Question

我正在尝试设计一个Python程序，使用日志记录模块记录所有未捕获的异常。我这样做是通过使用sys.excepthook函数来覆盖默认的异常处理。我注意到如果我直接从命令行运行程序，它工作正常，但如果我尝试导入该文件，它不起作用。似乎sys.excepthook函数不知道日志记录模块。这是一个例子：

#! /usr/bin/env python2.7
import logging, sys

logger = logging.getLogger()
logger.setLevel(logging.DEBUG)
logger.addHandler(logging.FileHandler("test.log"))

print "outside of exception handler: logger = %s" % logger

def handleException(excType, excValue, traceback):
    #global logger  # this function doesn't work whether or not I include this line
    print "inside exception handler: logger = %s" % logger
    logger.error("Uncaught exception", exc_info=(excType, excValue, traceback))

sys.excepthook = handleException

logger.debug("starting")
asdf    # create an exception

如果我从命令行（./loggingTest.py）运行它，它可以正常工作。记录异常，我看到了这个输出：

outside of exception handler: logger = <logging.RootLogger object at 0x7f2022eab950>
inside exception handler: logger = <logging.RootLogger object at 0x7f2022eab950>

但是，如果我运行Python解释器并尝试导入文件（import loggingTest），它会很奇怪。异常没有记录，我看到了：

outside of exception handler: logger = <logging.RootLogger object at 0x7f8ab04f3ad0>
inside exception handler: logger = None
Error in sys.excepthook:
Traceback (most recent call last):
  File "loggingTest.py", line 13, in handleException
    logger.error("Uncaught exception", exc_info=(excType, excValue, traceback))
AttributeError: 'NoneType' object has no attribute 'error'

Original exception was:
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "loggingTest.py", line 18, in <module>
    asdf    # create an exception
NameError: name 'asdf' is not defined

我可以通过在sys.excepthook中再次导入日志记录模块来解决这个问题，但我仍然很好奇：为什么会发生这种情况？

Answer 1

我将此问题报告为Python bug tracker上的错误。到目前为止，有人回答说Python 2.7和2.7.1之间肯定存在变化，他认为这是预期的行为。他建议这样做以记录所有异常：

def handleException(excType, excValue, traceback, logger=logger):
    logger.error("Uncaught exception", exc_info=(excType, excValue, traceback))

sys.excepthook = handleException

Answer 2

我无法重现您的错误，即使它发生在exhook.py中。这是exhook.py：

#! /usr/bin/env python2.7
import logging, sys, traceback as tb

logger = logging.getLogger()
logger.setLevel(logging.DEBUG)
logger.addHandler(logging.FileHandler("test.log"))

print "outside of exception handler: logger = %s" % logger

def handleException(excType, excValue, traceback):
    #global logger  # this function doesn't work whether or not I include this line
    tb.print_exception(excType, excValue, traceback)
    print "inside exception handler: logger = %s" % logger
    logger.error("Uncaught exception", exc_info=(excType, excValue, traceback))

sys.excepthook = handleException

raise Exception

然后：

Python 2.7 (r27:82525, Jul  4 2010, 09:01:59) [MSC v.1500 32 bit (Intel)] on win
32
Type "help", "copyright", "credits" or "license" for more information.
>>> import exhook
outside of exception handler: logger = <logging.RootLogger object at 0x02AB0A70>

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "exhook.py", line 18, in <module>
    raise Exception
Exception inside exception handler: logger = <logging.RootLogger object at 0x02AB0A70>

它运作得很好。这对你有用吗？

sys.excepthook在导入的模块中不起作用

2 个答案: