如何使用日志库？ （在 Python 中实现日志记录）

Question

I would like to apply logging library in a class to get reports from the different steps in my code and use info , debug or error functions and keep it in a logging file. In addition I want to use multiprocessing in my code as well. But I could not quite figure out how it works and should be set up, plus I have used it in a code and defined it as following

import logging 

logging.basicConfig(filename='logfile.log',level=logging.DEBUG)

it halted the code and prevents to terminate the process. I am wondering how it should be used in a class and stopped and closed the log file?!! Any help would be appreciated...

Answer 1

You may go through Good logging practice in python for getting more idea of logging module and get more detailed info from Python document .

Below is a basic example on how to use logging module, in which I am knowingly raising an exception:

import logging
log = logging.getLogger("mylog")
log.setLevel(logging.DEBUG)

formatter = logging.Formatter(
    "%(asctime)s %(threadName)-11s %(levelname)-10s %(message)s")
# Alternative formatting available on python 3.2+:
# formatter = logging.Formatter(
#     "{asctime} {threadName:>11} {levelname} {message}", style='{')

# Log to file
filehandler = logging.FileHandler("debug.txt", "w")
filehandler.setLevel(logging.DEBUG)
filehandler.setFormatter(formatter)
log.addHandler(filehandler)

# Log to stdout too
streamhandler = logging.StreamHandler()
streamhandler.setLevel(logging.INFO)
streamhandler.setFormatter(formatter)
log.addHandler(streamhandler)

# Test it
log.debug("Some message")
log.error("An error!")
try:
    something()
except:
    log.exception("An exception occured!")

In your debug.txt , you will get output as:

2011-01-18 12:07:24,943  MainThread  DEBUG      Some message
2011-01-18 12:07:24,943  MainThread  ERROR      An error!
2011-01-18 12:07:24,943  MainThread  ERROR      An exception occured!
Traceback (most recent call last):
  File "./logtest.py", line 17, in 
    something()
NameError: name 'something' is not defined

Answer 2

For my own projects I developed logging tool that helps me a lot.
The repository allows to set a config file or to define your preferences in the code. My way of approaching in a new script is:
1. copy the file `MyLogger.py` in your root directory 2. in the files where you want to log something do: ``` // script.py from MyLogger import Logger

log = Logger( name ).logger

log.info('hello')

 The output of the logger will even contain the namefile (script.py). <br> I hope it helps! <br> The <a href="https://github.com/vignif/LogMe">code is available</a>