Matplotlib Figures not cleaned up during loop

It seems like while generating plots in a loop, the memory grows over time when running the script in spyder.

I have a funny use-case where I’m making a lot of large plots, and then when I’m done I like to interactively look at the last plot that was generated.

To reproduce using this little script:

import sys
import gc
import numpy as np
import matplotlib
matplotlib.use('Qt4Agg')
import matplotlib.pyplot as plt

arr = np.random.rand(10000, 10000)

def memplot_plot(arr):
    plt.matshow(arr)    
    plt.close()

print '*' * 80
for i in range(1, 10):
    print 'i : ' + str(i)    
    print  len( gc.get_objects())
    print sys.getsizeof(gc.get_objects())
    memplot_plot(arr)    
    gc.collect()
print '*' * 80

From the command-line

*****************************************
i : 1
61424
514568
i : 2
61710
514568
i : 3
61713
514568
i : 4
61716
514568
i : 5
61719
514568
i : 6
61722
514568
i : 7
61725
514568
i : 8
61728
514568
i : 9
61731
514568
*****************************************

From spyder, running in a dedicated terminal with interaction afterwards

********************************************************************************
i : 1
64416
578936
i : 2
67685
578936
i : 3
70737
578936
i : 4
73789
651352
i : 5
76841
651352
i : 6
79893
651352
i : 7
82945
732816
i : 8
85997
732816
i : 9
89049
732816
********************************************************************************

And for fun, my windows task manager. The four small blips are four runs from the commandline (python, python -i, ipython and ipython -i). The last one is from Spyder. And this is not clean because I’m also working in the background.

matplotlib.get_backend()
Out[2]: u'Qt4Agg'

matplotlib.__version__
Out[3]: '1.4.3'

Let me know if you need any more information. Same behavior was observed on a colleague’s machine.

[goanpeca]

So, should we close?

[ccordoba12]

This is very old, let’s close it.