[Matplotlib-users] Re: memory leaks, 0.54.1 with .2a modifications

[Eric F. <ef...@km...>]

Steve,

>There does seem to be a memory problem when using Python and GTK+. Have
>you seen the pygtk FAQ 8.4 "Is there a resource leak? Why do I run out
>of memory using Pixbuf?"
>
>  
>

Yes, I saw that, tried putting in explicit gc.collect() calls, but it 
didn't help.  I concluded the problem was different.  I also looked at 
the draw function in backend_gtk.py.  What I don't understand is how and 
when the no-longer-used gtk objects (pixmap, etc) really can and should 
be de-allocated.  Evidently they persist when the python reference to 
them goes out of scope.

Thanks for your changes.

Eric

>>From looking at matplotlib/backends/backend_gtk.py I noticed every
>FigureCanvasGTK.draw() operation allocates memory for a new pixmap and a
>new graphics context. So looping 200 times in your first test script
>allocates memory for 200 pixmaps and 200 graphics contexts, yet the
>pixmap size has not changed and the graphics context has not changed. I
>think it would be more memory efficient to create a pixmap and continue
>using it until a larger pixmap is required. The graphics context does
>not change its default settings, so it does little, but is required for
>the GDK calls, again it looks to me like it would be better to create
>one and reuse it.
>
>Here are some changes I made to matplotlib/backends/backend_gtk.py I
>estimate saves around 10% of the memory leak.
>However I can't check that it plots correctly properly because I
>currently get a plot of a black rectangle in GTK mode (GTKAgg works OK),
>which I think was mentioned as a numarray problem with the latest
>matplotlib release.
>
>FigureCanvasGTK.__init__(self,figure):  # add the following line
>        self.pixmap_width, self.pixmap_height = -1, -1 # new
>
>  
>
FigureCanvasGTK.draw(self): # replace with this:

>    def draw(self):
>        if not self._doplot: return
>        drawable = self.window        
>        if drawable is None: return
>  
>
>        
>        width = int(self.figure.bbox.width())
>        height = int(self.figure.bbox.height())
>
>        if width > self.pixmap_width or height > self.pixmap_height:
>            self._gpixmap = gtk.gdk.Pixmap(drawable, width, height)
>            self.pixmap_width  = width
>            self.pixmap_height = height
>
>        self.figure.draw( RendererGTK(self, self._gpixmap,
>self.figure.dpi) )
>        drawable.draw_drawable(self._ggc, self._gpixmap, 0, 0, 0, 0,
>width, height)
>
>FigureCanvasGTK.realize(self, widget): # add the following line:
>        self._ggc = self.window.new_gc()
>
>Regards
>Steve
>
>
>  
>