[question] [docs] Short/mid/long-term status of TorchScript / JIT / torch.jit.trace / FX / symbolic tracing and its replacement by Dynamo

[vadimkantorov]

📚 The doc issue

At OP pytorch/vision#7624 (comment) I stumbled that there might be lack of official communication on short-term / mid-term / long-term status of TorchScript / JIT interpreter.

In that OP case, need to support TorchScript necessitated use of inelegant indexing instead of simpler tensor[..., perm, :, :] which seems not supported by TorchScript (btw is this construct supported by Dynamo?)

Any official information on need to support TorchScript in new code of domain libraries / in general? Does TorchScript continue to receive development? Any deprecation calendar? I would propose that this information / overview (even if no decisions made yet) made very clear directly on main page of https://pytorch.org/docs (preferrably at the top of this long page)

This question comes from the fact that PyTorch had offered many tracing/scripting/compilation technologies over the years, their recipes/tutorials are still all available, and the users need to have information at least about mid-term level plans and recommendations of the core team. My related question on deployment as well: https://discuss.pytorch.org/t/torch-compiles-deployment-story-to-non-python-host-processes/180943/4 - would be good to have this explained very clearly as well

cc @EikanWang @jgong5 @wenzhe-nrv @sanchitintel @svekars @carljparker @ezyang @albanD

[ezyang]

In that OP case, need to support TorchScript necessitated use of inelegant indexing instead of simpler tensor[..., perm, :, :] which seems not supported by TorchScript (btw is this construct supported by Dynamo?)

It is supported in Dynamo.

[vadimkantorov]

The hacks in pytorch/vision#7624 (comment) are new code yet to be merged, so if TorchScript is about to be deprecated, maybe new code should not be developed for its quirks... It seems that some public (and not public) communication on fate of older tech like TorcScript / JIT is badly needed :)

Also, I wonder, can there be now some function decorator to do the if not in scripting: log_usage_once to avoid the repetition, or maybe a way enable these logging somehow externally? so that it doesn't pollute the code everywhere

[soumith]

TorchScript is frozen. It will not receive new feature development.
We have not deprecated it yet, because we dont offer an equivalent replacement yet (we hope to with torch.export).

[vadimkantorov]

If this is imminent, I propose to announce it officially anyways so that torchvision doesn't have to develop newish hacks for torch.jit.script or torch.jit.trace :)