[mod_python] Caching issues

Apologies for more trouble on the caching issue-- I've been adapting
some of my scripts over to this apache.load_module function, but I
don't think I'm seeing resolution to the issue.  If I've read the
documentation properly, it seems that the PythonOption for
auto-reloading is set to On by default, so to be clear, I haven't put
a line for that in my httpd.conf file.  Are there any other tricks, or
have I simply misread the documentation?  I still have to restart the
Apache service in order to push the changes.

Tim

On Sun, Jan 11, 2009 at 2:32 PM, Tim Valenta <tonightslastsong at gmail.com> wrote:
> Despite the jab at Windows, the site will be deployed on a Unix
> machine.  I just prefer Windows for ease of use, especially since my
> wife has zero experience on a unix terminal or in the dearth of truly
> professional software found on the Unix/Linux platform.  So yes, in
> the end it will be on a "real" operating system,  But for now I'm
> willingly sticking to a more user-friendly environment for the simple
> folk.
>
> Given the characteristics of PHP that allow it to circumvent this
> caching stuff, I still think a nice little friendly red-flag reminder
> on the main mod_python tutorial should point out this limitation of an
> Apache module like this, for those of us like me, who would have gone
> many months more before having every accidentally found this manual
> import method.
>
> On Sun, Jan 11, 2009 at 2:23 PM, Graham Dumpleton
> <graham.dumpleton at gmail.com> wrote:
>>
>> 2009/1/12 Tim Valenta <tonightslastsong at gmail.com>:
>> >> Still not short enough, so much so I stopped part way through.
>> >
>> > And for that I apologize.  I do appreciate the straight answer given,
>> > though I would appreciate much more the addition of that fact in some
>> > point-blank documentation that was easy to find.  I have scoured the
>> > mod_python archives by search engine and came out utterly empty
>> > handed.  I knew what the problem was, but I could find nothing to
>> > remedy the issue.  I haven't encountered anything quite like this in
>> > my adventures with PHP, perl, or other similar scripting languages
>> > piloted by Apache.  It raises a valid concern to which I ideally
>> > should have found answers very quickly.
>> >
>> > I hope this cures the subsequent issue given in the latter half of my message.
>>
>> PHP is specifically designed for web applications and it purposely
>> throws away all code at the end of each request and thus is reloading
>> it all on every request. Have a read of:
>>
>>  http://blog.ianbicking.org/2008/01/12/what-php-deployment-gets-right/
>>
>> I would be very surprised if mod_perl auto reloaded code as it is
>> similar to Python in that you are applying a non web language to the
>> web. Only way perl code would be reload is if you were running them as
>> CGI scripts. If you run Python as CGI scripts you will get reloading
>> as well, but as with anything CGI, much slower.
>>
>> BTW, maybe read:
>>
>>  http://blog.dscpl.com.au/2008/12/using-modwsgi-when-developing-django.html
>>
>> For WSGI hosted Python web application, this provides auto reloading
>> on code changes. You do need to use a real operating system though,
>> and not Windows.
>>
>> Graham
>>
>> > Tim
>> >
>> > On Sat, Jan 10, 2009 at 10:23 PM, Graham Dumpleton
>> > <graham.dumpleton at gmail.com> wrote:
>> >>
>> >> 2009/1/11 Tim Valenta <tonightslastsong at gmail.com>:
>> >> > Hello all-- I've been experiencing a caching issue from the
>> >> > very beginning of my use of mod_python...  It's been at least 2 months now,
>> >> > and I keep running into actual issues that prevent me from coding.
>> >> > I have a knack for over-explaining, so I'll try to keep this concise yet
>> >> > descriptive.
>> >>
>> >> Still not short enough, so much so I stopped part way through.
>> >>
>> >> The simple matter of it is that mod_python does not do deep checking
>> >> of code for changes, nor does it automatically restart the process
>> >> when code is changed. Thus the need to restart Apache when you make
>> >> code changes to anything imported from sys.path is expected and normal
>> >> behaviour.
>> >>
>> >> The only time any code is automatically reloaded is the direct code
>> >> files imported by mod_python using its own special module importer.
>> >> This is documented under 'import_module()' function in:
>> >>
>> >>  http://www.modpython.org/live/current/doc-html/pyapi-apmeth.html
>> >>
>> >> Graham
>> >>
>> >> > I'm developing a site on my local machine, Windows Vista, using Apache 2.2.x
>> >> > and mod_python 3.3.1 .  I'm a programmer for a living, and I'm not quick to
>> >> > point the finger at the language, *but* (you knew that was coming, eh?) I
>> >> > know my code isn't to blame for the issue:
>> >> > I write some basic code for an 'index.py' file, using the
>> >> > mod_python.publisher handler.  'index.py' includes other modules which I've
>> >> > coded from that same location, etc, etc.  Nothing fancy.  Any changes I make
>> >> > in the 'index.py' file will be reflected immediately on my local web server.
>> >> >  On the other hand, any changes I make to the modules included via import
>> >> > from within 'index.py' are completely ignored by the web server.  It took me
>> >> > a while to realize that my pages didn't reflect my code.  I also discovered
>> >> > that the .pyc files had nothing to do with it.  I finally just restarted the
>> >> > apache web service (which in fact runs as a service on my machine), and then
>> >> > my code finally gets pushed through to the web server.
>> >> > I've been looking around practically every other day for documentation on
>> >> > how to make apache/mod_python simply cut it out and stop caching my python
>> >> > code, but I've found nothing.  You can imagine the annoyance this presents,
>> >> > since I have to restart my web server every single time I make even the
>> >> > slightest change to a 'utility.py' file, etc.
>> >> > I've been coping with the problem for a while now, but then I've found far
>> >> > more annoying issues recently.  To abbreviate the problem into short terms,
>> >> > I've got a main module 'MAIN' which imports another module for a class
>> >> > 'CLASS'.  CLASS also has a few imports, such as 'backend' stuff for
>> >> > interfacing with various databases, etc.  We'll call the 'backend' module
>> >> > "BACKEND".  Given the setup, any changes I make to CLASS or BACKEND require
>> >> > an apache restart in order to take effect.
>> >> > I have a function in CLASS which calls a function from it's imported BACKEND
>> >> > module.  I tried adding a parameter to the BACKEND function in question, and
>> >> > properly passed said parameter while in CLASS, yet the mod_python debugger
>> >> > spits out an error about me having passed 3 arguments, when the BACKEND
>> >> > function takes exactly 2.  This is outright false, since my function in
>> >> > BACKEND looks like:
>> >> > def getUsers(self, req, terms):
>> >> >
>> >> > and I'm calling it with
>> >> > self.backend.getUsers(self.req, search)
>> >> >
>> >> > In reality, my code dictates that I'm passing 3 (including the implicit
>> >> > 'self' argument), and BACKEND's 'getUsers' does in fact take exactly 3
>> >> > arguments.  Yet, the debugger is telling me that it takes only 2.
>> >> > I was trying to pass it 'req' because I wanted to investigate a little error
>> >> > in the code by printing something to the output HTML.  So, my attempt is
>> >> > foiled, since somewhere something isn't being updated to what my most
>> >> > current code actually says.
>> >> > Just to test, I made the 'getUsers' function return immediately with a
>> >> > string of gibberish, like 'return "adsfasdfadsfa"'.  this should make my
>> >> > other code spin wildly out of control and encounter errors, yet when I
>> >> > restart apache and test it... lo and behold, it's completely ignoring my
>> >> > goofy 'return' statement.  The 'getUsers' function is still somehow
>> >> > returning valid data, as if the 'return' wasn't there at all!
>> >> > So then I tried causing actual syntax errors.  The debugger caught this,
>> >> > much to my inner joy.  So I tried causing a semantic error instead:
>> >> > referencing a non-existent attribute of a non-existent variable:
>> >> > madeUpVar.moo = 42
>> >> > Syntactically, nothing wrong, but at run time it should most definitely
>> >> > encounter a NameError or something equally as realistic.  But I restart
>> >> > apache, and... nothing.  The line is completely ignored.
>> >> > Which leads me to believe that it's not actually being 'ignored' per se, but
>> >> > rather the code being compiled is not the same as the code in play within
>> >> > the web server.  When I delete my .pyc files and restart apache and visit
>> >> > the URL that triggers my python code, my .py files are in fact being
>> >> > recompiled down to their byte code .pyc files.  And clearly the interpreter
>> >> > is processing my code, since it flags me on improper syntax.  Yet, no matter
>> >> > what kind of syntactically-sound nonsense I put into my code, the changes
>> >> > aren't being reflected in my web server.
>> >> > These problems come and go, and I've go better explanation than over zealous
>> >> > caching.  I imagine that by tomorrow sometime when I start my computer up,
>> >> > the problem will have disappeared for the time being.
>> >> > I've cursed this computer up and down as I've tried to figure out ANYTHING
>> >> > that I can do to alleviate the issue, by to no avail.
>> >> > Anybody with counsel to spare my tired brain is welcome to share...
>> >> > _______________________________________________
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>> >> > Mod_python at modpython.org
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>> >> >
>> >> >
>> >
>
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