一个简单的扩展不需要datetime模块，也不像其他解决方案那样受到限制，它使用简单的字符串替换，如下所示:

import logging
import time

class MyFormatter(logging.Formatter):
    def formatTime(self, record, datefmt=None):
        ct = self.converter(record.created)
        if datefmt:
            if "%F" in datefmt:
                msec = "%03d" % record.msecs
                datefmt = datefmt.replace("%F", msec)
            s = time.strftime(datefmt, ct)
        else:
            t = time.strftime("%Y-%m-%d %H:%M:%S", ct)
            s = "%s,%03d" % (t, record.msecs)
        return s

通过使用%F表示毫秒，可以任意编写日期格式，甚至允许区域差异。例如:

log = logging.getLogger(__name__)
log.setLevel(logging.INFO)

sh = logging.StreamHandler()
log.addHandler(sh)

fm = MyFormatter(fmt='%(asctime)s-%(levelname)s-%(message)s',datefmt='%H:%M:%S.%F')
sh.setFormatter(fm)

log.info("Foo, Bar, Baz")
# 03:26:33.757-INFO-Foo, Bar, Baz

如果你用箭头或者不介意用箭头的话。你可以用python的时间格式代替arrow的时间格式。

import logging

from arrow.arrow import Arrow


class ArrowTimeFormatter(logging.Formatter):

    def formatTime(self, record, datefmt=None):
        arrow_time = Arrow.fromtimestamp(record.created)

        if datefmt:
            arrow_time = arrow_time.format(datefmt)

        return str(arrow_time)


logger = logging.getLogger(__name__)

default_handler = logging.StreamHandler()
default_handler.setFormatter(ArrowTimeFormatter(
    fmt='%(asctime)s',
    datefmt='YYYY-MM-DD HH:mm:ss.SSS'
))

logger.setLevel(logging.DEBUG)
logger.addHandler(default_handler)

现在你可以在datefmt属性中使用箭头的所有时间格式。

这也可以工作:

logging.Formatter(
    fmt='%(asctime)s.%(msecs)03d',
    datefmt='%Y-%m-%d,%H:%M:%S'
)

我找到的最简单的方法是覆盖default_msec_format:

formatter = logging.Formatter('%(asctime)s')
formatter.default_msec_format = '%s.%03d'

实例化Formatter后，我通常设置Formatter。Converter = gmtime。所以为了让@unutbu的答案在这种情况下工作，你需要:

class MyFormatter(logging.Formatter):
    def formatTime(self, record, datefmt=None):
        ct = self.converter(record.created)
        if datefmt:
            s = time.strftime(datefmt, ct)
        else:
            t = time.strftime("%Y-%m-%d %H:%M:%S", ct)
            s = "%s.%03d" % (t, record.msecs)
        return s

请注意克雷格·麦克丹尼尔的解决方案显然更好。

日志记录。Formatter的formatTime方法看起来像这样:

def formatTime(self, record, datefmt=None):
    ct = self.converter(record.created)
    if datefmt:
        s = time.strftime(datefmt, ct)
    else:
        t = time.strftime("%Y-%m-%d %H:%M:%S", ct)
        s = "%s,%03d" % (t, record.msecs)
    return s

注意“%s，%03d”中的逗号。这不能通过指定一个datefmt来解决，因为ct是一个时间。Struct_time和这些对象不记录毫秒。

如果我们改变ct的定义，使其成为一个datetime对象而不是struct_time对象，那么(至少在现代版本的Python中)我们可以调用ct。Strftime，然后我们可以使用%f格式化微秒:

import logging
import datetime as dt

class MyFormatter(logging.Formatter):
    converter=dt.datetime.fromtimestamp
    def formatTime(self, record, datefmt=None):
        ct = self.converter(record.created)
        if datefmt:
            s = ct.strftime(datefmt)
        else:
            t = ct.strftime("%Y-%m-%d %H:%M:%S")
            s = "%s,%03d" % (t, record.msecs)
        return s

logger = logging.getLogger(__name__)
logger.setLevel(logging.DEBUG)

console = logging.StreamHandler()
logger.addHandler(console)

formatter = MyFormatter(fmt='%(asctime)s %(message)s',datefmt='%Y-%m-%d,%H:%M:%S.%f')
console.setFormatter(formatter)

logger.debug('Jackdaws love my big sphinx of quartz.')
# 2011-06-09,07:12:36.553554 Jackdaws love my big sphinx of quartz.

或者，为了获得毫秒，将逗号改为小数点，并省略datefmt参数:

class MyFormatter(logging.Formatter):
    converter=dt.datetime.fromtimestamp
    def formatTime(self, record, datefmt=None):
        ct = self.converter(record.created)
        if datefmt:
            s = ct.strftime(datefmt)
        else:
            t = ct.strftime("%Y-%m-%d %H:%M:%S")
            s = "%s.%03d" % (t, record.msecs)
        return s

...
formatter = MyFormatter(fmt='%(asctime)s %(message)s')
...
logger.debug('Jackdaws love my big sphinx of quartz.')
# 2011-06-09 08:14:38.343 Jackdaws love my big sphinx of quartz.