memory leak: gtk.gdk.Pixbuf and gtk.gdk.GCX11 with gtkagg backend

Hi,

I'm looking for memory leaks in a python application and found leaks in
matplotlib. The application is graphic intensive. Each time it updates
the screen, matplotlib allocates another 5-10 megabytes memory for the
new gtk.gdk.Pixbuf and gtk.gdk.GCX11 while does not free up the buffers
allocated for the previous content.

I switched on garbage collection debugging with:

import gc
gc.enable()
gc.set_debug(gc.DEBUG_LEAK)

and tried to delete the leaking objects:

--- ./lib/matplotlib/backends/backend_gtkagg.py 2008-06-23
04:09:29.000000000 +0200 ++
+ /usr/lib/python2.4/site-packages/matplotlib-0.91.4-py2.4-linux-i686.egg/matplotlib/backends/backend_gtkagg.py
2008-10-02 00:05:32.000000000 +0200 @@ -3,6 +3,7 @@ """
from __future__ import division
import os
+import gc

import matplotlib
from matplotlib.figure import Figure
@@ -82,8 +83,17 @@
         h = int(ren.height)
         pixbuf = gtk.gdk.pixbuf_new_from_data(
             buf, gtk.gdk.COLORSPACE_RGB, True, 8, w, h, w*4)
- pixmap.draw_pixbuf(pixmap.new_gc(), pixbuf, 0, 0, 0, 0, w, h,
+ g = pixmap.new_gc()
+ pixmap.draw_pixbuf(g, pixbuf, 0, 0, 0, 0, w, h,
                            gtk.gdk.RGB_DITHER_NONE, 0, 0)

···

+
+ print "XXXXXXXXXX", pixbuf,
g,pixbuf.__grefcount__,g.__grefcount__
+ print gc.get_referrers(pixbuf)
+ print gc.get_referrers(g)
+ del pixbuf
+ del g
+ gc.collect()
+
         if DEBUG: print 'FigureCanvasGTKAgg.render_figure done'

     def blit(self, bbox=None):

The __grefcount__ values are 1 but the memory is not freed up even after
gc.collect().

Mátyás János wrote:

Hi,

I'm looking for memory leaks in a python application and found leaks in
matplotlib. The application is graphic intensive. Each time it updates
the screen, matplotlib allocates another 5-10 megabytes memory for the
new gtk.gdk.Pixbuf and gtk.gdk.GCX11 while does not free up the buffers
allocated for the previous content.

This sounds to me like a pygtk bug, not a matplotlib bug; a gtk object is hanging around after its reference has been deleted. What versions of gtk and pygtk are you using? This sounds dimly familiar. I don't know enough about gtk and pygtk to help, but I am sure the people who do know more will want to know the version.

Eric

···

I switched on garbage collection debugging with:

import gc
gc.enable()
gc.set_debug(gc.DEBUG_LEAK)

and tried to delete the leaking objects:

--- ./lib/matplotlib/backends/backend_gtkagg.py 2008-06-23
04:09:29.000000000 +0200 ++
+ /usr/lib/python2.4/site-packages/matplotlib-0.91.4-py2.4-linux-i686.egg/matplotlib/backends/backend_gtkagg.py
2008-10-02 00:05:32.000000000 +0200 @@ -3,6 +3,7 @@ """
from __future__ import division
import os
+import gc

import matplotlib
from matplotlib.figure import Figure
@@ -82,8 +83,17 @@
         h = int(ren.height)
         pixbuf = gtk.gdk.pixbuf_new_from_data(
             buf, gtk.gdk.COLORSPACE_RGB, True, 8, w, h, w*4)
- pixmap.draw_pixbuf(pixmap.new_gc(), pixbuf, 0, 0, 0, 0, w, h,
+ g = pixmap.new_gc()
+ pixmap.draw_pixbuf(g, pixbuf, 0, 0, 0, 0, w, h,
                            gtk.gdk.RGB_DITHER_NONE, 0, 0)
+
+ print "XXXXXXXXXX", pixbuf,
g,pixbuf.__grefcount__,g.__grefcount__
+ print gc.get_referrers(pixbuf)
+ print gc.get_referrers(g)
+ del pixbuf
+ del g
+ gc.collect()
+
         if DEBUG: print 'FigureCanvasGTKAgg.render_figure done'

     def blit(self, bbox=None):

The __grefcount__ values are 1 but the memory is not freed up even after
gc.collect().

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Agreed. I'm not sure how this bug could be resolved only on the matplotlib side. See if you can make a standalone (pygtk-only) example that demonstrates this bug and send it to their mailing list. Also, if it's possible, try updating pygtk. There was a very similar bug in an earlier version (sorry, I can't find the reference), that was resolved.

Cheers,
Mike

Eric Firing wrote:

···

M�ty�s J�nos wrote:
  

Hi,

I'm looking for memory leaks in a python application and found leaks in
matplotlib. The application is graphic intensive. Each time it updates
the screen, matplotlib allocates another 5-10 megabytes memory for the
new gtk.gdk.Pixbuf and gtk.gdk.GCX11 while does not free up the buffers
allocated for the previous content.

This sounds to me like a pygtk bug, not a matplotlib bug; a gtk object is hanging around after its reference has been deleted. What versions of gtk and pygtk are you using? This sounds dimly familiar. I don't know enough about gtk and pygtk to help, but I am sure the people who do know more will want to know the version.

Eric

I switched on garbage collection debugging with:

import gc
gc.enable()
gc.set_debug(gc.DEBUG_LEAK)

and tried to delete the leaking objects:

--- ./lib/matplotlib/backends/backend_gtkagg.py 2008-06-23
04:09:29.000000000 +0200 ++
+ /usr/lib/python2.4/site-packages/matplotlib-0.91.4-py2.4-linux-i686.egg/matplotlib/backends/backend_gtkagg.py
2008-10-02 00:05:32.000000000 +0200 @@ -3,6 +3,7 @@ """
from __future__ import division
import os
+import gc

import matplotlib
from matplotlib.figure import Figure
@@ -82,8 +83,17 @@
         h = int(ren.height)
         pixbuf = gtk.gdk.pixbuf_new_from_data(
             buf, gtk.gdk.COLORSPACE_RGB, True, 8, w, h, w*4)
- pixmap.draw_pixbuf(pixmap.new_gc(), pixbuf, 0, 0, 0, 0, w, h,
+ g = pixmap.new_gc()
+ pixmap.draw_pixbuf(g, pixbuf, 0, 0, 0, 0, w, h,
                            gtk.gdk.RGB_DITHER_NONE, 0, 0)
+
+ print "XXXXXXXXXX", pixbuf,
g,pixbuf.__grefcount__,g.__grefcount__
+ print gc.get_referrers(pixbuf)
+ print gc.get_referrers(g)
+ del pixbuf
+ del g
+ gc.collect()
+
         if DEBUG: print 'FigureCanvasGTKAgg.render_figure done'

     def blit(self, bbox=None):

The __grefcount__ values are 1 but the memory is not freed up even after
gc.collect().

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Matplotlib-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
    
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Grand prize is a trip for two to an Open Source event anywhere in the world
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--
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

Hi,

thank you very much! The memory leak disappeared after I updated
pygobject from 2.12 to 2.13.2.