[mod_python] mod_python executing old versions of my code

Graham Dumpleton grahamd at dscpl.com.au
Tue Jan 24 18:49:40 EST 2006

=?ISO-8859-2?Q?Martin_MOKREJ=A9?= wrote ..
> Graham Dumpleton wrote:
> >>But I can find no way to force testmodule to be re-imported. What am
> I
> >>doing wrong?
> > 
> > 
> > You are not doing anything wrong, the current system simply doesn't
> > work very well.
> > 
> > The best you can get is to use:
> > 
> >   from mod_python import apache
> >   import os
> > 
> >   __here__ = os.path.dirname(__file__)
> >   
> >   def handler(req):
> >        req.write("Hello World!")
> >        testmodule = apache.import_module("testmodule,path=[__here__])
> >        testmodule.foo(req)
> >        return apache.OK
> > 
> > This uses apache.import_module() on each request to import the module.
> > In practice though, if the file has not changed it just uses what is
> already
> > in the cache. If it has changed, you should then see the change.
> > 
> > You can't use apache.import_module() at global scope in the module and
> > get the same effect as that only gets executed when main.py is imported.
> > Thus you don't get the check for changes to testmodule.py on every
> > request.
> > 
> > I have a completely rewritten module importing system for mod_python
> > which addresses nearly all the issues it has. I will be making it available
> for
> > trialing after mod_python 3.2.6 is officially released. It will require
> though
> > having 3.2.6, which means it will be useless to you with 2.7.11.
> I still see problems with module import using 3.2.6 on linux, compiled
> today.
> I am using typically something like:
> try:
>     from mod_python import apache
>     _directory = os.path.dirname(__file__)
>     for _my_modulename in ['web_settings', 'web_header', 'web_menu', 'web_text_frame',
> 'web_footer', 'sql_io', 'helper_functions', 'globals']:
>         __dict__[_my_modulename] = apache.import_module(_my_modulename,
> log=1, path=[_directory])
> except: # without raise
>     import web_settings
>     import web_header
>     import web_menu
>     import web_text_frame # calls mysql_python driver
>     import web_footer
>     import sql_io
>     import helper_functions
>     import iresite_globals
> So, should I wait or adjust my code?

What sort of problems?

Note though that the more major problems with apache.import_module()
aren't fixed in 3.2.6.

You should find that mod_python.publisher may work a bit better in 3.2.6
as it uses a separate module importer. If you use apache.import_module()
inside of mod_python.publisher code, you could end up with a whole new
bunch of problems if a module is imported by both mod_python.publisher
and apache.import_module(). Specifically that there will be two distinct
copies of the module. I pointed out the problems that the changes to the
mod_python.publisher module importer would cause in this situation, but
the changes were still made. I would have preferred to have seen the use
of apache.import_module() by mod_python.publisher be left alone until
apache.import_module() was fixed. Ie., better known problems than a whole
class of new ones. :-(

> > Whether this new module importing system gets adopted is another
> > matter entirely though. Some have argued in the past that the current
> > arrangement is adequate even though it has known problems. ;-(
> No, the apache stop/start sucks, the restart approach doesn't work as the
> init.d scripts on gentoo
> fail to wait for apache to shutdown completely ... they start to startup
> somehow immediately,
> recognize apache is still up, die but leave the lockfiles in. I have to
> start apache in
> several start/start attempts to get it started actually.

Apache child processes not terminating promptly may be because of:


this is not addressed in 3.2.6 anf needs a bit more research first to see
if the simple solution will not cause other issues. At this stage the only
known issue is that not calling Py_Finalize() will mean that code registered
using Python wrapper for atexit() will not be called. Have to check properly
yet though whether code registered with apache.register_cleanup() and
req.server.register_cleanup() will still be executed.


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