Giove's profile - activity

If I run the following code:

import gc

while True:
    P = Polyhedron([[1,0,0,0], [0,1,0,0], [0,0,1,0], [0,0,0,1]])
    faces = P.faces(3)
    del P, faces
    print "memory usage: " + str(get_memory_usage()) + ", gc: " + str(gc.collect())

the memory usage keeps increasing. Do you know what is the cause and how to avoid this problem?