Register ModelOutput as supported torch pytree nodes (#26618)

* Register ModelOutput as supported torch pytree nodes

* Test ModelOutput as supported torch pytree nodes

* Update type hints for pytree unflatten functions
This commit is contained in:
Xuehai Pan 2023-10-24 17:02:40 +08:00 committed by GitHub
parent ede051f1b8
commit cc7803c0a6
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2 changed files with 30 additions and 13 deletions

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@ -22,7 +22,7 @@ from collections.abc import MutableMapping
from contextlib import ExitStack, contextmanager
from dataclasses import fields, is_dataclass
from enum import Enum
from typing import Any, ContextManager, List, Tuple
from typing import Any, ContextManager, Iterable, List, Tuple
import numpy as np
@ -306,12 +306,10 @@ class ModelOutput(OrderedDict):
`static_graph=True` with modules that output `ModelOutput` subclasses.
"""
if is_torch_available():
import torch.utils._pytree
torch.utils._pytree._register_pytree_node(
_torch_pytree._register_pytree_node(
cls,
torch.utils._pytree._dict_flatten,
lambda values, context: cls(**torch.utils._pytree._dict_unflatten(values, context)),
_model_output_flatten,
_model_output_unflatten,
)
def __init__(self, *args, **kwargs):
@ -430,6 +428,23 @@ class ModelOutput(OrderedDict):
return tuple(self[k] for k in self.keys())
if is_torch_available():
import torch.utils._pytree as _torch_pytree
def _model_output_flatten(output: ModelOutput) -> Tuple[List[Any], "_torch_pytree.Context"]:
return list(output.values()), (type(output), list(output.keys()))
def _model_output_unflatten(values: Iterable[Any], context: "_torch_pytree.Context") -> ModelOutput:
output_type, keys = context
return output_type(**dict(zip(keys, values)))
_torch_pytree._register_pytree_node(
ModelOutput,
_model_output_flatten,
_model_output_unflatten,
)
class ExplicitEnum(str, Enum):
"""
Enum with more explicit error message for missing values.

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@ -126,22 +126,24 @@ class ModelOutputTester(unittest.TestCase):
def test_torch_pytree(self):
# ensure torch.utils._pytree treats ModelOutput subclasses as nodes (and not leaves)
# this is important for DistributedDataParallel gradient synchronization with static_graph=True
import torch
import torch.utils._pytree
import torch.utils._pytree as pytree
x = ModelOutput({"a": 1.0, "c": 2.0})
self.assertFalse(pytree._is_leaf(x))
x = ModelOutputTest(a=1.0, c=2.0)
self.assertFalse(torch.utils._pytree._is_leaf(x))
self.assertFalse(pytree._is_leaf(x))
expected_flat_outs = [1.0, 2.0]
expected_tree_spec = torch.utils._pytree.TreeSpec(
ModelOutputTest, ["a", "c"], [torch.utils._pytree.LeafSpec(), torch.utils._pytree.LeafSpec()]
expected_tree_spec = pytree.TreeSpec(
ModelOutputTest, (ModelOutputTest, ["a", "c"]), [pytree.LeafSpec(), pytree.LeafSpec()]
)
actual_flat_outs, actual_tree_spec = torch.utils._pytree.tree_flatten(x)
actual_flat_outs, actual_tree_spec = pytree.tree_flatten(x)
self.assertEqual(expected_flat_outs, actual_flat_outs)
self.assertEqual(expected_tree_spec, actual_tree_spec)
unflattened_x = torch.utils._pytree.tree_unflatten(actual_flat_outs, actual_tree_spec)
unflattened_x = pytree.tree_unflatten(actual_flat_outs, actual_tree_spec)
self.assertEqual(x, unflattened_x)