[mod_python] global var on 2.7

ok, thanks for those advices and insight into mod_python. I'll do more
testing with the caching module it looks like a solution to my current
problem.

it's not trusly enormous but the loading makes the difference between
an instantaneous page and a one second delay.

I'm forwarding your answer to the mailing list for the future
generations ;) (or at least the ones stuck with apache1.3 :)

On 7/10/05, Jorey Bump <list at joreybump.com> wrote:
> antoine wrote:
> > hum, ok but I tried a few more time to access this page in different
> > fashions and I can say in some circonstances the processes are being
> > reused (and therefore my bigdict object is not reloaded, as expected)
> > so it is consistent with Graham explanations.
> 
> I may have misinterpreted your statement to mean that you would
> eventually begin using the object in a persistent manner, rather than
> occassionally access it, which is the case and consistent with both of
> our explanations.
> 
> > The cached module "trick"  should be more performant that the "global"
> > only if the modules are cached once for all the processes (and nor per
> > process) I guess? Anyway, I'll try and see for myself.
> 
> Well, they are cached per child, so you get a boost.
> 
> > Should this module also use global or not? Is a simple implementation like:
> 
> I wouldn't.
> 
> > CacheBigdic.py
> > def getBigDic():
> >   return looong_and_painful_process()
> >
> > enough or should I go for :
> > CacheBigdic.py
> > bigdic = None
> > def getBigDic():
> >   global bigdic
> >   if not bigdic:
> >     return looong_and_painful_process()
> >   else:
> >     return bigdic
> >
> > and call this from index.py with
> >
> > import CacheBigdic
> > bigdic = CacheBigdic.getBigdic()
> > def index(req):
> >   ...
> >   use(bigdic)
> >   ...
> 
> I'd do this, probably:
> 
> # CacheBigdic.py
> 
> bigdic = looong_and_painful_process()
> 
> # publishedmodulewithuniquename.py
> 
> import CacheBigdic
> def index(req):
>     ...
>     use(CacheBigdic.bigdic)
>     ...
> 
> If you find errors appearing in your apache log under heavy load, you
> may need to alter CacheBigdic.py:
> 
> try:
>     bigdic = looong_and_painful_process()
> except TheErrorYouSee:
>     bigdic = looong_and_painful_process()
> 
> It looks redundant, but it's needed because the module is cached. In any
> case, it's important to protect yourself if your bigdic gets you in trouble.
> 
> > I do not need truly global var, the cached object is never modified
> > (and the long_and_painful_process() is already nothing but a (c)pickle
> > ;).
> 
> Then this should work, but be aware that if your bigdic is truly
> enormous, you should tuck it away and only use it when needed. Excessive
> handling of bigdic could result in a huge load and bring your system to
> exhaustion.
> 
> A database is a good candidate for this.
> 


-- 
Antoine
http://delaunay.org/antoine