ffc team mailing list archive

[Johan Hake <johan.hake@xxxxxxxxx>]

I am probably the athor of this code.

The intention was (if I remember correctly) to prevent memory leak of unused 
forms. I cannot remember why I chose refcount of 6, maybe that is too high. 
That _memory_check gets stuck at 10 seems to be a bug. Just remove the else 
clause so it get increased each time a form gets inserted in the cache.

I can check the logic behind the refcount of 6.

Johan

On Tuesday February 1 2011 03:58:50 Anders Logg wrote:
> On Tue, Feb 01, 2011 at 09:30:18AM -0000, Mikael Mortensen wrote:
> > Public bug reported:
> > 
> > The _memory_check in ffc/jitcompiler.py gets stuck at 10. In the code
> > 
> > else:
> >         preprocessed_form = preprocess(form, common_cell=common_cell)
> >         _memory_cache[(id(form), repr(form))] = preprocessed_form
> >         
> >         # For each 10th time the refcount of the cached form are checked
> >         # and superflous forms are poped
> >         
> >         if (_memory_check % 10) == 0:
> >             for key, cached_form in _memory_cache.items():
> >                 if sys.getrefcount(cached_form) < 6:
> >                     _memory_cache.pop(key)
> >         
> >         else:
> >             _memory_check += 1
> > 
> > if (_memory_check % 10) == 0 is True, then it doesn't add 1 and remains
> > stuck at 10 meaning that it will check the whole _memory_cache on every
> > new form.
> > 
> > This particular piece of code is also responsible for some more
> > headache. In my code I set up a large numer of forms (perhaps > 20) and
> > solve my equations. No problems. I then decide to make some changes
> > (perhaps to a model constant), which requires that I also redefine all
> > my forms. When I continue with my iterations the refcount seams to be
> > less than 6 and my new form always gets popped and iterations slows down
> > because of the repeated Form call in assemble that never gets use of
> > _memory_cache. Anyway, I hacked it for my equationset simply by using a
> > larger value than 10 in the _memory_check above. Perhaps this should be
> > a parameter?
> > 
> > ** Affects: ffc
> > 
> >      Importance: Undecided
> >      
> >          Status: New
> 
> I'm not sure why we need to limit the memory cache at all. I don't
> remember adding this particular code. Who added it?
> 
> --
> Anders
> 
> _______________________________________________
> Mailing list: https://launchpad.net/~ffc
> Post to     : ffc@xxxxxxxxxxxxxxxxxxx
> Unsubscribe : https://launchpad.net/~ffc
> More help   : https://help.launchpad.net/ListHelp