使用python记录器捕获非python第三方库的输出

Question

我已经编写了一个使用logging模块的Python包，并广泛使用了带有Python包装的第三方C++库。我已经能够将自己包中的消息打印到控制台，并将它们写入文件(每个处理程序的日志记录级别不同(。但是，我希望将第三方库打印的消息包含在日志文件中，以便查看它们的出现顺序。这是我的MWE:

import logging
# Assume no direct access to this function. (e.g. c++ library)
def third_party_function():
print("Inside of 'third_party_function'.")
def my_helper():
logger.debug("Inside of 'my_helper', before third party call.")
third_party_function()
logger.warning("Finished with third party call.")
root_logger = logging.getLogger()
root_logger.setLevel(logging.NOTSET)
logger = logging.getLogger("mylogger")
stream_handler = logging.StreamHandler()
stream_handler.setLevel(logging.WARNING)
file_handler = logging.FileHandler(filename="progress.out")
file_handler.setLevel(logging.NOTSET)
logger.addHandler(stream_handler)
logger.addHandler(file_handler)
my_helper()

目前，屏幕的输出为：

Inside of 'third_party_function'.
Finished with third party call.

文件CCD_ 2包含

Inside of 'my_helper', before third party call.
Finished with third party call.

但是，所需的progress.out文件是

Inside of 'my_helper', before third party call.
Inside of 'third_party_function'.
Finished with third party call.

似乎没有属于这个第三方库的记录器，因为它不是用Python编写的。

我希望避免将sys.stdout设置为文件(如这里所示(，因为我希望保持一致并始终使用logging模块。同一个问题的另一个答案定义了一个自定义类，但这似乎仍然没有捕捉到第三方消息。

Answer 1

您可以暂时将第三方函数的stdout重定向到记录器。

使用您链接的答案中的StreamToLogger类：重定向Python'；打印'；记录器的输出

def wrap_third_party_function():
stdout = sys.stdout # save for restoring afterwards
# redirect stdout to use a logger, with INFO level
sys.stdout = StreamToLogger(logging.getLogger("mylogger.thirdparty"), logging.INFO)
print("start third_party_function; stdout to log")
third_party_function()
sys.stdout = stdout  # restore stdout
print("done third_party_function; stdout restored")
def my_helper():
logger.debug("Inside of 'my_helper', before third party call.")
wrap_third_party_function()
logger.warning("Finished with third party call.")

在控制台上，你会得到这个：

done third_party_function; stdout restored
Finished with third party call.

而progress.out将有：

Inside of 'my_helper', before third party call.
start third_party_function; stdout to log
Inside of 'third_party_function'.
Finished with third party call.

添加格式化程序使其更容易查看：

formatter = logging.Formatter("%(name)s %(levelname)-8s %(message)s")
stream_handler.setFormatter(formatter)
file_handler.setFormatter(formatter)

使用此配置，progress.out显示：

mylogger DEBUG    Inside of 'my_helper', before third party call.
mylogger.thirdparty INFO     start third_party_function; stdout to log
mylogger.thirdparty INFO     Inside of 'third_party_function'.
mylogger WARNING  Finished with third party call.