Blender consuming all memory

Question

I have hundreds of thousands of models in a folder. In my script I have a loop which loads each model at a time as object in my scene then render an image of it then delete the object. After couple of thousands models, blender consumed all my machine memory and then froze and stopped processing. Do I have to load the startup file every time before loading and processing each of the models to prevent this from happening? Or do I use the garbage collector? I'm not sure how I can avoid this from happening?

Answer 1

I was able to avoid this by saving my file as a startup file then reloading the startup .blend to clean up all the data blocks.

Answer 2

First remove the meshes/objects with the following code:

for obj in bpy.context.scene.objects:
     if obj.type == 'MESH':
         obj.select = True
     else:
         obj.select = False
 bpy.ops.object.delete()

where you can check type against any of the following values according to [this documentation][1]:

[‘MESH’, ‘CURVE’, ‘SURFACE’, ‘META’, ‘FONT’, ‘ARMATURE’, ‘LATTICE’, ‘EMPTY’, ‘CAMERA’, ‘LAMP’, ‘SPEAKER’]

Then you can execute the following code snippet to remove all the unused blocks. This way you don't have to close/open Blender or save/open a .blend file:

for block in bpy.data.meshes:
    if block.users == 0:
        bpy.data.meshes.remove(block)

for block in bpy.data.materials:
    if block.users == 0:
        bpy.data.materials.remove(block)

for block in bpy.data.textures:
    if block.users == 0:
        bpy.data.textures.remove(block)

for block in bpy.data.images:
    if block.users == 0:
        bpy.data.images.remove(block)

IMPORTANT NOTE: It looks like that there is some dependencies between some data blocks such as mesh, texture, image and materials. If you do not remove the data blocks on the highest level of the hierarchy, you will not be able to remove other data blocks or you have to take the risk and remove data blocks with users more than 0. So make sure you use the code above in the following order to remove data blocks. This way you can remove all unlinked (users == 0) data blocks:

remove meshes --> remove materials --> remove textures --> remove images

The followings also have data blocks:

bpy.data.curves
bpy.data.lamps
bpy.data.cameras