Apache Django Mod_Wsgi - auto reload

Question

I am trying to auto reload my django app which uses apache + mod_wsgi on my local windows machine.

I'd like to know where do I add this code that's referenced in the following article:

http://code.google.com/p/modwsgi/wiki/ReloadingSourceCode

def _restart(path):
    _queue.put(True)
    prefix = 'monitor (pid=%d):' % os.getpid()
    print >> sys.stderr, '%s Change detected to \'%s\'.' % (prefix, path)
    print >> sys.stderr, '%s Triggering Apache restart.' % prefix
    import ctypes
    ctypes.windll.libhttpd.ap_signal_parent(1)

Answer 1

Read:

http://blog.dscpl.com.au/2008/12/using-modwsgi-when-developing-django.html

It tells you exactly where to place the file when using Django. You just need to make the code change that everyone is pointing out to you in the source code reloading documentation section related to Windows. Also read:

http://blog.dscpl.com.au/2009/02/source-code-reloading-with-modwsgi-on.html

which explains the variations on the first related to Windows.

Answer 2

You replace the restart function that is mentioned in the block of code above in the same article.

Answer 3

You replace the restart function in the following block of code you find on the page:

Monitoring For Code Changes

The use of signals to restart a daemon process could also be employed in a mechanism which automatically detects changes to any Python modules or dependent files. This could be achieved by creating a thread at startup which periodically looks to see if file timestamps have changed and trigger a restart if they have.

Example code for such an automatic restart mechanism which is compatible with how mod_wsgi works is shown below.

import os
import sys
import time
import signal
import threading
import atexit
import Queue

_interval = 1.0
_times = {}
_files = []

_running = False
_queue = Queue.Queue()
_lock = threading.Lock()

def _restart(path):
    _queue.put(True)
    prefix = 'monitor (pid=%d):' % os.getpid()
    print >> sys.stderr, '%s Change detected to \'%s\'.' % (prefix, path)
    print >> sys.stderr, '%s Triggering process restart.' % prefix
    os.kill(os.getpid(), signal.SIGINT)

Answer 4

I use this code on my server

touch site.wsgi

and it work. After reload page in browser I get page with changes. May be it ugly - but simple and no necessary restart apache.

Answer 5

I test this with Bitnami DjangoStack http://bitnami.org/stack/djangostack and Windows XP installed on D:\BitNami DjangoStack and C:\Documents and Settings\tsurahman\BitNami DjangoStack projects\myproject as project directory (default install)

as in http://code.google.com/p/modwsgi/wiki/ReloadingSourceCode#Restarting_Apache_Processes, I added

MaxRequestsPerChild 1

in file D:\BitNami DjangoStack\apps\django\conf\django.conf see comment by Graham Dumpleton

then I created a file monitor.py in my project directory with content as in http://code.google.com/p/modwsgi/wiki/ReloadingSourceCode#Monitoring_For_Code_Changes and replace the _restart method with http://code.google.com/p/modwsgi/wiki/ReloadingSourceCode#Restarting_Windows_Apache, here is the part of the script

....

_running = False
_queue = Queue.Queue()
_lock = threading.Lock()

def _restart(path):
    _queue.put(True)
    prefix = 'monitor (pid=%d):' % os.getpid()
    print >> sys.stderr, '%s Change detected to \'%s\'.' % (prefix, path)
    print >> sys.stderr, '%s Triggering Apache restart.' % prefix
    import ctypes
    ctypes.windll.libhttpd.ap_signal_parent(1)

def _modified(path):
    try:

....

and in file D:\BitNami DjangoStack\apps\django\scripts\django.wsgi,

....

import django.core.handlers.wsgi

import monitor
monitor.start(interval=1.0)
monitor.track(os.path.join(os.path.dirname(__file__), 'site.cf'))

application = django.core.handlers.wsgi.WSGIHandler()

and then restart the Apache server