State dict serialization

tests/test_state_dict.py

@@ -14,20 +14,23 @@
 import pytest
 
 import torch
+
+import torch.distributed as dist
 import torch.distributed.checkpoint as dcp
 import torch.nn as nn
-
 import torchstore as ts
 
 from monarch.actor import Actor, current_rank, endpoint
+
 from torch.distributed.checkpoint._nested_dict import flatten_state_dict
 from torch.distributed.checkpoint.state_dict import (
     get_model_state_dict,
     get_optimizer_state_dict,
 )
-from torch.distributed.device_mesh import init_device_mesh
+from torch.distributed.device_mesh import DeviceMesh, init_device_mesh
 from torch.distributed.fsdp import fully_shard
-from torch.distributed.tensor import DTensor
+from torch.distributed.tensor import DTensor, Replicate
+from torchstore.state_dict_utils import TensorReference, TorchStoreStateDict
 from torchstore.utils import spawn_actors
 
 from .utils import main, transport_plus_strategy_params
@@ -38,6 +41,100 @@
 MODEL_LINER_LENGTH = 10
 
 
+def _setup_process_group():
+    """Set up minimal distributed environment for DTensor testing."""
+
+    if not dist.is_initialized():
+        # Set minimal environment variables for single process
+        import os
+
+        os.environ.setdefault("MASTER_ADDR", "127.0.0.1")
+        os.environ.setdefault(
+            "MASTER_PORT", "29501"
+        )  # Different port to avoid conflicts
+        os.environ.setdefault("RANK", "0")
+        os.environ.setdefault("WORLD_SIZE", "1")
+
+        # Initialize single-process group
+        dist.init_process_group(
+            backend="gloo",  # CPU backend
+            rank=0,
+            world_size=1,
+        )
+        return True
+
+
+def _verify_tensor_references(torchstore_state_dict, flattened_original):
+    """Utility function to verify TensorReference objects in flattened state dict."""
+    for key, original_value in flattened_original.items():
+        torchstore_value = torchstore_state_dict.flattened_state_dict[key]
+
+        if isinstance(original_value, torch.Tensor):
+            if hasattr(original_value, "_local_tensor"):  # DTensor check
+                # DTensor should be converted to TensorReference with tensor_slice
+                assert isinstance(torchstore_value, TensorReference)
+                assert (
+                    torchstore_value.tensor_slice is not None
+                ), f"DTensor at {key} should have tensor_slice"
+                assert (
+                    torchstore_value.device_mesh is not None
+                ), f"DTensor at {key} should have device_mesh"
+                assert (
+                    torchstore_value.placements is not None
+                ), f"DTensor at {key} should have placements"
+
+                # Verify local tensor metadata
+                local_tensor = original_value._local_tensor
+                assert torchstore_value.shape == tuple(local_tensor.shape)
+                assert torchstore_value.dtype == local_tensor.dtype
+            else:
+                # Regular tensor should not have tensor_slice
+                assert isinstance(torchstore_value, TensorReference)
+                assert (
+                    torchstore_value.tensor_slice is None
+                ), f"Regular tensor at {key} should not have tensor_slice"
+                assert torchstore_value.shape == tuple(original_value.shape)
+                assert torchstore_value.dtype == original_value.dtype
+
+
+def _verify_reconstructed_state_dict(flattened_original, flattened_reconstructed):
+    """Utility function to verify reconstructed state dict matches original."""
+    for key, original_value in flattened_original.items():
+        reconstructed_value = flattened_reconstructed[key]
+
+        if hasattr(original_value, "_local_tensor"):  # DTensor check
+            # Should be reconstructed as DTensor
+            assert hasattr(
+                reconstructed_value, "_local_tensor"
+            ), f"Expected DTensor for {key}"
+
+            # Verify local tensor data matches
+            assert torch.equal(
+                original_value._local_tensor, reconstructed_value._local_tensor
+            ), f"Local tensor data mismatch for {key}"
+
+            # Verify global shape matches
+            assert (
+                original_value.shape == reconstructed_value.shape
+            ), f"Global shape mismatch for {key}"
+
+            # Verify placements match
+            assert (
+                original_value.placements == reconstructed_value.placements
+            ), f"Placements mismatch for {key}"
+
+        elif isinstance(original_value, torch.Tensor):
+            # Regular tensors should remain the same
+            assert torch.equal(
+                original_value, reconstructed_value
+            ), f"Regular tensor mismatch for {key}"
+        else:
+            # Non-tensor values should be preserved
+            assert (
+                original_value == reconstructed_value
+            ), f"Non-tensor value mismatch for {key}"
+
+
 class UnitModule(nn.Module):
     def __init__(self, device: torch.device):
         super().__init__()
@@ -296,5 +393,182 @@ def _assert_equal_state_dict(state_dict1, state_dict2):
             ), f"{key=} {flattened_state_dict_1[key]=} {flattened_state_dict_2[key]=}"
 
 
+def test_torchstore_state_dict():
+    """Test TorchStoreStateDict class with various tensor types and reconstruction."""
+
+    # Create a state dict with various tensor types and shapes
+    original_state_dict = {
+        # Scalar tensor (0D)
+        "scalar": torch.tensor(42.5, dtype=torch.float32),
+        # 1D tensors with different dtypes
+        "vector_float": torch.randn(10, dtype=torch.float32),
+        "vector_int": torch.randint(0, 100, (5,), dtype=torch.int64),
+        "vector_half": torch.randn(8, dtype=torch.float16),
+        # 2D tensors with different dtypes
+        "matrix_float": torch.randn(3, 4, dtype=torch.float32),
+        "matrix_double": torch.randn(2, 3, dtype=torch.float64),
+        "matrix_int": torch.randint(-50, 50, (4, 2), dtype=torch.int32),
+        # Nested structure
+        "model": {
+            "layer1": {
+                "weight": torch.randn(5, 3, dtype=torch.float32),
+                "bias": torch.randn(5, dtype=torch.float32),
+            },
+            "layer2": {
+                "weight": torch.randn(2, 5, dtype=torch.float32),
+                "bias": torch.randn(2, dtype=torch.float32),
+            },
+        },
+        # Mixed with non-tensor data
+        "metadata": {
+            "epoch": 10,
+            "learning_rate": 0.001,
+            "optimizer_state": torch.randn(3, 3, dtype=torch.float32),
+        },
+        # List with tensors (note: flattened state dict doesn't preserve list structure)
+        "layer_weights": [
+            torch.randn(2, 2, dtype=torch.float32),
+            torch.tensor(123, dtype=torch.int32),
+        ],
+    }
+
+    # Create TorchStoreStateDict
+    torchstore_state_dict = TorchStoreStateDict.from_state_dict(original_state_dict)
+
+    # Verify blob properties
+    blob = torchstore_state_dict.tensor_blob
+    assert blob.dtype == torch.uint8, f"Expected uint8 blob, got {blob.dtype}"
+    assert blob.dim() == 1, f"Expected 1D blob, got {blob.dim()}D"
+
+    # 1. Flatten original state dict
+    original_flattened, _ = flatten_state_dict(original_state_dict)
+
+    # 2. Verify keys match between original flattened and torchstore flattened state dict
+    assert set(original_flattened.keys()) == set(
+        torchstore_state_dict.flattened_state_dict.keys()
+    ), "Keys don't match between original and torchstore flattened state dicts"
+
+    # 3. Verify tensor references and calculate total size
+    _verify_tensor_references(torchstore_state_dict, original_flattened)
+
+    # Calculate total size for blob verification
+    total_size = 0
+    for key, original_value in original_flattened.items():
+        if isinstance(original_value, torch.Tensor):
+            tensor_to_size = (
+                original_value._local_tensor
+                if hasattr(original_value, "_local_tensor")
+                else original_value
+            )
+            total_size += tensor_to_size.numel() * tensor_to_size.element_size()
+
+    # Verify tensor blob size matches total size
+    assert (
+        len(blob) == total_size
+    ), f"Tensor blob size {len(blob)} doesn't match expected total size {total_size}"
+
+    # Reconstruct the state dict
+    reconstructed_state_dict = torchstore_state_dict.to_state_dict()
+
+    # Compare flattened versions - simpler than recursive comparison
+    original_flattened, original_mapping = flatten_state_dict(original_state_dict)
+    reconstructed_flattened, reconstructed_mapping = flatten_state_dict(
+        reconstructed_state_dict
+    )
+
+    # Verify mappings are identical (structure preserved)
+    assert (
+        original_mapping == reconstructed_mapping
+    ), "State dict structure mappings don't match"
+
+    # Verify keys match
+    assert set(original_flattened.keys()) == set(
+        reconstructed_flattened.keys()
+    ), "Flattened keys don't match"
+
+    # Verify reconstruction using utility function
+    _verify_reconstructed_state_dict(original_flattened, reconstructed_flattened)
+
+
+def test_torchstore_state_dict_edge_cases():
+    """Test edge cases for TorchStoreStateDict."""
+
+    # Test empty state dict
+    empty_dict = {}
+    torchstore_state_dict = TorchStoreStateDict.from_state_dict(empty_dict)
+    reconstructed = torchstore_state_dict.to_state_dict()
+    assert reconstructed == {}
+
+    # Test state dict with no tensors
+    no_tensors = {"a": 1, "b": {"c": "hello", "d": [1, 2, 3]}}
+    torchstore_state_dict = TorchStoreStateDict.from_state_dict(no_tensors)
+    reconstructed = torchstore_state_dict.to_state_dict()
+    assert reconstructed == no_tensors
+
+    # Test scalar tensor edge case
+    scalar_dict = {"scalar": torch.tensor(3.14159)}
+    torchstore_state_dict = TorchStoreStateDict.from_state_dict(scalar_dict)
+    # Check flattened state dict has TensorReference
+    reconstructed = torchstore_state_dict.to_state_dict()
+    assert torch.equal(scalar_dict["scalar"], reconstructed["scalar"])
+
+    # Test different dtypes
+    dtype_dict = {
+        "bool": torch.tensor([True, False, True]),
+        "uint8": torch.randint(0, 255, (5,), dtype=torch.uint8),
+        "int8": torch.randint(-128, 127, (3,), dtype=torch.int8),
+        "int16": torch.randint(-1000, 1000, (4,), dtype=torch.int16),
+        "bfloat16": torch.randn(3, dtype=torch.bfloat16),
+    }
+
+    torchstore_state_dict = TorchStoreStateDict.from_state_dict(dtype_dict)
+    reconstructed = torchstore_state_dict.to_state_dict()
+
+    for key in dtype_dict:
+        assert torch.equal(
+            dtype_dict[key], reconstructed[key]
+        ), f"Mismatch for dtype {key}"
+
+
+def test_torchstore_state_dict_with_dtensor():
+    """Test TorchStoreStateDict with DTensor support."""
+    _setup_process_group()
+
+    # Create single-device mesh (CPU only)
+    device_mesh = DeviceMesh("cpu", [0])
+
+    # Create DTensor from local tensor
+    local_tensor = torch.randn(4, 6, dtype=torch.float32)
+    dtensor = DTensor.from_local(local_tensor, device_mesh, [Replicate()])
+
+    # Create state dict with DTensor and regular tensor
+    original_state_dict = {
+        "regular_tensor": torch.randn(3, 3),
+        "dtensor": dtensor,
+        "nested": {
+            "another_dtensor": DTensor.from_local(
+                torch.ones(2, 3), device_mesh, [Replicate()]
+            ),
+            "metadata": {"test": "value"},
+        },
+    }
+
+    # Test serialization
+    torchstore_state_dict = TorchStoreStateDict.from_state_dict(original_state_dict)
+
+    # Verify DTensor metadata is preserved using utility function
+    flattened_original, _ = flatten_state_dict(original_state_dict)
+    _verify_tensor_references(torchstore_state_dict, flattened_original)
+
+    # Test deserialization
+    reconstructed_state_dict = torchstore_state_dict.to_state_dict()
+
+    # Verify reconstruction using utility function
+    flattened_reconstructed, _ = flatten_state_dict(reconstructed_state_dict)
+    _verify_reconstructed_state_dict(flattened_original, flattened_reconstructed)
+
+    dist.destroy_process_group()
+
+
 if __name__ == "__main__":
     main(__file__)

torchstore/dtensor_utils.py

@@ -0,0 +1,65 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+from typing import Tuple
+
+import torch
+from torch.distributed.tensor import DTensor, Placement
+from torch.distributed.tensor._utils import _compute_local_shape_and_global_offset
+
+
+def create_tensor_slice_from_dtensor(dtensor: DTensor) -> "TensorSlice":
+    """
+    Create a TensorSlice from a DTensor.
+
+    Args:
+        dtensor: The DTensor to extract metadata from
+
+    Returns:
+        TensorSlice containing the distributed tensor metadata
+    """
+    from torchstore.transport.pipe import TensorSlice
+
+    coordinates = dtensor.device_mesh.get_coordinate()
+    _, offsets = _compute_local_shape_and_global_offset(
+        dtensor.shape,
+        mesh_shape=dtensor.device_mesh.shape,
+        my_coordinate=coordinates,
+        placements=dtensor.placements,
+    )
+
+    return TensorSlice(
+        offsets=offsets,
+        coordinates=coordinates,
+        global_shape=dtensor.shape,
+        local_shape=dtensor._local_tensor.shape,
+        mesh_shape=dtensor.device_mesh.shape,
+    )
+
+
+def reconstruct_dtensor_from_local_tensor(
+    local_tensor: torch.Tensor,
+    tensor_slice: "TensorSlice",
+    device_mesh: torch.distributed.DeviceMesh,
+    placements: Tuple[Placement, ...],
+) -> DTensor:
+    """
+    Reconstruct a DTensor from local tensor data and TensorSlice metadata.
+
+    Args:
+        local_tensor: The local tensor shard
+        tensor_slice: TensorSlice containing distributed metadata
+        device_mesh: The device mesh for the DTensor
+        placements: The placements for the DTensor
+
+    Returns:
+        Reconstructed DTensor
+    """
+    return DTensor.from_local(
+        local_tensor=local_tensor,
+        device_mesh=device_mesh,
+        placements=placements,
+    )