Memory Leak when add mesh to scene

[pebertli]

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Checklist

• [X] I have searched for similar issues.
• [X] For Python issues, I have tested with the latest development wheel.
• [X] I have checked the release documentation and the latest documentation (for master branch).

Describe the issue

The memory usage constantly increases when a add a model, clear geometry, and re-add a new model to the OffscreenRenderer scene. Even if I recreate the OffscreenRenderer instance at each iteration, at a certain point, the memory leak starts again I appreciate any help.

Steps to reproduce the bug

import open3d as o3d
import csv


# main entry point
def main():
      
    input_files = read_list_gltf('./list.csv')

    render = o3d.visualization.rendering.OffscreenRenderer(512, 512)
    render.scene.set_background([0.1, 0.2, 0.3, 1.0])  # RGBA
    render.scene.show_axes(True)
    vertical_field_of_view = 15.0  # between 5 and 90 degrees
    aspect_ratio = 1  # azimuth over elevation
    near_plane = 0.1
    far_plane = 50.0
    fov_type = o3d.visualization.rendering.Camera.FovType.Vertical
    render.scene.camera.set_projection(vertical_field_of_view, aspect_ratio, near_plane, far_plane, fov_type)

    # Look at the origin from the front (along the -Z direction, into the screen), with Y as Up.
    center = [0, 0, 0]  # look_at target
    eye = [0, 0, 10]  # camera position
    up = [0, 1, 0]  # camera orientation
    render.scene.camera.look_at(center, eye, up)

    for model_index, file in enumerate(input_files):

        model = o3d.io.read_triangle_model(file)
        render.scene.add_model(f'model', model)

        # render to image code
        # ....

        # clear scene
        render.scene.clear_geometry()
        model = None

Error message

No response

Expected behavior

The update of the scene should not cause a memory leak.

Open3D, Python and System information

- Operating system: Windows 11 64-bit
- Python version: 3.9.7 (tags/v3.9.7:1016ef3, Aug 30 2021, 20:19:38) [MSC v.1929 64 bit (AMD64)]
- Open3D version: 0.15.1
- System architecture: x86
- Is this a remote workstation?: no
- How did you install Open3D?: pip
- Compiler version (if built from source): NA

Additional information

Memory usage after a few seconds