[ Python module threading as daemon with logging ]

I try to create an init and a mydeamon module in Python 2.7, under Debian 7

The init check the required things (db connection etc) and run mydaemon in a thread. mydeamon check db do things and write a logfile.

The problem when set the thread daemon the logging and function call fail. But if the thread not daemon working fine...

Can you help where I wrong or what will be a better approach.

init.py

import mydaemon, threading

print 'start'
t = threading.Thread( target = mydaemon.start, args = () )
t.daemon = True # error here
t.start()

mydaemon.py

import logging

def start():
   work()
   return

def work():
   logging.basicConfig( filename = 'mylog.log', level = logging.DEBUG )
   logging.info('foo log')
   print 'foo console' 
   return

Answer 1

Making it as a deamon means the background thread dies as soon as the main app closes. Your code 'works' as is, simply add a pause to init.py to model this behavior:

...
t.start()

import time
time.sleep(1)

This is discussed in more detail at http://pymotw.com/2/threading/#daemon-vs-non-daemon-threads.

The simply way to fix this is to join the thread.

import mydaemon, threading

print 'start'
t = threading.Thread( target = mydaemon.start, args = () )
t.daemon = True # error here
t.start()
t.join()

Answer 2

My collage found another method with external Daemon module (python-daemon)

http://www.gavinj.net/2012/06/building-python-daemon-process.html

In the tutorial have some error but read comments ;-)