I guess you're right... I misunderstood the result of gc.collect() as the number of objects that could not be freed. The good news is that after fixing the bug I was looking at, there are no more objects that cannot be freed (gc.garbage is empty).
Thanks! --Michiel. --- On Sun, 11/8/09, Eric Firing <efir...@hawaii.edu> wrote: > From: Eric Firing <efir...@hawaii.edu> > Subject: Re: [matplotlib-devel] Circular references in Figure > To: "Michiel de Hoon" <mjldeh...@yahoo.com> > Cc: matplotlib-devel@lists.sourceforge.net > Date: Sunday, November 8, 2009, 1:43 AM > Michiel de Hoon wrote: > > Hi everybody, > > > > I was looking at this bug about a memory leak: > > > > https://sourceforge.net/tracker/?func=detail&atid=560720&aid=2889570&group_id=80706 > > > > While this bug is now essentially fixed, I noticed > that the Figure class contains some circular references that > prevent it from being cleaned up by the garbage collector, > which is effectively a memory leak. At least, for this > code: > > > >>>> from matplotlib.figure import Figure > >>>> fig = Figure() > >>>> del fig > > > > the garbage collector reports 76 unreachable objects. > This seems to be independent of which backend is being > used. > > > > Is it worthwhile to look deeper into it? Or should we > accept that it is unavoidable that a library of the size of > matplotlib will have circular references? > > > > The purpose of the garbage collector is to handle the case > of circular references--and mpl is full of circular > references. When there are no circular references, > then reference counting suffices. The garbage > collector fails to handle circular references when an object > has a __del__ method. I don't think we have that > problem. > > I am not actually seeing the result you describe, > though. Using python from the interactive prompt--no > ipython--when I do gc.collect() and then gc.get_count() I > get back to the count from before instantiating the Figure. > > >>> gc.get_count() > (4, 0, 0) > >>> gc.get_count() > (5, 0, 0) > >>> gc.get_count() > (5, 0, 0) > >>> gc.get_count() > (5, 0, 0) > >>> fig = Figure() > >>> gc.get_count() > (128, 0, 0) > >>> del(fig) > >>> gc.get_count() > (128, 0, 0) > >>> gc.collect() > 76 > >>> gc.get_count() > (4, 0, 0) > >>> gc.get_count() > (5, 0, 0) > > Eric > > > > > --Michiel. > > > ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
