<li>lineno (<a class="reference internal" href="functions.html#int" title="int">int</a>) – The line number in the source file
where the logging call was made.</li>
<li>msg (<a class="reference internal" href="typing.html#typing.Any" title="typing.Any">Any</a>) – The event description message,
which can be a %-format string with placeholders for variable data,
or an arbitrary object (see <a class="reference internal" href="../howto/logging.html#arbitrary-object-messages">Using arbitrary objects as messages</a>).</li>
<li>args (<a class="reference internal" href="stdtypes.html#tuple" title="tuple">tuple</a> | <a class="reference internal" href="stdtypes.html#dict" title="dict">dict</a>[<a class="reference internal" href="stdtypes.html#str" title="str">str</a>, <a class="reference internal" href="typing.html#typing.Any" title="typing.Any">Any</a>]) – Variable data to merge into the msg argument
to obtain the event description.</li>
<li>exc_info (<a class="reference internal" href="stdtypes.html#tuple" title="tuple">tuple</a>[<a class="reference internal" href="functions.html#type" title="type">type</a>[<a class="reference internal" href="exceptions.html#BaseException" title="BaseException">BaseException</a>], <a class="reference internal" href="exceptions.html#BaseException" title="BaseException">BaseException</a>, <a class="reference internal" href="types.html#types.TracebackType" title="types.TracebackType">types.TracebackType</a>] | None) – An exception tuple with the current exception information,
as returned by <a class="reference internal" href="sys.html#sys.exc_info" title="sys.exc_info"><code class="xref py py-func docutils literal notranslate">sys.exc_info()</code></a>,
or <code class="docutils literal notranslate">None</code> if no exception information is available.</li>
<li>func (<a class="reference internal" href="stdtypes.html#str" title="str">str</a> | None) – The name of the function or method
from which the logging call was invoked.</li>
<li>sinfo (<a class="reference internal" href="stdtypes.html#str" title="str">str</a> | None) – A text string representing stack information
from the base of the stack in the current thread,
up to the logging call.</li>
</ul>
</dd>
</dl>
<dl class="py method">
<dt class="sig sig-object py" id="logging.LogRecord.getMessage">
getMessage()<a class="headerlink" href="#logging.LogRecord.getMessage" title="Link to this definition">¶</a></dt>
<dd>Returns the message for this <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> instance after merging any
user-supplied arguments with the message. If the user-supplied message
argument to the logging call is not a string, <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-func docutils literal notranslate">str()</code></a> is called on it to
convert it to a string. This allows use of user-defined classes as
messages, whose <code class="docutils literal notranslate">__str__</code> method can return the actual format string to
be used.
</dd></dl>

<div class="versionchanged">
Changed in version 3.2: The creation of a <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> has been made more configurable by
providing a factory which is used to create the record. The factory can be
set using <a class="reference internal" href="#logging.getLogRecordFactory" title="logging.getLogRecordFactory"><code class="xref py py-func docutils literal notranslate">getLogRecordFactory()</code></a> and <a class="reference internal" href="#logging.setLogRecordFactory" title="logging.setLogRecordFactory"><code class="xref py py-func docutils literal notranslate">setLogRecordFactory()</code></a>
(see this for the factory’s signature).
</div>
This functionality can be used to inject your own values into a
<a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> at creation time. You can use the following pattern:
<div class="highlight-python3 notranslate"><div class="highlight"><pre>old_factory = logging.getLogRecordFactory()

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

logging.setLogRecordFactory(record_factory)
</pre></div>
</div>
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.
</dd></dl>

</section>
<section id="logrecord-attributes">
<h2>LogRecord attributes<a class="headerlink" href="#logrecord-attributes" title="Link to this heading">¶</a></h2>
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 (<a class="reference internal" href="stdtypes.html#str.format" title="str.format"><code class="xref py py-func docutils literal notranslate">str.format()</code></a>), you can use
<code class="docutils literal notranslate">{attrname}</code> as the placeholder in the format string. If you are using
$-formatting (<a class="reference internal" href="string.html#string.Template" title="string.Template"><code class="xref py py-class docutils literal notranslate">string.Template</code></a>), use the form <code class="docutils literal notranslate">${attrname}</code>. In
both cases, of course, replace <code class="docutils literal notranslate">attrname</code> 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 <code class="docutils literal notranslate">{msecs:03.0f}</code> would format a millisecond value of <code class="docutils literal notranslate">4</code> as
<code class="docutils literal notranslate">004</code>. Refer to the <a class="reference internal" href="stdtypes.html#str.format" title="str.format"><code class="xref py py-meth docutils literal notranslate">str.format()</code></a> documentation for full details on
the options available to you.
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head">Attribute name</th>
<th class="head">Format</th>
<th class="head">Description</th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td>args</td>
<td>You shouldn’t need to
format this yourself.</td>
<td>The tuple of arguments merged into <code class="docutils literal notranslate">msg</code> to
produce <code class="docutils literal notranslate">message</code>, or a dict whose values
are used for the merge (when there is only one
argument, and it is a dictionary).</td>
</tr>
<tr class="row-odd"><td>asctime</td>
<td><code class="docutils literal notranslate">%(asctime)s</code></td>
<td>Human-readable time when the
<a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> 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).</td>
</tr>
<tr class="row-even"><td>created</td>
<td><code class="docutils literal notranslate">%(created)f</code></td>
<td>Time when the <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> was created
(as returned by <a class="reference internal" href="time.html#time.time" title="time.time"><code class="xref py py-func docutils literal notranslate">time.time()</code></a>).</td>
</tr>
<tr class="row-odd"><td>exc_info</td>
<td>You shouldn’t need to
format this yourself.</td>
<td>Exception tuple (à la <code class="docutils literal notranslate">sys.exc_info</code>) or,
if no exception has occurred, <code class="docutils literal notranslate">None</code>.</td>
</tr>
<tr class="row-even"><td>filename</td>
<td><code class="docutils literal notranslate">%(filename)s</code></td>
<td>Filename portion of <code class="docutils literal notranslate">pathname</code>.</td>
</tr>
<tr class="row-odd"><td>funcName</td>
<td><code class="docutils literal notranslate">%(funcName)s</code></td>
<td>Name of function containing the logging call.</td>
</tr>
<tr class="row-even"><td>levelname</td>
<td><code class="docutils literal notranslate">%(levelname)s</code></td>
<td>Text logging level for the message
(<code class="docutils literal notranslate">'DEBUG'</code>, <code class="docutils literal notranslate">'INFO'</code>, <code class="docutils literal notranslate">'WARNING'</code>,
<code class="docutils literal notranslate">'ERROR'</code>, <code class="docutils literal notranslate">'CRITICAL'</code>).</td>
</tr>
<tr class="row-odd"><td>levelno</td>
<td><code class="docutils literal notranslate">%(levelno)s</code></td>
<td>Numeric logging level for the message
(<a class="reference internal" href="#logging.DEBUG" title="logging.DEBUG"><code class="xref py py-const docutils literal notranslate">DEBUG</code></a>, <a class="reference internal" href="#logging.INFO" title="logging.INFO"><code class="xref py py-const docutils literal notranslate">INFO</code></a>,
<a class="reference internal" href="#logging.WARNING" title="logging.WARNING"><code class="xref py py-const docutils literal notranslate">WARNING</code></a>, <a class="reference internal" href="#logging.ERROR" title="logging.ERROR"><code class="xref py py-const docutils literal notranslate">ERROR</code></a>,
<a class="reference internal" href="#logging.CRITICAL" title="logging.CRITICAL"><code class="xref py py-const docutils literal notranslate">CRITICAL</code></a>).</td>
</tr>
<tr class="row-even"><td>lineno</td>
<td><code class="docutils literal notranslate">%(lineno)d</code></td>
<td>Source line number where the logging call was
issued (if available).</td>
</tr>
<tr class="row-odd"><td>message</td>
<td><code class="docutils literal notranslate">%(message)s</code></td>
<td>The logged message, computed as <code class="docutils literal notranslate">msg %
args</code>. This is set when
<a class="reference internal" href="#logging.Formatter.format" title="logging.Formatter.format"><code class="xref py py-meth docutils literal notranslate">Formatter.format()</code></a> is invoked.</td>
</tr>
<tr class="row-even"><td>module</td>
<td><code class="docutils literal notranslate">%(module)s</code></td>
<td>Module (name portion of <code class="docutils literal notranslate">filename</code>).</td>
</tr>
<tr class="row-odd"><td>msecs</td>
<td><code class="docutils literal notranslate">%(msecs)d</code></td>
<td>Millisecond portion of the time when the
<a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> was created.</td>
</tr>
<tr class="row-even"><td>msg</td>
<td>You shouldn’t need to
format this yourself.</td>
<td>The format string passed in the original
logging call. Merged with <code class="docutils literal notranslate">args</code> to
produce <code class="docutils literal notranslate">message</code>, or an arbitrary object
(see <a class="reference internal" href="../howto/logging.html#arbitrary-object-messages">Using arbitrary objects as messages</a>).</td>
</tr>
<tr class="row-odd"><td>name</td>
<td><code class="docutils literal notranslate">%(name)s</code></td>
<td>Name of the logger used to log the call.</td>
</tr>
<tr class="row-even"><td>pathname</td>
<td><code class="docutils literal notranslate">%(pathname)s</code></td>
<td>Full pathname of the source file where the
logging call was issued (if available).</td>
</tr>
<tr class="row-odd"><td>process</td>
<td><code class="docutils literal notranslate">%(process)d</code></td>
<td>Process ID (if available).</td>
</tr>
<tr class="row-even"><td>processName</td>
<td><code class="docutils literal notranslate">%(processName)s</code></td>
<td>Process name (if available).</td>
</tr>
<tr class="row-odd"><td>relativeCreated</td>
<td><code class="docutils literal notranslate">%(relativeCreated)d</code></td>
<td>Time in milliseconds when the LogRecord was
created, relative to the time the logging
module was loaded.</td>
</tr>
<tr class="row-even"><td>stack_info</td>
<td>You shouldn’t need to
format this yourself.</td>
<td>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.</td>
</tr>
<tr class="row-odd"><td>thread</td>
<td><code class="docutils literal notranslate">%(thread)d</code></td>
<td>Thread ID (if available).</td>
</tr>
<tr class="row-even"><td>threadName</td>
<td><code class="docutils literal notranslate">%(threadName)s</code></td>
<td>Thread name (if available).</td>
</tr>
<tr class="row-odd"><td>taskName</td>
<td><code class="docutils literal notranslate">%(taskName)s</code></td>
<td><a class="reference internal" href="asyncio-task.html#asyncio.Task" title="asyncio.Task"><code class="xref py py-class docutils literal notranslate">asyncio.Task</code></a> name (if available).</td>
</tr>
</tbody>
</table>
<div class="versionchanged">
Changed in version 3.1: processName was added.
</div>
<div class="versionchanged">
Changed in version 3.12: taskName was added.
</div>
</section>
<section id="loggeradapter-objects">
<h2>LoggerAdapter Objects<a class="headerlink" href="#loggeradapter-objects" title="Link to this heading">¶</a></h2>
<a class="reference internal" href="#logging.LoggerAdapter" title="logging.LoggerAdapter"><code class="xref py py-class docutils literal notranslate">LoggerAdapter</code></a> instances are used to conveniently pass contextual
information into logging calls. For a usage example, see the section on
<a class="reference internal" href="../howto/logging-cookbook.html#context-info">adding contextual information to your logging output</a>.
<dl class="py class">
<dt class="sig sig-object py" id="logging.LoggerAdapter">
class logging.LoggerAdapter(logger, extra)<a class="headerlink" href="#logging.LoggerAdapter" title="Link to this definition">¶</a></dt>
<dd>Returns an instance of <a class="reference internal" href="#logging.LoggerAdapter" title="logging.LoggerAdapter"><code class="xref py py-class docutils literal notranslate">LoggerAdapter</code></a> initialized with an
underlying <a class="reference internal" href="#logging.Logger" title="logging.Logger"><code class="xref py py-class docutils literal notranslate">Logger</code></a> instance and a dict-like object.
<dl class="py method">
<dt class="sig sig-object py" id="logging.LoggerAdapter.process">
process(msg, kwargs)<a class="headerlink" href="#logging.LoggerAdapter.process" title="Link to this definition">¶</a></dt>
<dd>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.
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="logging.LoggerAdapter.manager">
manager<a class="headerlink" href="#logging.LoggerAdapter.manager" title="Link to this definition">¶</a></dt>
<dd>Delegates to the underlying <code class="xref py py-attr docutils literal notranslate">manager`</code> on logger.
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="logging.LoggerAdapter._log">
_log<a class="headerlink" href="#logging.LoggerAdapter._log" title="Link to this definition">¶</a></dt>
<dd>Delegates to the underlying <code class="xref py py-meth docutils literal notranslate">_log`()</code> method on logger.
</dd></dl>

In addition to the above, <a class="reference internal" href="#logging.LoggerAdapter" title="logging.LoggerAdapter"><code class="xref py py-class docutils literal notranslate">LoggerAdapter</code></a> supports the following
methods of <a class="reference internal" href="#logging.Logger" title="logging.Logger"><code class="xref py py-class docutils literal notranslate">Logger</code></a>: <a class="reference internal" href="#logging.Logger.debug" title="logging.Logger.debug"><code class="xref py py-meth docutils literal notranslate">debug()</code></a>, <a class="reference internal" href="#logging.Logger.info" title="logging.Logger.info"><code class="xref py py-meth docutils literal notranslate">info()</code></a>,
<a class="reference internal" href="#logging.Logger.warning" title="logging.Logger.warning"><code class="xref py py-meth docutils literal notranslate">warning()</code></a>, <a class="reference internal" href="#logging.Logger.error" title="logging.Logger.error"><code class="xref py py-meth docutils literal notranslate">error()</code></a>, <a class="reference internal" href="#logging.Logger.exception" title="logging.Logger.exception"><code class="xref py py-meth docutils literal notranslate">exception()</code></a>,
<a class="reference internal" href="#logging.Logger.critical" title="logging.Logger.critical"><code class="xref py py-meth docutils literal notranslate">critical()</code></a>, <a class="reference internal" href="#logging.Logger.log" title="logging.Logger.log"><code class="xref py py-meth docutils literal notranslate">log()</code></a>, <a class="reference internal" href="#logging.Logger.isEnabledFor" title="logging.Logger.isEnabledFor"><code class="xref py py-meth docutils literal notranslate">isEnabledFor()</code></a>,
<a class="reference internal" href="#logging.Logger.getEffectiveLevel" title="logging.Logger.getEffectiveLevel"><code class="xref py py-meth docutils literal notranslate">getEffectiveLevel()</code></a>, <a class="reference internal" href="#logging.Logger.setLevel" title="logging.Logger.setLevel"><code class="xref py py-meth docutils literal notranslate">setLevel()</code></a> and
<a class="reference internal" href="#logging.Logger.hasHandlers" title="logging.Logger.hasHandlers"><code class="xref py py-meth docutils literal notranslate">hasHandlers()</code></a>. These methods have the same signatures as their
counterparts in <a class="reference internal" href="#logging.Logger" title="logging.Logger"><code class="xref py py-class docutils literal notranslate">Logger</code></a>, so you can use the two types of instances
interchangeably.
<div class="versionchanged">
Changed in version 3.2: The <a class="reference internal" href="#logging.Logger.isEnabledFor" title="logging.Logger.isEnabledFor"><code class="xref py py-meth docutils literal notranslate">isEnabledFor()</code></a>, <a class="reference internal" href="#logging.Logger.getEffectiveLevel" title="logging.Logger.getEffectiveLevel"><code class="xref py py-meth docutils literal notranslate">getEffectiveLevel()</code></a>,
<a class="reference internal" href="#logging.Logger.setLevel" title="logging.Logger.setLevel"><code class="xref py py-meth docutils literal notranslate">setLevel()</code></a> and <a class="reference internal" href="#logging.Logger.hasHandlers" title="logging.Logger.hasHandlers"><code class="xref py py-meth docutils literal notranslate">hasHandlers()</code></a> methods were added
to <a class="reference internal" href="#logging.LoggerAdapter" title="logging.LoggerAdapter"><code class="xref py py-class docutils literal notranslate">LoggerAdapter</code></a>. These methods delegate to the underlying logger.
</div>
<div class="versionchanged">
Changed in version 3.6: Attribute <code class="xref py py-attr docutils literal notranslate">manager</code> and method <code class="xref py py-meth docutils literal notranslate">_log()</code> were added, which
delegate to the underlying logger and allow adapters to be nested.
</div>
</dd></dl>

</section>
<section id="thread-safety">
<h2>Thread Safety<a class="headerlink" href="#thread-safety" title="Link to this heading">¶</a></h2>
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 <a class="reference internal" href="signal.html#module-signal" title="signal: Set handlers for asynchronous events."><code class="xref py py-mod docutils literal notranslate">signal</code></a>
module, you may not be able to use logging from within such handlers. This is
because lock implementations in the <a class="reference internal" href="threading.html#module-threading" title="threading: Thread-based parallelism."><code class="xref py py-mod docutils literal notranslate">threading</code></a> module are not always
re-entrant, and so cannot be invoked from such signal handlers.
</section>
<section id="module-level-functions">
<h2>Module-Level Functions<a class="headerlink" href="#module-level-functions" title="Link to this heading">¶</a></h2>
In addition to the classes described above, there are a number of module-level
functions.
<dl class="py function">
<dt class="sig sig-object py" id="logging.getLogger">
logging.getLogger(name=None)<a class="headerlink" href="#logging.getLogger" title="Link to this definition">¶</a></dt>
<dd>Return a logger with the specified name or, if name is <code class="docutils literal notranslate">None</code>, 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.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.getLoggerClass">
logging.getLoggerClass()<a class="headerlink" href="#logging.getLoggerClass" title="Link to this definition">¶</a></dt>
<dd>Return either the standard <a class="reference internal" href="#logging.Logger" title="logging.Logger"><code class="xref py py-class docutils literal notranslate">Logger</code></a> class, or the last class passed to
<a class="reference internal" href="#logging.setLoggerClass" title="logging.setLoggerClass"><code class="xref py py-func docutils literal notranslate">setLoggerClass()</code></a>. This function may be called from within a new class
definition, to ensure that installing a customized <a class="reference internal" href="#logging.Logger" title="logging.Logger"><code class="xref py py-class docutils literal notranslate">Logger</code></a> class will
not undo customizations already applied by other code. For example:
<div class="highlight-python3 notranslate"><div class="highlight"><pre>class MyLogger(logging.getLoggerClass()):
 # ... override behaviour here
</pre></div>
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.getLogRecordFactory">
logging.getLogRecordFactory()<a class="headerlink" href="#logging.getLogRecordFactory" title="Link to this definition">¶</a></dt>
<dd>Return a callable which is used to create a <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a>.
<div class="versionadded">
New in version 3.2: This function has been provided, along with <a class="reference internal" href="#logging.setLogRecordFactory" title="logging.setLogRecordFactory"><code class="xref py py-func docutils literal notranslate">setLogRecordFactory()</code></a>,
to allow developers more control over how the <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a>
representing a logging event is constructed.
</div>
See <a class="reference internal" href="#logging.setLogRecordFactory" title="logging.setLogRecordFactory"><code class="xref py py-func docutils literal notranslate">setLogRecordFactory()</code></a> for more information about the how the
factory is called.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.debug">
logging.debug(msg, *args, **kwargs)<a class="headerlink" href="#logging.debug" title="Link to this definition">¶</a></dt>
<dd>This is a convenience function that calls <a class="reference internal" href="#logging.Logger.debug" title="logging.Logger.debug"><code class="xref py py-meth docutils literal notranslate">Logger.debug()</code></a>, on the root
logger. The handling of the arguments is in every way identical
to what is described in that method.
The only difference is that if the root logger has no handlers, then
<a class="reference internal" href="#logging.basicConfig" title="logging.basicConfig"><code class="xref py py-func docutils literal notranslate">basicConfig()</code></a> is called, prior to calling <code class="docutils literal notranslate">debug</code> on the root logger.
For very short scripts or quick demonstrations of <code class="docutils literal notranslate">logging</code> facilities,
<code class="docutils literal notranslate">debug</code> and the other module-level functions may be convenient. However,
most programs will want to carefully and explicitly control the logging
configuration, and should therefore prefer creating a module-level logger and
calling <a class="reference internal" href="#logging.Logger.debug" title="logging.Logger.debug"><code class="xref py py-meth docutils literal notranslate">Logger.debug()</code></a> (or other level-specific methods) on it, as
described at the beginnning of this documentation.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.info">
logging.info(msg, *args, **kwargs)<a class="headerlink" href="#logging.info" title="Link to this definition">¶</a></dt>
<dd>Logs a message with level <a class="reference internal" href="#logging.INFO" title="logging.INFO"><code class="xref py py-const docutils literal notranslate">INFO</code></a> on the root logger. The arguments and behavior
are otherwise the same as for <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-func docutils literal notranslate">debug()</code></a>.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.warning">
logging.warning(msg, *args, **kwargs)<a class="headerlink" href="#logging.warning" title="Link to this definition">¶</a></dt>
<dd>Logs a message with level <a class="reference internal" href="#logging.WARNING" title="logging.WARNING"><code class="xref py py-const docutils literal notranslate">WARNING</code></a> on the root logger. The arguments and behavior
are otherwise the same as for <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-func docutils literal notranslate">debug()</code></a>.
<div class="admonition note">
Note
There is an obsolete function <code class="docutils literal notranslate">warn</code> which is functionally
identical to <code class="docutils literal notranslate">warning</code>. As <code class="docutils literal notranslate">warn</code> is deprecated, please do not use
it - use <code class="docutils literal notranslate">warning</code> instead.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.error">
logging.error(msg, *args, **kwargs)<a class="headerlink" href="#logging.error" title="Link to this definition">¶</a></dt>
<dd>Logs a message with level <a class="reference internal" href="#logging.ERROR" title="logging.ERROR"><code class="xref py py-const docutils literal notranslate">ERROR</code></a> on the root logger. The arguments and behavior
are otherwise the same as for <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-func docutils literal notranslate">debug()</code></a>.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.critical">
logging.critical(msg, *args, **kwargs)<a class="headerlink" href="#logging.critical" title="Link to this definition">¶</a></dt>
<dd>Logs a message with level <a class="reference internal" href="#logging.CRITICAL" title="logging.CRITICAL"><code class="xref py py-const docutils literal notranslate">CRITICAL</code></a> on the root logger. The arguments and behavior
are otherwise the same as for <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-func docutils literal notranslate">debug()</code></a>.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.exception">
logging.exception(msg, *args, **kwargs)<a class="headerlink" href="#logging.exception" title="Link to this definition">¶</a></dt>
<dd>Logs a message with level <a class="reference internal" href="#logging.ERROR" title="logging.ERROR"><code class="xref py py-const docutils literal notranslate">ERROR</code></a> on the root logger. The arguments and behavior
are otherwise the same as for <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-func docutils literal notranslate">debug()</code></a>. Exception info is added to the logging
message. This function should only be called from an exception handler.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.log">
logging.log(level, msg, *args, **kwargs)<a class="headerlink" href="#logging.log" title="Link to this definition">¶</a></dt>
<dd>Logs a message with level level on the root logger. The arguments and behavior
are otherwise the same as for <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-func docutils literal notranslate">debug()</code></a>.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.disable">
logging.disable(level=CRITICAL)<a class="headerlink" href="#logging.disable" title="Link to this definition">¶</a></dt>
<dd>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
<code class="docutils literal notranslate">logging.disable(logging.NOTSET)</code> 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
<code class="docutils literal notranslate">CRITICAL</code> (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.
<div class="versionchanged">
Changed in version 3.7: The level parameter was defaulted to level <code class="docutils literal notranslate">CRITICAL</code>. See
<a class="reference external" href="https://bugs.python.org/issue?&#64;action=redirect&amp;bpo=28524">bpo-28524</a> for more information about this change.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.addLevelName">
logging.addLevelName(level, levelName)<a class="headerlink" href="#logging.addLevelName" title="Link to this definition">¶</a></dt>
<dd>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
<a class="reference internal" href="#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate">Formatter</code></a> formats a message. This function can also be used to define
your own levels. 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.
<div class="admonition note">
Note
If you are thinking of defining your own levels, please see the
section on <a class="reference internal" href="../howto/logging.html#custom-levels">Custom Levels</a>.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.getLevelNamesMapping">
logging.getLevelNamesMapping()<a class="headerlink" href="#logging.getLevelNamesMapping" title="Link to this definition">¶</a></dt>
<dd>Returns a mapping from level names to their corresponding logging levels. For example, the
string “CRITICAL” maps to <a class="reference internal" href="#logging.CRITICAL" title="logging.CRITICAL"><code class="xref py py-const docutils literal notranslate">CRITICAL</code></a>. The returned mapping is copied from an internal
mapping on each call to this function.
<div class="versionadded">
New in version 3.11.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.getLevelName">
logging.getLevelName(level)<a class="headerlink" href="#logging.getLevelName" title="Link to this definition">¶</a></dt>
<dd>Returns the textual or numeric representation of logging level level.
If level is one of the predefined levels <a class="reference internal" href="#logging.CRITICAL" title="logging.CRITICAL"><code class="xref py py-const docutils literal notranslate">CRITICAL</code></a>, <a class="reference internal" href="#logging.ERROR" title="logging.ERROR"><code class="xref py py-const docutils literal notranslate">ERROR</code></a>,
<a class="reference internal" href="#logging.WARNING" title="logging.WARNING"><code class="xref py py-const docutils literal notranslate">WARNING</code></a>, <a class="reference internal" href="#logging.INFO" title="logging.INFO"><code class="xref py py-const docutils literal notranslate">INFO</code></a> or <a class="reference internal" href="#logging.DEBUG" title="logging.DEBUG"><code class="xref py py-const docutils literal notranslate">DEBUG</code></a> then you get the
corresponding string. If you have associated levels with names using
<a class="reference internal" href="#logging.addLevelName" title="logging.addLevelName"><code class="xref py py-func docutils literal notranslate">addLevelName()</code></a> 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.
<div class="admonition note">
Note
Levels are internally integers (as they need to be compared in the
logging logic). This function is used to convert between an integer level
and the level name displayed in the formatted log output by means of the
<code class="docutils literal notranslate">%(levelname)s</code> format specifier (see <a class="reference internal" href="#logrecord-attributes">LogRecord attributes</a>), and
vice versa.
</div>
<div class="versionchanged">
Changed in version 3.4: 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.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.getHandlerByName">
logging.getHandlerByName(name)<a class="headerlink" href="#logging.getHandlerByName" title="Link to this definition">¶</a></dt>
<dd>Returns a handler with the specified name, or <code class="docutils literal notranslate">None</code> if there is no handler
with that name.
<div class="versionadded">
New in version 3.12.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.getHandlerNames">
logging.getHandlerNames()<a class="headerlink" href="#logging.getHandlerNames" title="Link to this definition">¶</a></dt>
<dd>Returns an immutable set of all known handler names.
<div class="versionadded">
New in version 3.12.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.makeLogRecord">
logging.makeLogRecord(attrdict)<a class="headerlink" href="#logging.makeLogRecord" title="Link to this definition">¶</a></dt>
<dd>Creates and returns a new <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> instance whose attributes are
defined by attrdict. This function is useful for taking a pickled
<a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> attribute dictionary, sent over a socket, and reconstituting
it as a <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> instance at the receiving end.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.basicConfig">
logging.basicConfig(**kwargs)<a class="headerlink" href="#logging.basicConfig" title="Link to this definition">¶</a></dt>
<dd>Does basic configuration for the logging system by creating a
<a class="reference internal" href="logging.handlers.html#logging.StreamHandler" title="logging.StreamHandler"><code class="xref py py-class docutils literal notranslate">StreamHandler</code></a> with a default <a class="reference internal" href="#logging.Formatter" title="logging.Formatter"><code class="xref py py-class docutils literal notranslate">Formatter</code></a> and adding it to the
root logger. The functions <a class="reference internal" href="#logging.debug" title="logging.debug"><code class="xref py py-func docutils literal notranslate">debug()</code></a>, <a class="reference internal" href="#logging.info" title="logging.info"><code class="xref py py-func docutils literal notranslate">info()</code></a>, <a class="reference internal" href="#logging.warning" title="logging.warning"><code class="xref py py-func docutils literal notranslate">warning()</code></a>,
<a class="reference internal" href="#logging.error" title="logging.error"><code class="xref py py-func docutils literal notranslate">error()</code></a> and <a class="reference internal" href="#logging.critical" title="logging.critical"><code class="xref py py-func docutils literal notranslate">critical()</code></a> will call <a class="reference internal" href="#logging.basicConfig" title="logging.basicConfig"><code class="xref py py-func docutils literal notranslate">basicConfig()</code></a> 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 <code class="docutils literal notranslate">True</code>.
<div class="admonition note">
Note
This function should be called from the main thread
before other threads are started. 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.
</div>
The following keyword arguments are supported.
<table class="docutils align-default">
<thead>
<tr class="row-odd"><th class="head">Format</th>
<th class="head">Description</th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td>filename</td>
<td>Specifies that a <a class="reference internal" href="logging.handlers.html#logging.FileHandler" title="logging.FileHandler"><code class="xref py py-class docutils literal notranslate">FileHandler</code></a> be
created, using the specified filename,
rather than a <a class="reference internal" href="logging.handlers.html#logging.StreamHandler" title="logging.StreamHandler"><code class="xref py py-class docutils literal notranslate">StreamHandler</code></a>.</td>
</tr>
<tr class="row-odd"><td>filemode</td>
<td>If filename is specified, open the file
in this <a class="reference internal" href="functions.html#filemodes">mode</a>. Defaults
to <code class="docutils literal notranslate">'a'</code>.</td>
</tr>
<tr class="row-even"><td>format</td>
<td>Use the specified format string for the
handler. Defaults to attributes
<code class="docutils literal notranslate">levelname</code>, <code class="docutils literal notranslate">name</code> and <code class="docutils literal notranslate">message</code>
separated by colons.</td>
</tr>
<tr class="row-odd"><td>datefmt</td>
<td>Use the specified date/time format, as
accepted by <a class="reference internal" href="time.html#time.strftime" title="time.strftime"><code class="xref py py-func docutils literal notranslate">time.strftime()</code></a>.</td>
</tr>
<tr class="row-even"><td>style</td>
<td>If format is specified, use this style
for the format string. One of <code class="docutils literal notranslate">'%'</code>,
<code class="docutils literal notranslate">'{'</code> or <code class="docutils literal notranslate">'$'</code> for <a class="reference internal" href="stdtypes.html#old-string-formatting">printf-style</a>,
<a class="reference internal" href="stdtypes.html#str.format" title="str.format"><code class="xref py py-meth docutils literal notranslate">str.format()</code></a> or
<a class="reference internal" href="string.html#string.Template" title="string.Template"><code class="xref py py-class docutils literal notranslate">string.Template</code></a> respectively.
Defaults to <code class="docutils literal notranslate">'%'</code>.</td>
</tr>
<tr class="row-odd"><td>level</td>
<td>Set the root logger level to the specified
<a class="reference internal" href="#levels">level</a>.</td>
</tr>
<tr class="row-even"><td>stream</td>
<td>Use the specified stream to initialize the
<a class="reference internal" href="logging.handlers.html#logging.StreamHandler" title="logging.StreamHandler"><code class="xref py py-class docutils literal notranslate">StreamHandler</code></a>. Note that this
argument is incompatible with filename -
if both are present, a <code class="docutils literal notranslate">ValueError</code> is
raised.</td>
</tr>
<tr class="row-odd"><td>handlers</td>
<td>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 <code class="docutils literal notranslate">ValueError</code> is raised.</td>
</tr>
<tr class="row-even"><td>force</td>
<td>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.</td>
</tr>
<tr class="row-odd"><td>encoding</td>
<td>If this keyword argument is specified along
with filename, its value is used when the
<a class="reference internal" href="logging.handlers.html#logging.FileHandler" title="logging.FileHandler"><code class="xref py py-class docutils literal notranslate">FileHandler</code></a> is created, and thus
used when opening the output file.</td>
</tr>
<tr class="row-even"><td>errors</td>
<td>If this keyword argument is specified along
with filename, its value is used when the
<a class="reference internal" href="logging.handlers.html#logging.FileHandler" title="logging.FileHandler"><code class="xref py py-class docutils literal notranslate">FileHandler</code></a> is created, and thus
used when opening the output file. If not
specified, the value ‘backslashreplace’ is
used. Note that if <code class="docutils literal notranslate">None</code> is specified,
it will be passed as such to <a class="reference internal" href="functions.html#open" title="open"><code class="xref py py-func docutils literal notranslate">open()</code></a>,
which means that it will be treated the
same as passing ‘errors’.</td>
</tr>
</tbody>
</table>
<div class="versionchanged">
Changed in version 3.2: The style argument was added.
</div>
<div class="versionchanged">
Changed in version 3.3: 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).
</div>
<div class="versionchanged">
Changed in version 3.8: The force argument was added.
</div>
<div class="versionchanged">
Changed in version 3.9: The encoding and errors arguments were added.
</div>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.shutdown">
logging.shutdown()<a class="headerlink" href="#logging.shutdown" title="Link to this definition">¶</a></dt>
<dd>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 <a class="reference internal" href="atexit.html#module-atexit" title="atexit: Register and execute cleanup functions."><code class="xref py py-mod docutils literal notranslate">atexit</code></a>), so normally there’s no need to do that
manually.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.setLoggerClass">
logging.setLoggerClass(klass)<a class="headerlink" href="#logging.setLoggerClass" title="Link to this definition">¶</a></dt>
<dd>Tells the logging system to use the class klass when instantiating a logger.
The class should define <code class="xref py py-meth docutils literal notranslate">__init__()</code> such that only a name argument is
required, and the <code class="xref py py-meth docutils literal notranslate">__init__()</code> should call <code class="xref py py-meth docutils literal notranslate">Logger.__init__()</code>. 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 <a class="reference internal" href="#logging.getLogger" title="logging.getLogger"><code class="xref py py-func docutils literal notranslate">logging.getLogger()</code></a> API to get your loggers.
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="logging.setLogRecordFactory">
logging.setLogRecordFactory(factory)<a class="headerlink" href="#logging.setLogRecordFactory" title="Link to this definition">¶</a></dt>
<dd>Set a callable which is used to create a <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a>.
<dl class="field-list simple">
<dt class="field-odd">Parameters:</dt>
<dd class="field-odd">factory – The factory callable to be used to instantiate a log record.
</dd>
</dl>
<div class="versionadded">
New in version 3.2: This function has been provided, along with <a class="reference internal" href="#logging.getLogRecordFactory" title="logging.getLogRecordFactory"><code class="xref py py-func docutils literal notranslate">getLogRecordFactory()</code></a>, to
allow developers more control over how the <a class="reference internal" href="#logging.LogRecord" title="logging.LogRecord"><code class="xref py py-class docutils literal notranslate">LogRecord</code></a> representing
a logging event is constructed.
</div>
The factory has the following signature:
<code class="docutils literal notranslate">factory(name, level, fn, lno, msg, args, exc_info, func=None, sinfo=None, **kwargs)</code>
<blockquote>
<div><dl class="field-list simple">
<dt class="field-odd">name:</dt>
<dd class="field-odd">The logger name.
</dd>
<dt class="field-even">level:</dt>
<dd class="field-even">The logging level (numeric).
</dd>
<dt class="field-odd">fn:</dt>
<dd class="field-odd">The full pathname of the file where the logging call was made.
</dd>
<dt class="field-even">lno:</dt>
<dd class="field-even">The line number in the file where the logging call was made.
</dd>
<dt class="field-odd">msg:</dt>
<dd class="field-odd">The logging message.
</dd>
<dt class="field-even">args:</dt>
<dd class="field-even">The arguments for the logging message.
</dd>
<dt class="field-odd">exc_info:</dt>
<dd class="field-odd">An exception tuple, or <code class="docutils literal notranslate">None</code>.
</dd>
<dt class="field-even">func:</dt>
<dd class="field-even">The name of the function or method which invoked the logging
call.
</dd>
<dt class="field-odd">sinfo:</dt>
<dd class="field-odd">A stack traceback such as is provided by
<a class="reference internal" href="traceback.html#traceback.print_stack" title="traceback.print_stack"><code class="xref py py-func docutils literal notranslate">traceback.print_stack()</code></a>, showing the call hierarchy.
</dd>
<dt class="field-even">kwargs:</dt>
<dd class="field-even">Additional keyword arguments.
</dd>
</dl>
</div></blockquote>
</dd></dl>

</section>
<section id="module-level-attributes">
<h2>Module-Level Attributes<a class="headerlink" href="#module-level-attributes" title="Link to this heading">¶</a></h2>
<dl class="py attribute">
<dt class="sig sig-object py" id="logging.lastResort">
logging.lastResort<a class="headerlink" href="#logging.lastResort" title="Link to this definition">¶</a></dt>
<dd>A “handler of last resort” is available through this attribute. This
is a <a class="reference internal" href="logging.handlers.html#logging.StreamHandler" title="logging.StreamHandler"><code class="xref py py-class docutils literal notranslate">StreamHandler</code></a> writing to <code class="docutils literal notranslate">sys.stderr</code> with a level of
<code class="docutils literal notranslate">WARNING</code>, and is used to handle logging events in the absence of any
logging configuration. The end result is to just print the message to
<code class="docutils literal notranslate">sys.stderr</code>. 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, <code class="docutils literal notranslate">lastResort</code> can be set to <code class="docutils literal notranslate">None</code>.
<div class="versionadded">
New in version 3.2.
</div>
</dd></dl>

<dl class="py attribute">
<dt class="sig sig-object py" id="logging.raiseExceptions">
logging.raiseExceptions<a class="headerlink" href="#logging.raiseExceptions" title="Link to this definition">¶</a></dt>
<dd>Used to see if exceptions during handling should be propagated.
Default: <code class="docutils literal notranslate">True</code>.
If <a class="reference internal" href="#logging.raiseExceptions" title="logging.raiseExceptions"><code class="xref py py-data docutils literal notranslate">raiseExceptions</code></a> is <code class="docutils literal notranslate">False</code>,
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.
</dd></dl>

</section>
<section id="integration-with-the-warnings-module">
<h2>Integration with the warnings module<a class="headerlink" href="#integration-with-the-warnings-module" title="Link to this heading">¶</a></h2>
The <a class="reference internal" href="#logging.captureWarnings" title="logging.captureWarnings"><code class="xref py py-func docutils literal notranslate">captureWarnings()</code></a> function can be used to integrate <a class="reference internal" href="#module-logging" title="logging: Flexible event logging system for applications."><code class="xref py py-mod docutils literal notranslate">logging</code></a>
with the <a class="reference internal" href="warnings.html#module-warnings" title="warnings: Issue warning messages and control their disposition."><code class="xref py py-mod docutils literal notranslate">warnings</code></a> module.
<dl class="py function">
<dt class="sig sig-object py" id="logging.captureWarnings">
logging.captureWarnings(capture)<a class="headerlink" href="#logging.captureWarnings" title="Link to this definition">¶</a></dt>
<dd>This function is used to turn the capture of warnings by logging on and
off.
If capture is <code class="docutils literal notranslate">True</code>, warnings issued by the <a class="reference internal" href="warnings.html#module-warnings" title="warnings: Issue warning messages and control their disposition."><code class="xref py py-mod docutils literal notranslate">warnings</code></a> module will
be redirected to the logging system. Specifically, a warning will be
formatted using <a class="reference internal" href="warnings.html#warnings.formatwarning" title="warnings.formatwarning"><code class="xref py py-func docutils literal notranslate">warnings.formatwarning()</code></a> and the resulting string
logged to a logger named <code class="docutils literal notranslate">'py.warnings'</code> with a severity of <a class="reference internal" href="#logging.WARNING" title="logging.WARNING"><code class="xref py py-const docutils literal notranslate">WARNING</code></a>.
If capture is <code class="docutils literal notranslate">False</code>, 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 <code class="docutils literal notranslate">captureWarnings(True)</code> was called).
</dd></dl>

<div class="admonition seealso">
See also
<dl class="simple">
<dt>Module <a class="reference internal" href="logging.config.html#module-logging.config" title="logging.config: Configuration of the logging module."><code class="xref py py-mod docutils literal notranslate">logging.config</code></a></dt><dd>Configuration API for the logging module.
</dd>
<dt>Module <a class="reference internal" href="logging.handlers.html#module-logging.handlers" title="logging.handlers: Handlers for the logging module."><code class="xref py py-mod docutils literal notranslate">logging.handlers</code></a></dt><dd>Useful handlers included with the logging module.
</dd>
<dt><a class="pep reference external" href="https://peps.python.org/pep-0282/">PEP 282</a> - A Logging System</dt><dd>The proposal which described this feature for inclusion in the Python standard
library.
</dd>
<dt><a class="reference external" href="https://old.red-dove.com/python_logging.html">Original Python logging package</a></dt><dd>This is the original source for the <a class="reference internal" href="#module-logging" title="logging: Flexible event logging system for applications."><code class="xref py py-mod docutils literal notranslate">logging</code></a> 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 <a class="reference internal" href="#module-logging" title="logging: Flexible event logging system for applications."><code class="xref py py-mod docutils literal notranslate">logging</code></a> package in the standard
library.
</dd>
</dl>
</div>
</section>
</section>

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 <h3><a href="../contents.html">Table of Contents</a></h3>
 <ul>
<li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate">logging</code> — Logging facility for Python</a><ul>
<li><a class="reference internal" href="#logger-objects">Logger Objects</a></li>
<li><a class="reference internal" href="#logging-levels">Logging Levels</a></li>
<li><a class="reference internal" href="#handler-objects">Handler Objects</a></li>
<li><a class="reference internal" href="#formatter-objects">Formatter Objects</a></li>
<li><a class="reference internal" href="#filter-objects">Filter Objects</a></li>
<li><a class="reference internal" href="#logrecord-objects">LogRecord Objects</a></li>
<li><a class="reference internal" href="#logrecord-attributes">LogRecord attributes</a></li>
<li><a class="reference internal" href="#loggeradapter-objects">LoggerAdapter Objects</a></li>
<li><a class="reference internal" href="#thread-safety">Thread Safety</a></li>
<li><a class="reference internal" href="#module-level-functions">Module-Level Functions</a></li>
<li><a class="reference internal" href="#module-level-attributes">Module-Level Attributes</a></li>
<li><a class="reference internal" href="#integration-with-the-warnings-module">Integration with the warnings module</a></li>
</ul>
</li>
</ul>

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