Python logging: different logging destination per process

Question

I just started to use Python logging module and I cannot understand something.

I'm writing a script that works in the following way:

1st part (single process): it get some data to compute (it's not important how). Here I create a logger in the following way:

import logging
logging.basicConfig(format='%(asctime)-6s: %(name)s - %(levelname)s - %(message)s')
logger = logging.getLogger('Pipeline')
logger.setLevel(logging.INFO)
logger.warning('Pipeline started')

In other words I log to the screen.

2nd part (multiprocessing): I create several processes (the data analysis is really time and CPU consuming) to analyze the data found before.

Now I would like that each process logs to a different file ONLY without logging to the screen.

What I wrote is :

fh = logging.FileHandler('/tmp/'+multiprocessing.current_process().name+'_worker.log')
fmt = logging.Formatter(%(asctime)-6s: %(name)s - %(levelname)s - %(message)s)
fh.setFormatter(fmt)
local_logger = logging.getLogger(multiprocessing.current_process().name+'_worker')
local_logger.addHandler(fh)
local_logger.warning(multiprocessing.current_process().name + ' (worker) Process started')

What I got is that each process logs to a different file but logs ALSO to the screen!

How can I fix this?

Answer 1

Suspect that your local logger is passing its log messages upwards to the top level, where it gets output to stdout. Try turning off propagation on the local logger. I believe you can do it like this:

local_logger.propagate = False

Answer 2

You could do it Art Swri's way, or just omit the basicConfig() call. That's what adds a console handler to the root logger.