Revert "[dcp] Add ZStandard transformer (#143360)"

This reverts commit 7b56b039afe2b4a4038c09d8b6cb1597823f3d5f.

Reverted https://github.com/pytorch/pytorch/pull/143360 on behalf of https://github.com/atalman due to Broke 3.13t builds please test with ciflow/binaries label attached ([comment](https://github.com/pytorch/pytorch/pull/143360#issuecomment-2603433066))

.ci/docker/requirements-ci.txt

@@ -363,7 +363,6 @@ pwlf==2.2.1 ; python_version >= "3.8"
 astunparse
 PyYAML
 setuptools
-zstandard
 
 ninja==1.11.1 ; platform_machine == "aarch64"
 scons==4.5.2 ; platform_machine == "aarch64"

requirements.txt

@@ -19,4 +19,3 @@ setuptools
 sympy==1.13.3
 types-dataclasses
 typing-extensions>=4.10.0
-zstandard

test/distributed/checkpoint/test_dtensor_resharding.py

@@ -8,7 +8,6 @@ from torch.distributed._tensor import (
     Shard,
     zeros,
 )
-from torch.distributed.checkpoint._extension import ZStandard
 from torch.testing._internal.common_utils import (
     instantiate_parametrized_tests,
     parametrize,
@@ -59,7 +58,7 @@ class TestDTensorReshardPlacementChange(DTensorTestBase):
     @with_comms
     @skip_if_lt_x_gpu(2)
     @with_temp_dir
-    @parametrize("extensions", [None, [Rot13Example()], [ZStandard()]])
+    @parametrize("extensions", [None, [Rot13Example()]])
     def test_1d_to_1d_reshard_placement_change(self, extensions) -> None:
         CHECKPOINT_DIR = self.temp_dir
 

test/distributed/checkpoint/test_file_system_checkpoint.py

@@ -22,7 +22,6 @@ from torch.distributed.checkpoint import (
     load_state_dict,
     save_state_dict,
 )
-from torch.distributed.checkpoint._extension import ZStandard
 from torch.testing._internal.common_distributed import requires_nccl, skip_if_lt_x_gpu
 from torch.testing._internal.common_utils import (
     instantiate_parametrized_tests,
@@ -166,7 +165,7 @@ class TestDistributedStateDictSaveLoadWithSharedTensor(ShardedTensorTestBase):
     @with_comms(init_rpc=False)
     @skip_if_lt_x_gpu(2)
     @requires_nccl()
-    @parametrize("extensions", [None, [Rot13Example()], [ZStandard()]])
+    @parametrize("extensions", [None, [Rot13Example()]])
     def test_read_write_shard_tensor(self, extensions) -> None:
         paths = [tempfile.mkdtemp()]
         dist.broadcast_object_list(paths)

test/distributed/checkpoint/test_file_system_checkpoint_cpu.py

@@ -22,7 +22,6 @@ from torch.distributed.checkpoint import (
     save,
     save_state_dict,
 )
-from torch.distributed.checkpoint._extension import ZStandard
 from torch.distributed.checkpoint.stateful import Stateful
 from torch.testing._internal.common_utils import (
     instantiate_parametrized_tests,
@@ -192,39 +191,6 @@ class TestDistributedStateDictSaveLoadRot13(TestCase):
             assert_state_dict_equal(self, state_dict_to_load_to, state_dict_to_save)
 
 
-class TestDistributedStateDictSaveLoadZStandard(TestCase):
-    @parametrize("thread_count", _THREAD_COUNTS)
-    def test_read_write_only_tensor(self, thread_count) -> None:
-        with tempfile.TemporaryDirectory() as path:
-            state_dict_to_save = MyTestModule().state_dict()
-            state_dict_to_save["test_blob"] = BlobState(b"SomeBlobForTesting")
-
-            fs_writer = FileSystemWriter(
-                path=path,
-                thread_count=thread_count,
-                _extensions=[ZStandard()],
-            )
-            save(
-                state_dict=state_dict_to_save,
-                storage_writer=fs_writer,
-            )
-
-            state_dict_to_load_to = MyTestModule().state_dict()
-            state_dict_to_load_to["test_blob"] = BlobState(b"")
-
-            with self.assertRaises(AssertionError):
-                assert_state_dict_equal(self, state_dict_to_load_to, state_dict_to_save)
-
-            # Load from file without any resharding
-            fs_reader = FileSystemReader(path=path)
-            load(
-                state_dict=state_dict_to_load_to,
-                storage_reader=fs_reader,
-            )
-
-            assert_state_dict_equal(self, state_dict_to_load_to, state_dict_to_save)
-
-
 class TestDistributedStateDictSaveLoadWithSharedTensor(ShardedTensorTestBase):
     @property
     def world_size(self) -> int:
@@ -559,7 +525,6 @@ class TestDistributedReshardOnLoad(ShardedTensorTestBase):
 instantiate_parametrized_tests(TestDistributedStateDictSaveLoad)
 instantiate_parametrized_tests(TestDistributedStateDictSaveLoadRot13)
 instantiate_parametrized_tests(TestDistributedStateDictSaveLoadWithSharedTensor)
-instantiate_parametrized_tests(TestDistributedStateDictSaveLoadZStandard)
 instantiate_parametrized_tests(TestDistributedReshardOnLoad)
 
 if __name__ == "__main__":

torch/distributed/checkpoint/_extension.py

@@ -1,8 +1,6 @@
 # Copyright (c) Meta Platforms, Inc. and affiliates
 
 import abc
-import importlib.util
-import sys
 from collections.abc import Sequence
 from typing import IO, Type
 
@@ -11,24 +9,7 @@ from typing import IO, Type
 # change.  Feedback and bug fixes are always welcome.
 
 
-zstandard_module_name = "zstandard"
+__all__ = ["Extension", "StreamTransformExtension", "ExtensionRegistry"]
-
-if (zstandard := sys.modules.get(zstandard_module_name, None)) is not None:
-    pass
-elif (zstandard_spec := importlib.util.find_spec(zstandard_module_name)) is not None:
-    zstandard = importlib.util.module_from_spec(zstandard_spec)
-    sys.modules[zstandard_module_name] = zstandard
-    zstandard_spec.loader.exec_module(zstandard)  # type: ignore[union-attr]
-else:
-    zstandard = None
-
-
-__all__ = [
-    "Extension",
-    "StreamTransformExtension",
-    "ZStandard",
-    "ExtensionRegistry",
-]
 
 
 class Extension(abc.ABC):
@@ -91,50 +72,10 @@ class StreamTransformExtension(Extension):
         """
 
 
-class ZStandard(StreamTransformExtension):
-    @staticmethod
-    def is_available() -> bool:
-        return zstandard is not None
-
-    @staticmethod
-    def from_descriptor(version: str) -> "ZStandard":
-        if version.partition(".")[0] != "1":
-            raise ValueError(f"Unknown extension {version=}")
-        if not ZStandard.is_available():
-            raise ValueError(
-                f"Stream with ZStandard compression cannot be processed because no module named '{zstandard_module_name}'"
-            )
-        return ZStandard()
-
-    @staticmethod
-    def registry_name() -> str:
-        return "stream.zstd"
-
-    def __init__(self) -> None:
-        super().__init__()
-        if not ZStandard.is_available():
-            raise ValueError(
-                f"ZStandard extension is unavailable because no module named '{zstandard_module_name}'"
-            )
-
-    def get_descriptor(self) -> str:
-        return f"{self.registry_name()}/1"
-
-    def transform_to(self, output: IO[bytes]) -> IO[bytes]:
-        compressor = zstandard.ZstdCompressor()  # type: ignore[union-attr]
-        return compressor.stream_writer(output)
-
-    def transform_from(self, input: IO[bytes]) -> IO[bytes]:
-        decompressor = zstandard.ZstdDecompressor()  # type: ignore[union-attr]
-        return decompressor.stream_reader(input)
-
-
 class ExtensionRegistry:
     def __init__(self) -> None:
         # Populate default registry contents
-        self.extensions: dict[str, Type[Extension]] = {
+        self.extensions: dict[str, Type[Extension]] = {}
-            cls.registry_name(): cls for cls in (ZStandard,)
-        }
 
     def register(self, cls: Type[Extension]) -> None:
         self.extensions[cls.registry_name()] = cls