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import dataclasses
import io
from typing import List, Tuple, Dict, Any, Union, cast
import torch
from torch.distributed._shard._utils import narrow_tensor_by_index
from torch.distributed._shard.sharded_tensor import ShardedTensor
from .planner import (
SavePlanner,
LoadPlanner,
SavePlan,
LoadPlan,
ReadItem,
WriteItem,
WriteItemType,
)
from .metadata import (
BytesStorageMetadata,
TensorStorageMetadata,
MetadataIndex,
Metadata,
STATE_DICT_TYPE,
STORAGE_TYPES
)
from .planner_helpers import (
_create_read_items,
_create_write_items,
_create_default_metadata_only_plan
)
from .utils import (
find_state_dict_object
)
class DefaultSavePlanner(SavePlanner):
def init(self, state_dict: Dict[str, Any], is_coordinator: bool) -> None:
self.state_dict = state_dict
self.is_coordinator = is_coordinator
def create_local_plan(self) -> SavePlan:
self.plan = create_default_local_save_plan(self.state_dict, self.is_coordinator)
return self.plan
def create_global_plan(self, all_plans: List[SavePlan]) -> Tuple[List[SavePlan], Metadata]:
self.global_plan, self.metadata = create_default_global_save_plan(all_plans)
return self.global_plan, self.metadata
def finish_plan(self, new_plan: SavePlan) -> SavePlan:
self.plan = new_plan
return new_plan
def resolve_data(self, write_item: WriteItem) -> Union[torch.Tensor, io.BytesIO]:
object = self.lookup_object(write_item.index)
return self.transform_object(write_item, object)
def lookup_object(self, index: MetadataIndex) -> Any:
"""
This is an extension from the planner interface to make it easy to extend the default planner
"""
return find_state_dict_object(self.state_dict, index)
def transform_object(self, write_item: WriteItem, object: Any):
"""
This is an extension from the planner interface to make it easy to extend the default planner
"""
if write_item.type == WriteItemType.BYTE_IO:
bytes = io.BytesIO()
torch.save(object, bytes)
object = bytes
return object
class DefaultLoadPlanner(LoadPlanner):
def init(self, state_dict: STATE_DICT_TYPE, metadata: Metadata, is_coordinator: bool) -> None:
self.state_dict = state_dict
self.metadata = metadata
self.is_coordinator = is_coordinator
def create_local_plan(self) -> LoadPlan:
return create_default_local_load_plan(self.state_dict, self.metadata)
def create_global_plan(self, global_plan: List[LoadPlan]) -> List[LoadPlan]:
return create_default_global_load_plan(global_plan)
def finish_plan(self, new_plan: LoadPlan) -> LoadPlan:
return new_plan
def load_bytes(self, read_item: ReadItem, value: io.BytesIO) -> None:
self.state_dict[read_item.dest_index.fqn] = torch.load(value)
def resolve_tensor(self, read_item: ReadItem):
tensor = self.lookup_tensor(read_item.dest_index)
return self.transform_tensor(read_item, tensor)
def commit_tensor(self, read_item: ReadItem, tensor: torch.Tensor) -> None:
pass
def lookup_tensor(self, index: MetadataIndex) -> torch.Tensor:
"""
This is an extension from the planner interface to make it easy to extend the default planner
"""
return find_state_dict_object(self.state_dict, index)
def transform_tensor(self, read_item: ReadItem, tensor: torch.Tensor):
"""
This is an extension from the planner interface to make it easy to extend the default planner
"""
return narrow_tensor_by_index(tensor, read_item.dest_offsets, read_item.lengths)
def create_default_local_load_plan(
state_dict: Dict[str, Any],
metadata: Metadata,
) -> LoadPlan:
requests = []
"""
Create the ``LoadPlan`` used by DefaultLoadPlanner.
It produces one read item per value in ``state_dict`` using the metadata in ``metadata``.
The default behavior is to match key exactly between state_dict and metadata.
It handles resharding by issuing multiple read requests against storage in order to match
load requirements.
"""
for fqn, obj in state_dict.items():
md = metadata.state_dict_metadata[fqn]
requests += _create_read_items(fqn, md, obj)
return LoadPlan(requests)
def create_default_global_load_plan(all_plans: List[LoadPlan]) -> List[LoadPlan]:
"""
Create global load plan used by DefaultLoadPlanner.
The default load behavior involved no global coordination and this function
currently doesn't change the local plans.
"""
return all_plans
def create_default_local_save_plan(state_dict: Dict[str, Any], is_coordinator: bool) -> SavePlan:
"""
Create the ``SavePlan`` used by DefaultSavePlanner.
On non-coordinator ranks, this function ignores tensors and non-tensor objects,
only producing writes for ShardedTensor objects.
On the coordinator rank, produce writes for all values.
"""
requests = []
for fqn, obj in state_dict.items():
if isinstance(obj, ShardedTensor) or is_coordinator:
requests += _create_write_items(fqn, obj)
return SavePlan(requests)
def create_default_global_save_plan(all_plans: List[SavePlan]) -> Tuple[List[SavePlan], Metadata]:
"""
Create the global plan and metadata used by DefaultSavePlanner.
Metadata is produced by concatenating the metadata of all ``WriteItem`` from the supplied plans.
The only global planning change is to update index hints in all ``MetadataIndex`` objects.
"""
md: Dict[str, STORAGE_TYPES] = {}
new_plans = []
for plan in all_plans:
new_items = []
for item in plan.items:
if not item.type == WriteItemType.SHARD:
assert item.index.fqn not in md
if item.type == WriteItemType.BYTE_IO:
md[item.index.fqn] = BytesStorageMetadata()
new_items.append(item)
else:
assert item.tensor_data is not None
tensor_md = cast(
TensorStorageMetadata,
md.setdefault(item.index.fqn, TensorStorageMetadata(
properties=item.tensor_data.properties,
size=item.tensor_data.size,
chunks=[],
))
)
new_index = dataclasses.replace(item.index, index=len(tensor_md.chunks))
new_item = dataclasses.replace(item, index=new_index)
new_items.append(new_item)
assert item.tensor_data.chunk is not None, f"Cannot create MD for tensor without bounds. FQN: {item.index.fqn}"
tensor_md.chunks.append(item.tensor_data.chunk)
new_plans.append(dataclasses.replace(plan, items=new_items))
return (new_plans, Metadata(md))
def _create_default_local_metadata(state_dict: STATE_DICT_TYPE) -> Metadata:
"""
Return the ``Metadata`` if DefaultSavePlanner was used to checkpoint ``state_dict``.
"""
plan = _create_default_metadata_only_plan(state_dict)
_, md = create_default_global_save_plan([plan])
return md
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