Memory Leak in netgen.csg Module

[TBeKL]

When working with objects of the netgen.csg module, the memory reserved for the Python process increases continuously. It is possible that the reserved memory is not released or only partially released when objects are destroyed. The following minimal example illustrates the problem.

from netgen.csg import Pnt, Plane, Vec

args = (Pnt(0, 0, 0), Vec(1, 0, 0))

for i in range(1000000):
    Plane(*args)

The figure in the appendix shows the reserved memory over runtime captured by memory profiler 0.61.0. The memory increases continuously and is only released when the process ends.
As I use NGSolve to compute time-dynamic systems with complex geometries and create many of these objects repeatedly, this is a very severe limitation.
I’m using Python 3.7.9 with NGSolve 6.2.2102.