update docs

Author: SkafteNicki

docs/source-pytorch/deploy/production_advanced_2.rst

@@ -7,15 +7,20 @@ Deploy models into production (advanced)
 
 ----
 
-*********************************
-Compile your model to TorchScript
-*********************************
-`TorchScript <https://pytorch.org/docs/stable/jit.html>`_ allows you to serialize your models in a way that it can be loaded in non-Python environments.
-The ``LightningModule`` has a handy method :meth:`~lightning.pytorch.core.LightningModule.to_torchscript` that returns a scripted module which you
-can save or directly use.
+************************************
+Export your model with torch.export
+************************************
+
+`torch.export <https://pytorch.org/docs/stable/export.html>`_ is the recommended way to capture PyTorch models for
+deployment in production environments. It produces a clean intermediate representation with strong soundness guarantees,
+making models suitable for inference optimization and cross-platform deployment.
+You can export any ``LightningModule`` using the ``torch.export.export()`` API.
 
 .. testcode:: python
 
+    import torch
+    from torch.export import export
+
     class SimpleModel(LightningModule):
         def __init__(self):
             super().__init__()
@@ -25,25 +30,27 @@ can save or directly use.
             return torch.relu(self.l1(x.view(x.size(0), -1)))
 
 
-    # create the model
+    # create the model and example input
     model = SimpleModel()
-    script = model.to_torchscript()
+    example_input = torch.randn(1, 64)
 
-    # save for use in production environment
-    torch.jit.save(script, "model.pt")
+    # export the model
+    exported_program = export(model, (example_input,))
 
-It is recommended that you install the latest supported version of PyTorch to use this feature without limitations.
+    # save for use in production environment
+    torch.export.save(exported_program, "model.pt2")
 
-Once you have the exported model, you can run it in PyTorch or C++ runtime:
+It is recommended that you install the latest supported version of PyTorch to use this feature without
+limitations. Once you have the exported model, you can load and run it:
 
 .. code-block:: python
 
     inp = torch.rand(1, 64)
-    scripted_module = torch.jit.load("model.pt")
-    output = scripted_module(inp)
+    loaded_program = torch.export.load("model.pt2")
+    output = loaded_program.module()(inp)
 
 
-If you want to script a different method, you can decorate the method with :func:`torch.jit.export`:
+For more complex models, you can also export specific methods by creating a wrapper:
 
 .. code-block:: python
 
@@ -54,7 +61,6 @@ If you want to script a different method, you can decorate the method with :func
             self.dropout = nn.Dropout()
             self.mc_iteration = mc_iteration
 
-        @torch.jit.export
         def predict_step(self, batch, batch_idx):
             # enable Monte Carlo Dropout
             self.dropout.train()
@@ -66,4 +72,11 @@ If you want to script a different method, you can decorate the method with :func
 
 
     model = LitMCdropoutModel(...)
-    script = model.to_torchscript(file_path="model.pt", method="script")
+    example_batch = torch.randn(32, 10)  # example input
+
+    # Export the predict_step method
+    exported_program = torch.export.export(
+        lambda batch, idx: model.predict_step(batch, idx),
+        (example_batch, 0)
+    )
+    torch.export.save(exported_program, "mc_dropout_model.pt2")