A few reasons that I am aware of:

pytorch APIs for optimizing 4 and otherwise preparing a model for production are still fairly new and rough around the edges
FB described themselves as relying on caffe for production inference 3 – but caffe seems to have been “merged” into pytorch in 2018 and the result for us the end users seems to be a somewhat confused mix of possible runtimes (or “backends”): python, JIT traced, JIT scripted, ONNX. If you quantize a model you might not be able to export it to ONNX. Or even save it. And so on – things just don’t feel properly cooked yet.


Because at the end all you need is an input, and you shall give back an output for further processing.

Hmm, a lot of people want more. Can you run the above on mobile? How about a production environment that doesn’t have python at all?