New submission from eric:
If I have interpreted the python3 documentation correctly, regardless of where
I add the handler to the root logger, my log messages from within a Process
should be sent to a file. However, this is not the case.
Here is a complete program which demonstrates the problem:
import logging
import logging.handlers
from multiprocessing import Process
from time import sleep
fileHandler = logging.FileHandler( 'mylog.log' )
fileHandler.setLevel( 5 )
logger = logging.getLogger( None )
def process_logger():
print( "process waiting" )
sleep( 5 )
print( 'process start' )
logger = logging.getLogger( None )
for num in range( 1, 10 ):
logger.critical( "critical: %d" % num )
sleep(1)
#
# if this is where the handler is added, the critical messages
# will go to the file
#
logger.addHandler( fileHandler )
processLogger = Process( target=process_logger )
processLogger.start()
#
# if this is where the handler is added, the critical messages
# will not go to the file.
#
#logger.addHandler( fileHandler )
print( "started" )
I am using python 3.4.3 on OS X 10.10.4.
My guess as to why this does not work is that when I start the Process, it
makes a copy of the current environment and if the handler has not been added
by that time, the environment the Process is running in won't have it.
I have three questions:
Why do my messages not always end up in the file regardless of where I call
logger.addHandler?
Should my messages always end up in the file?
If they should not, what is the best solution to the general problem of needed
to manipulate handlers after a Process has been started?
----------
components: Extension Modules
messages: 247336
nosy: ericg97477
priority: normal
severity: normal
status: open
title: python logging handler not used when added after a process is started
versions: Python 3.4
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue24717>
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