Python module “logging” double output

I want to use the logging module, but I'm having some trouble because it is outputting twice. I've read a lot of posts with people having the same issue and log.propagate = False or `log.handlers.pop()´ fixed it for them. This doesn't work for me.

logging

log.propagate = False

I have a file called logger.py that looks like this:

import logging

def __init__():
log = logging.getLogger("output")
filelog = logging.FileHandler("output.log")
formatlog = logging.Formatter("%(asctime)s %(levelname)s %(message)s")
filelog.setFormatter(formatlog)
log.addHandler(filelog)
log.setLevel(logging.INFO)

return log


So that I from multiple files can write:

import logger
log = logger.__init__()


But this is giving me issues. So I've seen several solutions, but I don't know how to incorporate it in multiple scripts without defining the logger in all of them.

output.log

log.propagate = False

output.log

log.propagate = False

propagate

2 Answers
2

multiple scripts lead to multiple processes. so you unluckily create multiple objects returned from the logger.__init__() function.

logger.__init__()

usually, you have one script which creates the logger and the different processes,
but as i understand, you like to have multiple scripts logging to the same destination.

if you like to have multiple processes to log to the same destination, i recommend using inter process communication as "named pipes" or otherwise using a UDP/TCP port for logging.

There are also queue modules available in python to send a (atomic) logging entry to be logged in one part (compared to append to a file by multiple processes - which may lead from 111111n and 22222n to 11212121221nn in the file)

otherwise think about named pipes...

Code snippet for logging server
Note: i just assumed to log everything as error...

import socket
import logging

class mylogger():
def __init__(self, port=5005):
log = logging.getLogger("output")
filelog = logging.FileHandler("output.log")
formatlog = logging.Formatter("%(asctime)s %(levelname)s %(message)s")
filelog.setFormatter(formatlog)
log.addHandler(filelog)
log.setLevel(logging.INFO)
self.log = log
UDP_IP = "127.0.0.1" # localhost
self.port = port
self.UDPClientSocket = socket.socket(family=socket.AF_INET, type=socket.SOCK_DGRAM)
self.UDPClientSocket.bind((UDP_IP, self.port))
def pollReceive(self):
data, addr = self.UDPClientSocket.recvfrom(1024) # buffer size is 1024 bytes
print("received message:", data)
self.log.error( data )
pass

log = mylogger()

while True:
log.pollReceive()


I found a solution which was really simple. All I needed to do was to add an if statement checking if the handlers already existed. So my logger.py file now looks like this:

if

logger.py

import logging

def __init__():
log = logging.getLogger("output")

if not log.handlers:
filelog = logging.FileHandler("output.log")
formatlog = logging.Formatter("%(asctime)s %(levelname)s %(message)s")
filelog.setFormatter(formatlog)
log.addHandler(filelog)
log.setLevel(logging.INFO)

return log


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