Re: [Matplotlib-users] Qt4/PySide memory leak

[Christoph G. <cg...@uc...>]

On 9/24/2012 3:32 PM, David Honcik wrote:
> I've run into a large memory leak using Matplotlib with PySide and the
> Qt4 back end.  I'm using :
> Python 3.2
> Numpy 1.6.2
> Pyside 1.1.1 (qt474)
> Matplotlib 1.2 (first the Capetown Group port to Python 3, then 1.2 RC2)
> on Windows XP 32 bit
> I've tried using the Python 2.7 branch of all of the above and don't see
> the problem.  I don't see the problem with the Tk back end.  I don't see
> the problem with the Qt4 back end and PyQt4.  Only with the above
> mentioned versions and using the Qt4 back end with PySide.
> The following script will reproduce the problem :
> --------------------
> import matplotlib
> matplotlib.use('Qt4Agg')
> matplotlib.rcParams['backend.qt4']='PySide'
> import pylab
> arrayX = []
> arrayY = []
> for nIndex in range(0, 100):
> arrayX.append(nIndex)
> arrayY.append(nIndex)
> Figure = matplotlib.pyplot.figure(1)
> Axes = Figure.add_axes([ 0.05, 0.05, 0.95, 0.95])
> Axes.plot(arrayX,
> arrayY,
> color      = "blue",
> marker     = "o",
>            markersize = 5.0)
> Axes.set_xlim(arrayX[0], arrayX[len(arrayX) - 1])
> Axes.set_ylim(arrayY[0], arrayY[len(arrayY) - 1])
> matplotlib.pyplot.show()
> --------------------
> I run the above, grab the lower right sizing handle on the plot window
> and start resizing the window.  Watching the python process in task
> manager, each resize leaks a noticeable amount of memory.  A few minutes
> of this will get process memory up to ~2.5 GB. At that point it crashes.
> I'm new here, am I in the right place?
>

I can reproduce this exactly, also with pyside 1.1.2 and an empty plot. 
Looks like QtGui.QImage is leaking.

import matplotlib
matplotlib.use('Qt4Agg')
matplotlib.rcParams['backend.qt4']='PySide'
from matplotlib import pyplot
pyplot.plot()
pyplot.show()

--
Christoph