proper way to clean up a python service -- atexit, signal, try/finally

The atexit module defines functions to register and unregister cleanup functions. Functions thus registered are automatically executed upon normal interpreter termination. atexit runs these functions in the reverse order in which they were registered; if you register A, B, and C, at interpreter termination time they will be run in the order C, B, A.,At normal program termination (for instance, if sys.exit() is called or the main module’s execution completes), all functions registered are called in last in, first out order. The assumption is that lower level modules will normally be imported before higher level modules and thus must be cleaned up later.,Register func as a function to be executed at termination. Any optional arguments that are to be passed to func must be passed as arguments to register(). It is possible to register the same function and arguments more than once.,Note: The functions registered via this module are not called when the program is killed by a signal not handled by Python, when a Python fatal internal error is detected, or when os._exit() is called.

try:
with open('counterfile') as infile:
   _count = int(infile.read())
except FileNotFoundError:
   _count = 0

def incrcounter(n):
   global _count
_count = _count + n

def savecounter():
   with open('counterfile', 'w') as outfile:
   outfile.write('%d' % _count)

import atexit

atexit.register(savecounter)

def goodbye(name, adjective):
   print('Goodbye %s, it was %s to meet you.' % (name, adjective))

import atexit

atexit.register(goodbye, 'Donny', 'nice')
# or:
   atexit.register(goodbye, adjective = 'nice', name = 'Donny')

import atexit

@atexit.register
def goodbye():
   print('You are now leaving the Python sector.')

This module provides access to some variables used or maintained by the interpreter and to functions that interact strongly with the interpreter. It is always available.,Clear the internal type cache. The type cache is used to speed up attribute and method lookups. Use the function only to drop unnecessary references during reference leak debugging.,If exc_clear() is called, this function will return three None values until either another exception is raised in the current thread or the execution stack returns to a frame where another exception is being handled.,Return a dictionary mapping each thread’s identifier to the topmost stack frame currently active in that thread at the time the function is called. Note that functions in the traceback module can build the call stack given such a frame.

>>>
import sys
   >>>
   sys.float_info.dig
15
   >>>
   s = '3.14159265358979'
# decimal string with 15 significant digits
   >>>
   format(float(s), '.15g') # convert to float and back - > same value '3.14159265358979'

>>> s = '9876543211234567'
# 16 significant digits is too many!
   >>>
   format(float(s), '.16g') # conversion changes value '9876543211234568'

if sys.hexversion >= 0x010502F0:
   # use some advanced feature
   ...
   else:
      # use an alternative implementation or warn the user
      ...

if sys.platform.startswith('freebsd'):
   # FreeBSD - specific code here...
   elif sys.platform.startswith('linux'):
   # Linux - specific code here...