Memory leaks during indexing

[one-some]

it seems that during indexing facebook/opt-2.7b, there are two problems:

• there's a memory usage spike of 5GB each time one of the archives is read (makes sense, this is probably the pickle file being deserialized)
• memory usage permanently rises by 200-600MB (!!!) each time the model is indexed

the pickle spike is a little weird because in theory we're intercepting tensor creation stuff with the pickle patch/subclass thingey, so maybe its reading the file to a memory buffer somewhere for speed. in that case we might be able to use a streaming capable pickle module, but i do wonder what kind of effect that will have on one big tree-like object such as an nn.Module

the 500ish MB is a bit more concerning, no clue what could be causing that (caching?)