如何记录Python异常?

try:
    do_something()
except:
    # How can I log my exception here, complete with its traceback?

当前回答

未捕获的异常消息将发送到STDERR,因此,您可以使用任何用于运行Python脚本的shell将STDERR发送到文件中,而不是在Python中实现日志记录。在Bash脚本中,您可以使用输出重定向来实现这一点,如Bash指南中所述。

例子

附加错误文件,其他输出到终端:

./test.py 2>> mylog.log

覆盖交错的STDOUT和STDERR输出文件:

./test.py &> mylog.log

其他回答

下面是一个简单的例子,摘自python 2.6文档:

import logging
LOG_FILENAME = '/tmp/logging_example.out'
logging.basicConfig(filename=LOG_FILENAME,level=logging.DEBUG,)

logging.debug('This message should go to the log file')

要关闭其他可能在这里丢失的内容,在日志中捕获它的最佳方法是使用traceback.format_exc()调用,然后将该字符串拆分为每行,以便在生成的日志文件中捕获:

import logging
import sys
import traceback

try:
  ...
except Exception as ex:
  # could be done differently, just showing you can split it apart to capture everything individually
  ex_t = type(ex).__name__
  err = str(ex)
  err_msg = f'[{ex_t}] - {err}'
  logging.error(err_msg)

  # go through the trackback lines and individually add those to the log as an error
  for l in traceback.format_exc().splitlines():
    logging.error(l)

您可以使用记录器在任何级别(DEBUG, INFO,…)获得跟踪。注意使用日志记录。异常时,级别为ERROR。

# test_app.py
import sys
import logging

logging.basicConfig(level="DEBUG")

def do_something():
    raise ValueError(":(")

try:
    do_something()
except Exception:
    logging.debug("Something went wrong", exc_info=sys.exc_info())
DEBUG:root:Something went wrong
Traceback (most recent call last):
  File "test_app.py", line 10, in <module>
    do_something()
  File "test_app.py", line 7, in do_something
    raise ValueError(":(")
ValueError: :(

编辑:

这也可以(使用python 3.6)

logging.debug("Something went wrong", exc_info=True)

下面是一个使用sys.excepthook的版本

import traceback
import sys

logger = logging.getLogger()

def handle_excepthook(type, message, stack):
     logger.error(f'An unhandled exception occured: {message}. Traceback: {traceback.format_tb(stack)}')

sys.excepthook = handle_excepthook

使用日志记录。Exception:处理程序/块中的异常,以记录当前异常和跟踪信息,并添加一条消息。

import logging
LOG_FILENAME = '/tmp/logging_example.out'
logging.basicConfig(filename=LOG_FILENAME, level=logging.DEBUG)

logging.debug('This message should go to the log file')

try:
    run_my_stuff()
except:
    logging.exception('Got exception on main handler')
    raise

现在查看日志文件/tmp/logging_example.out:

DEBUG:root:This message should go to the log file
ERROR:root:Got exception on main handler
Traceback (most recent call last):
  File "/tmp/teste.py", line 9, in <module>
    run_my_stuff()
NameError: name 'run_my_stuff' is not defined