[michal2409]

• I, the PR author, have personally reviewed every line of this PR.

What does this PR do?

Fix loading torch_dist checkpoints on PyTorch builds that include pytorch/pytorch#194251, which adds a strides field to torch.distributed.checkpoint.metadata.TensorProperties.

TorchDistLoadShardedStrategy.load_tensors_metadata builds each placeholder tensor with torch.empty(tp.size, **tp.properties.__dict__, device='meta'). torch.empty does not accept strides, so load_tensors_metadata, load_sharded_metadata and dist_checkpointing.load fail on every torch_dist checkpoint:

TypeError: empty() got an unexpected keyword argument 'strides'

Checkpoints written by older PyTorch versions fail too, because the new TensorProperties.__setstate__ sets strides = None when unpickling them.

The placeholder only supplies the shape and dtype of the ShardedTensor (.without_data() drops the tensor itself), so pass only the dtype, as PyTorch's _EmptyStateDictLoadPlanner does.

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Issue tracking

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Linked issue: none (small bug fix).

Contribution process

Pre-checks

• I have added relevant unit tests
• I have added relevant functional tests
• If this PR adds or changes a GPU kernel (Triton, jit_fuser/torch.compile, CUDA extension, TE or external-library dispatch, or a scatter/index accumulation), I have added or updated its bit-exact determinism test and registered it in tests/unit_tests/determinism/kernels/manifest.py (guide)
• I have added proper typing to my code Typing guidelines
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Validation

On a PyTorch build that includes pytorch/pytorch#194251 (2.15.0a0):

• The new test_load_tensors_metadata_ignores_tensor_strides fails without the fix and passes with it.
• load_tensors_metadata and load_sharded_metadata on a torch_dist checkpoint written by an older PyTorch (925 tensors) raise the TypeError without the fix and pass with it.
• A dist_checkpointing.save, load_tensors_metadata, dist_checkpointing.load round trip raises the TypeError without the fix and passes with it; the loaded tensors match.
• black 26.3.0, isort 5.13.2, ruff 0.9 and pylint 3.2.6 with the repository configs report nothing new on the changed files.

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[gautham-kollu]

/ok to test 188b025

[gautham-kollu]

/ok to test 188b025

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