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Comment by brutus1213 | Hacker News Reader

I'm a professional scientist, so let me give my two cents on this matter. Being able to compare your work against SOTA (state of the art) is pretty critical in academic publications. If everyone else in your area uses framework X, it makes a lot of sense for you to do it too. For the last few years, Pytorch has been king for the topics I care about.

However .. one area where Tensorflow shined was the static graph. As our models get even more intensive and needs different parts to execute in parallel, we are seeing some challenges in PyTorch's execution model. For example:

https://pytorch.org/docs/stable/notes/cuda.html#use-nn-paral...

It appears to me that high performance model execution is a bit tricky if you want to do lots of things in parallels. TorchServe also seems quite simple compared to offerings from Tensorflow. So in summary, I think Tensorflow still has some features unmatched by others. It really depends on what you are doing.

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I think Tensorflow made a bad move in academia by being so damn difficult to use on their earlier versions. Sure, their performance was always better than PyTorch's, but when you are an overworked PhD student you care less about your code being efficient and more about your code working at all.

Word got around that debugging PyTorch was relatively painless, those earlier models made it into publications, and now here we are.

But the funny thing is - TF has never been faster than Pytorch. Even when Pytorch just came out they were roughly the same in terms of speed.

Not even remotely true. Or rather, our experiences differ greatly.

The #1 problem with PyTorch is that it’s great if you want to use one videocard for training. Facebook has completely failed to support research scientists that want to do more than this.

It’s no secret that I’m a jax fanboy. But I drink the koolaid because it tastes better than anyone else’s. PyTorch is gonna have a rude wake up call in about… oh, four years. They’ll wake up and hear everyone else comparing them to tensorflow, and it won’t be for the rosy reasons they currently enjoy. PyTorch devs are living in the dark ages without even realizing how much better it is when you have actual control over which parts of your program are JITed, along with an actual execution graph that you can walk and macroexpand lisp-style.

https://jax.readthedocs.io/en/latest/autodidax.html should be required reading for every ML dev, and I can hardly get anyone to look at it. Sometimes I wonder if people just don’t see the steamroller coming for PyTorch. Probably — jax still reads to outsiders as a toy.

Jax might be faster than Pytorch, I don’t know. I’m talking about TF. When I switched from TF to Pytorch 3 years ago, I got no slowdown on any of computer vision models at the time. And I remember looking at a couple of independent benchmarks which also showed them to be roughly the same in speed.

It really depends on what your model is doing. For a time, sequence models were easier to do with Pytorch than TF (due to control flow). On the efficiency side, for vanilla CV models, I also did not observe major differences last time I looked, but when I started to do lots of things in parallel, multi-gpu training, heavy data augmentation, I think TF has some well-engineered capabilities that are not matched yet.

> The #1 problem with PyTorch is that it’s great if you want to use one videocard for training

Incorrect information so confidently stated here. Tons of research papers that use more than one GPU for training, not sure what you're referring to? Standard DDP works fine, for starters.

> how much better it is when you have actual control over which parts of your program are JITed

Can you elaborate? What’s the advantage of controlling which parts are jitted?

Indeed, Google/Alphabet is gradually making the shift to JAX but also to ML Pathways towards models that support multiple tasks and multiple sensory inputs and sparse instead of dense:

See https://blog.google/technology/ai/introducing-pathways-next-...

and Jeff Dean's TED talk: https://www.ted.com/talks/jeff_dean_ai_isn_t_as_smart_as_you...

what are your thoughts on https://github.com/tensorflow/runtime ?

For Academic Papers (the context of this HN topic), JAX and PyTorch makes more sense. A new runtime could be useful in production.

tfrt underlies JAX. In many ways it's the system TF was supposed to have a 5 years ago.

Yes indeed: https://blog.tensorflow.org/2022/02/tfrt-progress-update.htm... The ML Pathways infra is more complicated, and about more efficient scheduling many ops (in a graph) across many accelerators (rather than a small model on a single local GPU)

sure, I know :) I used to work on TPUs at Google in Platforms, much of my time was spent working with Jax and other teams/researchers who found novel ways to break TPU hardware.

What continues to surprise me is that for all his cleverness, Jeff Dean and the rest of the TF leadership spend the last 10 years basically recreating MPI-style high performance computing, but threw away all the learning and rebuilt every bit (except the matrix libraries) from scratch.

TF started with parameter servers (every machine has its own copy of weights and periodically contributes them to a common model, asynchronously) to models that are sharded by data input and model structure that is mapped to the TPU topology (TPUv4 is a 3D wrapped torus). Really not that different from the T3E I used in the 90s.

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