Seeing such clever use of mmap makes me dread to imagine how much Python spaghetti probably tanks OpenAI's and other "big ML" shops' infra when they should've trusted in zero copy solutions.
Perhaps SWE is dead after all, but LLMs didn't kill it...
Probably not all that much. All of the Python numeric computing frameworks (Numpy, PyTorch, TensorFlow, etc.) are basically just wrappers for lower level C++/C/Fortran code. Unless you’re doing something boneheaded and converting framework-native tensors to Python objects, passing tensors around within a framework essentially just passes a pointer around, which has marginal overhead even when encapsulated in a bloated Python object.
Indeed, a huge number of PyTorch operations are explicitly zero copy: https://pytorch.org/docs/stable/tensor_view.html
This leads to all sorts of bugs and breaking changes that are cool in an academic or hobbyist setting but a total headache on a large production system.
Suppose you have a big piece of compute hardware (e.g. at a university) which is shared by multiple users. They all want to come in and play with these models. Each one is tens to hundreds of gigabytes. Is each user supposed to have their own copy in their home directory?
But now we encounter this broken nonsense because solved problems get unsolved by bad software.