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- # Copyright 2021 The HuggingFace Team. All rights reserved.
- #
- # Licensed under the Apache License, Version 2.0 (the "License");
- # you may not use this file except in compliance with the License.
- # You may obtain a copy of the License at
- #
- # http://www.apache.org/licenses/LICENSE-2.0
- #
- # Unless required by applicable law or agreed to in writing, software
- # distributed under the License is distributed on an "AS IS" BASIS,
- # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- # See the License for the specific language governing permissions and
- # limitations under the License.
- import importlib
- import math
- from contextlib import suppress
- from typing import Callable, Optional, Union
- import torch
- from packaging import version
- from torch.utils.data import BatchSampler, DataLoader, IterableDataset, RandomSampler
- from .logging import get_logger
- from .state import DistributedType, GradientState, PartialState, is_torch_xla_available
- from .utils import (
- RNGType,
- broadcast,
- broadcast_object_list,
- compare_versions,
- concatenate,
- find_batch_size,
- get_data_structure,
- initialize_tensors,
- is_datasets_available,
- is_torch_version,
- is_torchdata_stateful_dataloader_available,
- send_to_device,
- slice_tensors,
- synchronize_rng_states,
- )
- logger = get_logger(__name__)
- # kwargs of the DataLoader in min version 2.0
- _PYTORCH_DATALOADER_KWARGS = {
- "batch_size": 1,
- "shuffle": False,
- "sampler": None,
- "batch_sampler": None,
- "num_workers": 0,
- "collate_fn": None,
- "pin_memory": False,
- "drop_last": False,
- "timeout": 0,
- "worker_init_fn": None,
- "multiprocessing_context": None,
- "generator": None,
- "prefetch_factor": 2,
- "persistent_workers": False,
- "pin_memory_device": "",
- }
- # kwargs added after by version
- _PYTORCH_DATALOADER_ADDITIONAL_KWARGS = {"2.6.0": {"in_order": True}}
- for v, additional_kwargs in _PYTORCH_DATALOADER_ADDITIONAL_KWARGS.items():
- if is_torch_version(">=", v):
- _PYTORCH_DATALOADER_KWARGS.update(additional_kwargs)
- class SeedableRandomSampler(RandomSampler):
- """
- Same as a random sampler, except that in `__iter__` a seed can be used.
- Needed specifically in distributed cases, when the random generator for each GPU needs to start from the same seed
- and be fully reproducible on multiple iterations.
- If a custom `generator` is passed, it will rely on its initial seed as well as the current iteration it is on
- (stored in `self.epoch`).
- """
- def __init__(self, *args, **kwargs):
- data_seed = kwargs.pop("data_seed", None)
- super().__init__(*args, **kwargs)
- self.initial_seed = data_seed if data_seed is not None else torch.random.initial_seed()
- self.epoch = 0
- def __iter__(self):
- if self.generator is None:
- self.generator = torch.Generator(
- device=torch.get_default_device() if hasattr(torch, "get_default_device") else "cpu"
- )
- self.generator.manual_seed(self.initial_seed)
- # Allow `self.epoch` to modify the seed of the generator
- seed = self.epoch + self.initial_seed
- # print("Setting seed at epoch", self.epoch, seed)
- self.generator.manual_seed(seed)
- yield from super().__iter__()
- self.set_epoch(self.epoch + 1)
- def set_epoch(self, epoch: int):
- "Sets the current iteration of the sampler."
- self.epoch = epoch
- class BatchSamplerShard(BatchSampler):
- """
- Wraps a PyTorch `BatchSampler` to generate batches for one of the processes only. Instances of this class will
- always yield a number of batches that is a round multiple of `num_processes` and that all have the same size.
- Depending on the value of the `drop_last` attribute of the batch sampler passed, it will either stop the iteration
- at the first batch that would be too small / not present on all processes or loop with indices from the beginning.
- Args:
- batch_sampler (`torch.utils.data.sampler.BatchSampler`):
- The batch sampler to split in several shards.
- num_processes (`int`, *optional*, defaults to 1):
- The number of processes running concurrently.
- process_index (`int`, *optional*, defaults to 0):
- The index of the current process.
- split_batches (`bool`, *optional*, defaults to `False`):
- Whether the shards should be created by splitting a batch to give a piece of it on each process, or by
- yielding different full batches on each process.
- On two processes with a sampler of `[[0, 1, 2, 3], [4, 5, 6, 7]]`, this will result in:
- - the sampler on process 0 to yield `[0, 1, 2, 3]` and the sampler on process 1 to yield `[4, 5, 6, 7]` if
- this argument is set to `False`.
- - the sampler on process 0 to yield `[0, 1]` then `[4, 5]` and the sampler on process 1 to yield `[2, 3]`
- then `[6, 7]` if this argument is set to `True`.
- even_batches (`bool`, *optional*, defaults to `True`):
- Whether or not to loop back at the beginning of the sampler when the number of samples is not a round
- multiple of (original batch size / number of processes).
- <Tip warning={true}>
- `BatchSampler`s with varying batch sizes are not enabled by default. To enable this behaviour, set `even_batches`
- equal to `False`
- </Tip>"""
- def __init__(
- self,
- batch_sampler: BatchSampler,
- num_processes: int = 1,
- process_index: int = 0,
- split_batches: bool = False,
- even_batches: bool = True,
- ):
- if split_batches and batch_sampler.batch_size % num_processes != 0:
- raise ValueError(
- f"To use `BatchSamplerShard` in `split_batches` mode, the batch size ({batch_sampler.batch_size}) "
- f"needs to be a round multiple of the number of processes ({num_processes})."
- )
- self.batch_sampler = batch_sampler
- self.num_processes = num_processes
- self.process_index = process_index
- self.split_batches = split_batches
- self.even_batches = even_batches
- self.batch_size = getattr(batch_sampler, "batch_size", None)
- self.drop_last = getattr(batch_sampler, "drop_last", False)
- if self.batch_size is None and self.even_batches:
- raise ValueError(
- "You need to use `even_batches=False` when the batch sampler has no batch size. If you "
- "are not calling this method directly, set `accelerator.even_batches=False` instead."
- )
- @property
- def total_length(self):
- return len(self.batch_sampler)
- def __len__(self):
- if self.split_batches:
- # Split batches does not change the length of the batch sampler
- return len(self.batch_sampler)
- if len(self.batch_sampler) % self.num_processes == 0:
- # If the length is a round multiple of the number of processes, it's easy.
- return len(self.batch_sampler) // self.num_processes
- length = len(self.batch_sampler) // self.num_processes
- if self.drop_last:
- # Same if we drop the remainder.
- return length
- elif self.even_batches:
- # When we even batches we always get +1
- return length + 1
- else:
- # Otherwise it depends on the process index.
- return length + 1 if self.process_index < len(self.batch_sampler) % self.num_processes else length
- def __iter__(self):
- return self._iter_with_split() if self.split_batches else self._iter_with_no_split()
- def _iter_with_split(self):
- initial_data = []
- batch_length = self.batch_sampler.batch_size // self.num_processes
- for idx, batch in enumerate(self.batch_sampler):
- if idx == 0:
- initial_data = batch
- if len(batch) == self.batch_size:
- # If the batch is full, we yield the part of it this process is responsible of.
- yield batch[batch_length * self.process_index : batch_length * (self.process_index + 1)]
- # If drop_last is True of the last batch was full, iteration is over, otherwise...
- if not self.drop_last and len(initial_data) > 0 and len(batch) < self.batch_size:
- if not self.even_batches:
- if len(batch) > batch_length * self.process_index:
- yield batch[batch_length * self.process_index : batch_length * (self.process_index + 1)]
- else:
- # For degenerate cases where the dataset has less than num_process * batch_size samples
- while len(initial_data) < self.batch_size:
- initial_data += initial_data
- batch = batch + initial_data
- yield batch[batch_length * self.process_index : batch_length * (self.process_index + 1)]
- def _iter_with_no_split(self):
- initial_data = []
- batch_to_yield = []
- for idx, batch in enumerate(self.batch_sampler):
- # We gather the initial indices in case we need to circle back at the end.
- if not self.drop_last and idx < self.num_processes:
- initial_data += batch
- # We identify the batch to yield but wait until we ar sure every process gets a full batch before actually
- # yielding it.
- if idx % self.num_processes == self.process_index:
- batch_to_yield = batch
- if idx % self.num_processes == self.num_processes - 1 and (
- self.batch_size is None or len(batch) == self.batch_size
- ):
- yield batch_to_yield
- batch_to_yield = []
- # If drop_last is True, iteration is over, otherwise...
- if not self.drop_last and len(initial_data) > 0:
- if not self.even_batches:
- if len(batch_to_yield) > 0:
- yield batch_to_yield
- else:
- # ... we yield the complete batch we had saved before if it has the proper length
- if len(batch_to_yield) == self.batch_size:
- yield batch_to_yield
- # For degenerate cases where the dataset has less than num_process * batch_size samples
- while len(initial_data) < self.num_processes * self.batch_size:
- initial_data += initial_data
- # If the last batch seen was of the proper size, it has been yielded by its process so we move to the next
- if len(batch) == self.batch_size:
- batch = []
- idx += 1
- # Make sure we yield a multiple of self.num_processes batches
- cycle_index = 0
- while idx % self.num_processes != 0 or len(batch) > 0:
- end_index = cycle_index + self.batch_size - len(batch)
- batch += initial_data[cycle_index:end_index]
- if idx % self.num_processes == self.process_index:
- yield batch
- cycle_index = end_index
- batch = []
- idx += 1
- class IterableDatasetShard(IterableDataset):
- """
- Wraps a PyTorch `IterableDataset` to generate samples for one of the processes only. Instances of this class will
- always yield a number of samples that is a round multiple of the actual batch size (depending of the value of
- `split_batches`, this is either `batch_size` or `batch_size x num_processes`). Depending on the value of the
- `drop_last` attribute of the batch sampler passed, it will either stop the iteration at the first batch that would
- be too small or loop with indices from the beginning.
- Args:
- dataset (`torch.utils.data.dataset.IterableDataset`):
- The batch sampler to split in several shards.
- batch_size (`int`, *optional*, defaults to 1):
- The size of the batches per shard (if `split_batches=False`) or the size of the batches (if
- `split_batches=True`).
- drop_last (`bool`, *optional*, defaults to `False`):
- Whether or not to drop the last incomplete batch or complete the last batches by using the samples from the
- beginning.
- num_processes (`int`, *optional*, defaults to 1):
- The number of processes running concurrently.
- process_index (`int`, *optional*, defaults to 0):
- The index of the current process.
- split_batches (`bool`, *optional*, defaults to `False`):
- Whether the shards should be created by splitting a batch to give a piece of it on each process, or by
- yielding different full batches on each process.
- On two processes with an iterable dataset yielding of `[0, 1, 2, 3, 4, 5, 6, 7]`, this will result in:
- - the shard on process 0 to yield `[0, 1, 2, 3]` and the shard on process 1 to yield `[4, 5, 6, 7]` if this
- argument is set to `False`.
- - the shard on process 0 to yield `[0, 1, 4, 5]` and the sampler on process 1 to yield `[2, 3, 6, 7]` if
- this argument is set to `True`.
- """
- def __init__(
- self,
- dataset: IterableDataset,
- batch_size: int = 1,
- drop_last: bool = False,
- num_processes: int = 1,
- process_index: int = 0,
- split_batches: bool = False,
- ):
- if split_batches and batch_size > 1 and batch_size % num_processes != 0:
- raise ValueError(
- f"To use `IterableDatasetShard` in `split_batches` mode, the batch size ({batch_size}) "
- f"needs to be a round multiple of the number of processes ({num_processes})."
- )
- self.dataset: IterableDataset = dataset
- self.batch_size = batch_size
- self.drop_last = drop_last
- self.num_processes = num_processes
- self.process_index = process_index
- self.split_batches = split_batches
- def set_epoch(self, epoch):
- self.epoch = epoch
- if hasattr(self.dataset, "set_epoch"):
- self.dataset.set_epoch(epoch)
- def __len__(self):
- # We will just raise the downstream error if the underlying dataset is not sized
- if self.drop_last:
- return (len(self.dataset) // (self.batch_size * self.num_processes)) * self.batch_size
- else:
- return math.ceil(len(self.dataset) / (self.batch_size * self.num_processes)) * self.batch_size
- def __iter__(self):
- if (
- not hasattr(self.dataset, "set_epoch")
- and hasattr(self.dataset, "generator")
- and isinstance(self.dataset.generator, torch.Generator)
- ):
- self.dataset.generator.manual_seed(self.epoch)
- real_batch_size = self.batch_size if self.split_batches else (self.batch_size * self.num_processes)
- process_batch_size = (self.batch_size // self.num_processes) if self.split_batches else self.batch_size
- process_slice = range(self.process_index * process_batch_size, (self.process_index + 1) * process_batch_size)
- first_batch = None
- current_batch = []
- for element in self.dataset:
- current_batch.append(element)
- # Wait to have a full batch before yielding elements.
- if len(current_batch) == real_batch_size:
- for i in process_slice:
- yield current_batch[i]
- if first_batch is None:
- first_batch = current_batch.copy()
- current_batch = []
- # Finished if drop_last is True, otherwise complete the last batch with elements from the beginning.
- if not self.drop_last and len(current_batch) > 0:
- if first_batch is None:
- first_batch = current_batch.copy()
- while len(current_batch) < real_batch_size:
- current_batch += first_batch
- for i in process_slice:
- yield current_batch[i]
- class DataLoaderStateMixin:
- """
- Mixin class that adds a state to a `DataLoader` to keep track of the status inside the dataloader such as at the
- end of the iteration, the number of items in the dataset in the last batch relative to the batch size, and other
- useful information that might be needed.
- **Available attributes:**
- - **end_of_dataloader** (`bool`) -- Whether at the last iteration or batch
- - **remainder** (`int`) -- The number of items that are remaining in the last batch, relative to the total
- batch size
- <Tip warning={true}>
- Inheriters of this class should ensure that the class creates a `GradientState()` instance, stored in
- `self.gradient_state`.
- </Tip>
- """
- def __init_subclass__(cls, **kwargs):
- cls.end_of_dataloader = False
- cls.remainder = -1
- def reset(self):
- self.end_of_dataloader = False
- self.remainder = -1
- def begin(self):
- "Prepares the gradient state for the current dataloader"
- self.reset()
- with suppress(Exception):
- if not self._drop_last:
- length = getattr(self.dataset, "total_dataset_length", len(self.dataset))
- self.remainder = length % self.total_batch_size
- self.gradient_state._add_dataloader(self)
- def end(self):
- "Cleans up the gradient state after exiting the dataloader"
- self.gradient_state._remove_dataloader(self)
- class DataLoaderAdapter:
- """
- A class which wraps around a PyTorch `DataLoader` (or variants of it) to be used with the `Accelerator`. For
- compatibility reasons, this class inherits from the class it wraps around, so it can be used as a drop-in.
- """
- def __init__(self, dataset, use_stateful_dataloader=False, batch_sampler=None, **kwargs):
- self.use_stateful_dataloader = use_stateful_dataloader
- if is_torchdata_stateful_dataloader_available():
- from torchdata.stateful_dataloader import StatefulDataLoader
- if use_stateful_dataloader and not is_torchdata_stateful_dataloader_available():
- raise ImportError(
- "StatefulDataLoader is not available. Please install torchdata version 0.8.0 or higher to use it."
- )
- if use_stateful_dataloader:
- torchdata_version = version.parse(importlib.metadata.version("torchdata"))
- if (
- "in_order" in kwargs
- and compare_versions(torchdata_version, "<", "0.11")
- and is_torch_version(">=", "2.6.0")
- ):
- kwargs.pop("in_order")
- self.base_dataloader = StatefulDataLoader(dataset, batch_sampler=batch_sampler, **kwargs)
- else:
- self.base_dataloader = DataLoader(dataset, batch_sampler=batch_sampler, **kwargs)
- if hasattr(self.base_dataloader, "state_dict"):
- self.dl_state_dict = self.base_dataloader.state_dict()
- def __getattr__(self, name):
- # Avoid infinite recursion if we try to access a nonexistent base_dataloader attribute.
- if name == "base_dataloader":
- raise AttributeError()
- # Delegate attribute access to the internal dataloader
- return getattr(self.base_dataloader, name)
- def state_dict(self):
- return self.dl_state_dict
- def load_state_dict(self, state_dict):
- self.base_dataloader.load_state_dict(state_dict)
- @property
- def __class__(self):
- """
- In order to maintain backwards compatibility with other code, we need to ensure `isinstance(obj, DataLoader)`
- returns true. This is because some downstream code assumes that the `DataLoader` is the base class of the
- object.
- """
- return self.base_dataloader.__class__
- def __len__(self):
- return len(self.base_dataloader)
- def adjust_state_dict_for_prefetch(self):
- """
- Adjusts the state dict for prefetching. Natively, this will adjust all of the iters yielded keys in
- `self.dl_state_dict` by a factor of `num_processes - 1`, however if a custom correction is needed, this can be
- overridden.
- This should modify `self.dl_state_dict` directly
- """
- # The state dict will be off by a factor of `n-1` batch too many during DDP,
- # so we need to adjust it here
- if PartialState().distributed_type != DistributedType.NO:
- factor = PartialState().num_processes - 1
- if self.dl_state_dict["_sampler_iter_yielded"] > 0:
- self.dl_state_dict["_sampler_iter_yielded"] -= factor
- if self.dl_state_dict["_num_yielded"] > 0:
- self.dl_state_dict["_num_yielded"] -= factor
- if self.dl_state_dict["_index_sampler_state"] is not None:
- if (
- "samples_yielded" in self.dl_state_dict["_index_sampler_state"]
- and self.dl_state_dict["_index_sampler_state"]["samples_yielded"] > 0
- ):
- self.dl_state_dict["_index_sampler_state"]["samples_yielded"] -= self.batch_size * factor
- def _update_state_dict(self):
- # The state_dict of the underlying base_dataloader may be ahead of what is currently being yielded.
- # E.g. the implementation of DataLoaderShard involves having an underlying iterator 1 element ahead of
- # what it wants to yield.
- #
- # _update_state_dict is called to snapshot the state_dict that would properly recover the DataLoaderAdapter.
- if hasattr(self.base_dataloader, "state_dict"):
- self.dl_state_dict = self.base_dataloader.state_dict()
- # Potentially modify the state_dict to adjust for prefetching
- self.adjust_state_dict_for_prefetch()
- # Then tag if we are at the end of the dataloader
- self.dl_state_dict["_iterator_finished"] = self.end_of_dataloader
- class DataLoaderShard(DataLoaderAdapter, DataLoaderStateMixin):
- """
- Subclass of `DataLoaderAdapter` that will deal with device placement and current distributed setup.
- Args:
- dataset (`torch.utils.data.dataset.Dataset`):
- The dataset to use to build this dataloader.
- device (`torch.device`, *optional*):
- If passed, the device to put all batches on.
- rng_types (list of `str` or [`~utils.RNGType`]):
- The list of random number generators to synchronize at the beginning of each iteration. Should be one or
- several of:
- - `"torch"`: the base torch random number generator
- - `"cuda"`: the CUDA random number generator (GPU only)
- - `"xla"`: the XLA random number generator (TPU only)
- - `"generator"`: an optional `torch.Generator`
- synchronized_generator (`torch.Generator`, *optional*):
- A random number generator to keep synchronized across processes.
- skip_batches (`int`, *optional*, defaults to 0):
- The number of batches to skip at the beginning.
- use_stateful_dataloader (`bool`, *optional*, defaults to `False`):
- Whether to have this class adapt `StatefulDataLoader` from `torchdata` instead of the regular `DataLoader`.
- **kwargs (additional keyword arguments, *optional*):
- All other keyword arguments to pass to the regular `DataLoader` initialization.
- **Available attributes:**
- - **total_batch_size** (`int`) -- Total batch size of the dataloader across all processes.
- Equal to the original batch size when `split_batches=True`; otherwise the original batch size * the total
- number of processes
- - **total_dataset_length** (`int`) -- Total length of the inner dataset across all processes.
- """
- def __init__(
- self,
- dataset,
- device=None,
- rng_types=None,
- synchronized_generator=None,
- skip_batches=0,
- use_stateful_dataloader=False,
- _drop_last: bool = False,
- _non_blocking: bool = False,
- torch_device_mesh=None,
- **kwargs,
- ):
- super().__init__(dataset, use_stateful_dataloader=use_stateful_dataloader, **kwargs)
- self.device = device
- self.rng_types = rng_types
- self.synchronized_generator = synchronized_generator
- self.skip_batches = skip_batches
- self.gradient_state = GradientState()
- self._drop_last = _drop_last
- self._non_blocking = _non_blocking
- self.iteration = 0
- def __iter__(self):
- if self.rng_types is not None:
- synchronize_rng_states(self.rng_types, self.synchronized_generator)
- self.begin()
- self.set_epoch(self.iteration)
- dataloader_iter = self.base_dataloader.__iter__()
- # We iterate one batch ahead to check when we are at the end
- try:
- current_batch = next(dataloader_iter)
- except StopIteration:
- self.end()
- return
- batch_index = 0
- while True:
- try:
- # But we still move it to the device so it is done before `StopIteration` is reached
- if self.device is not None:
- current_batch = send_to_device(current_batch, self.device, non_blocking=self._non_blocking)
- self._update_state_dict()
- next_batch = next(dataloader_iter)
- if batch_index >= self.skip_batches:
- yield current_batch
- batch_index += 1
- current_batch = next_batch
- except StopIteration:
- self.end_of_dataloader = True
- self._update_state_dict()
- if batch_index >= self.skip_batches:
- yield current_batch
- break
- self.iteration += 1
- self.end()
- def __reduce__(self):
- """
- Define the `__reduce__` method to ensure a `DataLoaderShard` can be pickled and unpickled. This needs to be
- explicitly defined since default pickling behavior is broken by `DataLoaderAdapter` messing with its
- `__class__` member.
- """
- args = super().__reduce__()
- return (DataLoaderShard, *args[1:])
- def set_epoch(self, epoch: int):
- # In case it is manually passed in, the user can set it to what they like
- if self.iteration != epoch:
- self.iteration = epoch
- if hasattr(self.batch_sampler, "set_epoch"):
- self.batch_sampler.set_epoch(epoch)
- if hasattr(self.batch_sampler, "sampler") and hasattr(self.batch_sampler.sampler, "set_epoch"):
- self.batch_sampler.sampler.set_epoch(epoch)
- if (
- hasattr(self.batch_sampler, "batch_sampler")
- and hasattr(self.batch_sampler.batch_sampler, "sampler")
- and hasattr(self.batch_sampler.batch_sampler.sampler, "set_epoch")
- ):
- self.batch_sampler.batch_sampler.sampler.set_epoch(epoch)
- # We support if a custom `Dataset` implementation has `set_epoch`
- # or in general HF datasets `Datasets`
- elif hasattr(self.dataset, "set_epoch"):
- self.dataset.set_epoch(epoch)
- @property
- def total_batch_size(self):
- batch_sampler = self.sampler if isinstance(self.sampler, BatchSampler) else self.batch_sampler
- return (
- batch_sampler.batch_size
- if getattr(batch_sampler, "split_batches", False)
- else (batch_sampler.batch_size * getattr(batch_sampler, "num_processes", 1))
- )
- @property
- def total_dataset_length(self):
- if hasattr(self.dataset, "total_length"):
- return self.dataset.total_length
- else:
- return len(self.dataset)
- def get_sampler(self):
- return get_sampler(self)
- def set_sampler(self, sampler):
- sampler_is_batch_sampler = isinstance(self.sampler, BatchSampler)
- if sampler_is_batch_sampler:
- self.sampler.sampler = sampler
- else:
- self.batch_sampler.sampler = sampler
- if hasattr(self.batch_sampler, "batch_sampler"):
- self.batch_sampler.batch_sampler.sampler = sampler
- if is_torch_xla_available():
- import torch_xla.distributed.parallel_loader as xpl
- class MpDeviceLoaderWrapper(xpl.MpDeviceLoader):
- """
- Wrapper for the xpl.MpDeviceLoader class that knows the total batch size.
- XLA preloading threads will all call DataLoaderShard's __iter__(). Remove rng_types from DataLoaderShard to
- prevent it from using the XLA device in the preloading threads, and synchronize the RNG once from the main
- thread only.
- **Available attributes:**
- - **total_batch_size** (`int`) -- Total batch size of the dataloader across all processes.
- Equal to the original batch size when `split_batches=True`; otherwise the original batch size * the total
- number of processes
- - **total_dataset_length** (`int`) -- Total length of the inner dataset across all processes.
- """
- def __init__(self, dataloader: DataLoaderShard, device: torch.device):
- super().__init__(dataloader, device)
- self._rng_types = self._loader.rng_types
- self._loader.rng_types = None
- self.device = device
- def __iter__(self):
- if self._rng_types is not None:
- synchronize_rng_states(self._rng_types, self._loader.synchronized_generator)
- return super().__iter__()
- def set_epoch(self, epoch: int):
- if hasattr(self.dataloader, "set_epoch"):
- self.dataloader.set_epoch(epoch)
- @property
- def total_batch_size(self):
- return self._loader.total_batch_size
- @property
- def total_dataset_length(self):
- return self._loader.total_dataset_length
- @property
- def batch_sampler(self):
- return self._loader.batch_sampler
- @property
- def dataloader(self):
- return self._loader
- class DataLoaderDispatcher(DataLoaderAdapter, DataLoaderStateMixin):
- """
- Subclass of `DataLoaderAdapter` that will iterate and preprocess on process 0 only, then dispatch on each process
- their part of the batch.
- Args:
- split_batches (`bool`, *optional*, defaults to `False`):
- Whether the resulting `DataLoader` should split the batches of the original data loader across devices or
- yield full batches (in which case it will yield batches starting at the `process_index`-th and advancing of
- `num_processes` batches at each iteration). Another way to see this is that the observed batch size will be
- the same as the initial `dataloader` if this option is set to `True`, the batch size of the initial
- `dataloader` multiplied by `num_processes` otherwise. Setting this option to `True` requires that the batch
- size of the `dataloader` is a round multiple of `batch_size`.
- skip_batches (`int`, *optional*, defaults to 0):
- The number of batches to skip at the beginning of an iteration.
- use_stateful_dataloader (`bool`, *optional*, defaults to `False`):
- Whether to have this class adapt `StatefulDataLoader` from `torchdata` instead of the regular `DataLoader`.
- **Available attributes:**
- - **total_batch_size** (`int`) -- Total batch size of the dataloader across all processes.
- Equal to the original batch size when `split_batches=True`; otherwise the original batch size * the total
- number of processes
- - **total_dataset_length** (`int`) -- Total length of the inner dataset across all processes.
- """
- def __init__(
- self,
- dataset,
- split_batches: bool = False,
- skip_batches=0,
- use_stateful_dataloader=False,
- _drop_last: bool = False,
- _non_blocking: bool = False,
- slice_fn=None,
- torch_device_mesh=None,
- **kwargs,
- ):
- shuffle = False
- from torch.utils.data.datapipes.iter.combinatorics import ShufflerIterDataPipe
- # We need to save the shuffling state of the DataPipe
- if isinstance(dataset, ShufflerIterDataPipe):
- shuffle = dataset._shuffle_enabled
- super().__init__(dataset, use_stateful_dataloader=use_stateful_dataloader, **kwargs)
- self.split_batches = split_batches
- if shuffle:
- torch.utils.data.graph_settings.apply_shuffle_settings(dataset, shuffle=shuffle)
- self.gradient_state = GradientState()
- self.state = PartialState()
- self._drop_last = _drop_last
- self._non_blocking = _non_blocking
- self.skip_batches = skip_batches
- self.torch_device_mesh = torch_device_mesh
- self.slice_fn = slice_tensors if slice_fn is None else slice_fn
- self.iteration = 0
- # if a device mesh is provided extract each dimension (dp, fsdp, tp)
- # device mesh may hold any number of dimensions, however,
- # below code is for targeted support for dp, fsdp and tp
- # device mesh will be used only if there is tp involved
- # or any multi-dimensional parallelism involving tp
- # (dp, tp) (fsdp, tp) (dp, fsdp, tp)
- # otherwise the default behaviour not using device mesh should be sufficient
- # since multi dimensional parallelism devoid of tp would anyway need
- # different batches for each process irrespective of dp or fsdp
- self.submesh_tp = None
- self.submesh_dp = None
- self.submesh_fsdp = None
- if self.torch_device_mesh and "tp" in self.torch_device_mesh.mesh_dim_names:
- self.submesh_tp = self.torch_device_mesh["tp"]
- if "dp" in self.torch_device_mesh.mesh_dim_names:
- self.submesh_dp = self.torch_device_mesh["dp"]
- if "fsdp" in self.torch_device_mesh.mesh_dim_names:
- self.submesh_fsdp = self.torch_device_mesh["fsdp"]
- if self.submesh_tp and (self.submesh_dp or self.submesh_fsdp):
- raise ValueError("TP + (DP/FSDP) is not yet supported in dispatch mode")
- def _fetch_batches(self, iterator):
- batches, batch = None, None
- # On process 0, we gather the batch to dispatch.
- if self.state.process_index == 0:
- # Procedure to support TP only is simpler
- # since we want to dispatch the same batch of samples across all ranks
- # this removes complexity of handling multiple tp rank groups when TP + DP
- # combination is involved.
- try:
- # for TP case avoid using split_batches
- # since it would mean that the dataloader should be spilling out
- # duplicates of batches.
- if self.split_batches:
- # One batch of the main iterator is dispatched and split.
- if self.submesh_tp:
- logger.warning(
- "Use of split_batches for TP would need the dataloader to produce duplicate batches,"
- "otherwise, use dispatch_batches=True instead."
- )
- self._update_state_dict()
- batch = next(iterator)
- else:
- # num_processes batches of the main iterator are concatenated then dispatched and split.
- # We add the batches one by one so we have the remainder available when drop_last=False.
- batches = []
- if self.submesh_tp:
- # when tp, extract single batch and then replicate
- self._update_state_dict()
- batch = next(iterator)
- batches = [batch] * self.state.num_processes
- else:
- for _ in range(self.state.num_processes):
- self._update_state_dict()
- batches.append(next(iterator))
- try:
- batch = concatenate(batches, dim=0)
- except RuntimeError as e:
- raise RuntimeError(
- "You can't use batches of different size with `dispatch_batches=True` or when using an `IterableDataset`."
- "either pass `dispatch_batches=False` and have each process fetch its own batch "
- " or pass `split_batches=True`. By doing so, the main process will fetch a full batch and "
- "slice it into `num_processes` batches for each process."
- ) from e
- # In both cases, we need to get the structure of the batch that we will broadcast on other
- # processes to initialize the tensors with the right shape.
- # data_structure, stop_iteration
- batch_info = [get_data_structure(batch), False]
- except StopIteration:
- batch_info = [None, True]
- else:
- batch_info = [None, self._stop_iteration]
- # This is inplace, so after this instruction, every process has the same `batch_info` as process 0.
- broadcast_object_list(batch_info)
- self._stop_iteration = batch_info[1]
- if self._stop_iteration:
- # If drop_last is False and split_batches is False, we may have a remainder to take care of.
- if not self.split_batches and not self._drop_last:
- if self.state.process_index == 0 and len(batches) > 0:
- batch = concatenate(batches, dim=0)
- batch_info = [get_data_structure(batch), False]
- else:
- batch_info = [None, True]
- broadcast_object_list(batch_info)
- return batch, batch_info
- def __iter__(self):
- self.begin()
- self.set_epoch(self.iteration)
- main_iterator = None
- if is_torch_version(">=", "2.0.1"):
- # NOTE PyTorch DataLoader adds forward compatibilities for DataPipes, which broadcasts
- # shared seed to all dist processes. Thus, we need to create iterator for all dist processes.
- # But, we only iterate through the DataLoader on process 0.
- main_iterator = self.base_dataloader.__iter__()
- elif self.state.process_index == 0:
- main_iterator = self.base_dataloader.__iter__()
- stop_iteration = False
- self._stop_iteration = False
- first_batch = None
- next_batch, next_batch_info = self._fetch_batches(main_iterator)
- batch_index = 0
- while not stop_iteration:
- batch, batch_info = next_batch, next_batch_info
- if self.state.process_index != 0:
- # Initialize tensors on other processes than process 0.
- batch = initialize_tensors(batch_info[0])
- batch = send_to_device(batch, self.state.device, non_blocking=self._non_blocking)
- # Broadcast the batch before splitting it.
- batch = broadcast(batch, from_process=0)
- if not self._drop_last and first_batch is None:
- # We keep at least num processes elements of the first batch to be able to complete the last batch
- first_batch = self.slice_fn(
- batch,
- slice(0, self.state.num_processes),
- process_index=self.state.process_index,
- num_processes=self.state.num_processes,
- )
- if batch is None:
- raise ValueError(
- f"Batch does not contain any data (`{batch}`). At the end of all iterable data available before expected stop iteration."
- )
- observed_batch_size = find_batch_size(batch)
- batch_size = observed_batch_size // self.state.num_processes
- stop_iteration = self._stop_iteration
- if not stop_iteration:
- # We may still be at the end of the dataloader without knowing it yet: if there is nothing left in
- # the dataloader since the number of batches is a round multiple of the number of processes.
- next_batch, next_batch_info = self._fetch_batches(main_iterator)
- # next_batch_info[0] is None when there are no more batches, otherwise we still need to process them.
- if self._stop_iteration and next_batch_info[0] is None:
- stop_iteration = True
- if not self._drop_last and stop_iteration and observed_batch_size % self.state.num_processes != 0:
- # If the last batch is not complete, let's add the first batch to it.
- batch = concatenate([batch, first_batch], dim=0)
- # Batch size computation above is wrong, it's off by 1 so we fix it.
- batch_size += 1
- data_slice = slice(self.state.process_index * batch_size, (self.state.process_index + 1) * batch_size)
- batch = self.slice_fn(
- batch,
- data_slice,
- process_index=self.state.process_index,
- num_processes=self.state.num_processes,
- )
- if stop_iteration:
- self.end_of_dataloader = True
- self._update_state_dict()
- self.remainder = observed_batch_size
- if batch_index >= self.skip_batches:
- yield batch
- batch_index += 1
- self.iteration += 1
- self.end()
- def set_epoch(self, epoch: int):
- # In case it is manually passed in, the user can set it to what they like
- if self.iteration != epoch:
- self.iteration = epoch
- if hasattr(self.batch_sampler, "sampler") and hasattr(self.batch_sampler.sampler, "set_epoch"):
- self.batch_sampler.sampler.set_epoch(epoch)
- elif hasattr(self.dataset, "set_epoch"):
- self.dataset.set_epoch(epoch)
- def __len__(self):
- whole_length = len(self.base_dataloader)
- if self.split_batches:
- return whole_length
- elif self._drop_last:
- return whole_length // self.state.num_processes
- else:
- return math.ceil(whole_length / self.state.num_processes)
- def __reduce__(self):
- """
- Define the `__reduce__` method to ensure a `DataLoaderDispatcher` can be pickled and unpickled. This needs to
- be explicitly defined since default pickling behavior is broken by `DataLoaderAdapter` messing with its
- `__class__` member.
- """
- args = super().__reduce__()
- return (DataLoaderDispatcher, *args[1:])
- @property
- def total_batch_size(self):
- return (
- self.dataset.batch_size if self.split_batches else (self.dataset.batch_size * self.dataset.num_processes)
- )
- @property
- def total_dataset_length(self):
- return len(self.dataset)
- def get_sampler(self):
- return get_sampler(self)
- def set_sampler(self, sampler):
- sampler_is_batch_sampler = isinstance(self.sampler, BatchSampler)
- if sampler_is_batch_sampler:
- self.sampler.sampler = sampler
- else:
- self.batch_sampler.sampler = sampler
- if hasattr(self.batch_sampler, "batch_sampler"):
- self.batch_sampler.batch_sampler.sampler = sampler
- def get_sampler(dataloader):
- """
- Get the sampler associated to the dataloader
- Args:
- dataloader (`torch.utils.data.dataloader.DataLoader`):
- The data loader to split across several devices.
- Returns:
- `torch.utils.data.Sampler`: The sampler associated to the dataloader
- """
- sampler_is_batch_sampler = isinstance(dataloader.sampler, BatchSampler)
- if sampler_is_batch_sampler:
- sampler = getattr(dataloader.sampler, "sampler", None)
- else:
- sampler = getattr(dataloader.batch_sampler, "sampler", None)
- return sampler
- def prepare_data_loader(
- dataloader: DataLoader,
- device: Optional[torch.device] = None,
- num_processes: Optional[int] = None,
- process_index: Optional[int] = None,
- split_batches: bool = False,
- put_on_device: bool = False,
- rng_types: Optional[list[Union[str, RNGType]]] = None,
- dispatch_batches: Optional[bool] = None,
- even_batches: bool = True,
- slice_fn_for_dispatch: Optional[Callable] = None,
- use_seedable_sampler: bool = False,
- data_seed: Optional[int] = None,
- non_blocking: bool = False,
- use_stateful_dataloader: bool = False,
- torch_device_mesh=None,
- ) -> DataLoader:
- """
- Wraps a PyTorch `DataLoader` to generate batches for one of the processes only.
- Depending on the value of the `drop_last` attribute of the `dataloader` passed, it will either stop the iteration
- at the first batch that would be too small / not present on all processes or loop with indices from the beginning.
- Args:
- dataloader (`torch.utils.data.dataloader.DataLoader`):
- The data loader to split across several devices.
- device (`torch.device`):
- The target device for the returned `DataLoader`.
- num_processes (`int`, *optional*):
- The number of processes running concurrently. Will default to the value given by [`~state.PartialState`].
- process_index (`int`, *optional*):
- The index of the current process. Will default to the value given by [`~state.PartialState`].
- split_batches (`bool`, *optional*, defaults to `False`):
- Whether the resulting `DataLoader` should split the batches of the original data loader across devices or
- yield full batches (in which case it will yield batches starting at the `process_index`-th and advancing of
- `num_processes` batches at each iteration).
- Another way to see this is that the observed batch size will be the same as the initial `dataloader` if
- this option is set to `True`, the batch size of the initial `dataloader` multiplied by `num_processes`
- otherwise.
- Setting this option to `True` requires that the batch size of the `dataloader` is a round multiple of
- `batch_size`.
- put_on_device (`bool`, *optional*, defaults to `False`):
- Whether or not to put the batches on `device` (only works if the batches are nested list, tuples or
- dictionaries of tensors).
- rng_types (list of `str` or [`~utils.RNGType`]):
- The list of random number generators to synchronize at the beginning of each iteration. Should be one or
- several of:
- - `"torch"`: the base torch random number generator
- - `"cuda"`: the CUDA random number generator (GPU only)
- - `"xla"`: the XLA random number generator (TPU only)
- - `"generator"`: the `torch.Generator` of the sampler (or batch sampler if there is no sampler in your
- dataloader) or of the iterable dataset (if it exists) if the underlying dataset is of that type.
- dispatch_batches (`bool`, *optional*):
- If set to `True`, the dataloader prepared is only iterated through on the main process and then the batches
- are split and broadcast to each process. Will default to `True` when the underlying dataset is an
- `IterableDataset`, `False` otherwise.
- even_batches (`bool`, *optional*, defaults to `True`):
- If set to `True`, in cases where the total batch size across all processes does not exactly divide the
- dataset, samples at the start of the dataset will be duplicated so the batch can be divided equally among
- all workers.
- slice_fn_for_dispatch (`Callable`, *optional*`):
- If passed, this function will be used to slice tensors across `num_processes`. Will default to
- [`~utils.slice_tensors`]. This argument is used only when `dispatch_batches` is set to `True` and will be
- ignored otherwise.
- use_seedable_sampler (`bool`, *optional*, defaults to `False`):
- Whether to use the [`~data_loader.SeedableRandomSampler`] instead of a `RandomSampler` for better
- reproducibility. Comes at a cost of potentially different performances due to different shuffling
- algorithms but ensures results will be the *exact* same. Should be paired with `set_seed()` at every
- `self.set_epoch`
- data_seed (`int`, *optional*, defaults to `None`):
- The seed to use for the underlying generator when using `use_seedable_sampler`. If `None`, the generator
- will use the current default seed from torch.
- non_blocking (`bool`, *optional*, defaults to `False`):
- If set to `True`, dataloader will utilize non-blocking host-to-device transfers. If the dataloader has
- `pin_memory` set to `True`, this will help to increase overlap between data transfer and computations.
- use_stateful_dataloader (`bool`, *optional*, defaults to `False`):
- "If set to true, the dataloader prepared by the Accelerator will be backed by "
- "[torchdata.StatefulDataLoader](https://github.com/pytorch/data/tree/main/torchdata/stateful_dataloader).
- This requires `torchdata` version 0.8.0 or higher that supports StatefulDataLoader to be installed."
- torch_device_mesh (`torch.distributed.DeviceMesh`, *optional*, defaults to `None`):
- PyTorch device mesh.
- Returns:
- `torch.utils.data.dataloader.DataLoader`: A new data loader that will yield the portion of the batches
- <Tip warning={true}>
- `BatchSampler`s with varying batch sizes are not enabled by default. To enable this behaviour, set `even_batches`
- equal to `False`
- </Tip>
- """
- if dispatch_batches is None:
- if not put_on_device:
- dispatch_batches = False
- else:
- dispatch_batches = isinstance(dataloader.dataset, IterableDataset)
- if dispatch_batches and not put_on_device:
- raise ValueError("Using `dispatch_batches=True` requires `put_on_device=True`.")
- # Grab defaults from PartialState
- state = PartialState()
- if num_processes is None:
- num_processes = state.num_processes
- if process_index is None:
- process_index = state.process_index
- if torch_device_mesh:
- if state.distributed_type == DistributedType.DEEPSPEED:
- # In DeepSpeed, the optimizer sharing level in DP is determined by the config file.
- # Only considers "dp" and "tp".
- # Given a device mesh (dp, tp) = (2, 3):
- # - From the data parallel perspective, ranks should be structured as: 0 0 0 1 1 1
- # - Processes with the same DP rank will receive the same batch.
- submesh_tp_size = 1
- if "tp" in torch_device_mesh.mesh_dim_names:
- submesh_tp_size = torch_device_mesh["tp"].size()
- process_index = process_index // submesh_tp_size
- num_processes = num_processes // submesh_tp_size
- else:
- # when device mesh is used, specifically with TP
- # then there is need to update process_index and num_processes
- # to bring in the effect of generating same batch across TP ranks
- # and different batch across FSDP and DP ranks.
- # Example:
- # if device mesh is (dp,fsdp,tp) = (2, 2, 3)
- # ranks would range from 0...11
- # from data angle ranks should look like 0 0 0 1 1 1 2 2 2 3 3 3
- # processes with same ranks/ids would receive the same batch
- # for CP the same as TP applies
- submesh_fsdp_size = 1
- submesh_dp_size = 1
- submesh_tp_size = 1
- submesh_cp_size = 1
- if "tp" in torch_device_mesh.mesh_dim_names:
- submesh_tp_size = torch_device_mesh["tp"].size()
- if "cp" in torch_device_mesh.mesh_dim_names:
- submesh_cp_size = torch_device_mesh["cp"].size()
- if "dp_replicate" in torch_device_mesh.mesh_dim_names:
- submesh_dp_size = torch_device_mesh["dp_replicate"].size()
- if "dp_shard" in torch_device_mesh.mesh_dim_names:
- submesh_fsdp_size = torch_device_mesh["dp_shard"].size()
- process_index = process_index // (submesh_tp_size * submesh_cp_size)
- num_processes = submesh_fsdp_size * submesh_dp_size
- # Sanity check
- if split_batches:
- if dataloader.batch_size is not None:
- batch_size_for_check = dataloader.batch_size
- else:
- # For custom batch_sampler
- if hasattr(dataloader.batch_sampler, "batch_size"):
- batch_size_for_check = dataloader.batch_sampler.batch_size
- else:
- raise ValueError(
- "In order to use `split_batches==True` you must have a `batch_size` attribute either in the passed "
- "`dataloader` or `dataloader.batch_sampler` objects, and it has to return a natural number. "
- "Your `dataloader.batch_size` is None and `dataloader.batch_sampler` "
- f"(`{type(dataloader.batch_sampler)}`) does not have the `batch_size` attribute set."
- )
- if batch_size_for_check > 1 and batch_size_for_check % num_processes != 0:
- raise ValueError(
- f"To use a `DataLoader` in `split_batches` mode, the batch size ({dataloader.batch_size}) "
- f"needs to be a round multiple of the number of processes ({num_processes})."
- )
- new_dataset = dataloader.dataset
- # Iterable dataset doesn't like batch_sampler, but data_loader creates a default one for it
- new_batch_sampler = dataloader.batch_sampler if not isinstance(new_dataset, IterableDataset) else None
- sampler_is_batch_sampler = isinstance(dataloader.sampler, BatchSampler)
- synchronized_generator = None
- sampler = get_sampler(dataloader)
- if isinstance(sampler, RandomSampler) and use_seedable_sampler:
- # When iterating through the dataloader during distributed processes
- # we want to ensure that on each process we are iterating through the same
- # samples in the same order if a seed is set. This requires a tweak
- # to the `torch.utils.data.RandomSampler` class (if used).
- sampler = SeedableRandomSampler(
- data_source=sampler.data_source,
- replacement=sampler.replacement,
- num_samples=sampler._num_samples,
- generator=getattr(
- sampler,
- "generator",
- torch.Generator(device=torch.get_default_device() if hasattr(torch, "get_default_device") else "cpu"),
- ),
- data_seed=data_seed,
- )
- if isinstance(dataloader.sampler, RandomSampler) and state.distributed_type == DistributedType.XLA:
- # isinstance(dataloader.sampler, RandomSampler) indicates the original dataloader has `shuffle` enabled.
- generator = torch.Generator(
- device=torch.get_default_device() if hasattr(torch, "get_default_device") else "cpu"
- )
- seed = int(torch.empty((), dtype=torch.int64).random_().item())
- generator.manual_seed(seed)
- dataloader.generator = generator
- dataloader.sampler.generator = generator
- # No change if no multiprocess
- if (num_processes != 1 or state.distributed_type == DistributedType.MEGATRON_LM) and not dispatch_batches:
- if is_datasets_available():
- from datasets import IterableDataset as DatasetsIterableDataset
- if (
- is_datasets_available()
- and isinstance(new_dataset, DatasetsIterableDataset)
- and not split_batches
- and new_dataset.n_shards > num_processes
- ):
- new_dataset = new_dataset.shard(num_shards=num_processes, index=process_index)
- elif isinstance(new_dataset, IterableDataset):
- if getattr(dataloader.dataset, "generator", None) is not None:
- synchronized_generator = dataloader.dataset.generator
- new_dataset = IterableDatasetShard(
- new_dataset,
- batch_size=dataloader.batch_size,
- drop_last=dataloader.drop_last,
- num_processes=num_processes,
- process_index=process_index,
- split_batches=split_batches,
- )
- else:
- if not use_seedable_sampler and hasattr(sampler, "generator"):
- if sampler.generator is None:
- sampler.generator = torch.Generator(
- device=torch.get_default_device() if hasattr(torch, "get_default_device") else "cpu"
- )
- seed = int(torch.empty((), dtype=torch.int64).random_().item())
- sampler.generator.manual_seed(seed)
- synchronized_generator = sampler.generator
- batch_sampler = dataloader.sampler if sampler_is_batch_sampler else dataloader.batch_sampler
- new_batch_sampler = BatchSamplerShard(
- batch_sampler,
- num_processes=num_processes,
- process_index=process_index,
- split_batches=split_batches,
- even_batches=even_batches,
- )
- # We ignore all of those since they are all dealt with by our new_batch_sampler
- ignore_kwargs = [
- "batch_size",
- "shuffle",
- "sampler",
- "batch_sampler",
- "drop_last",
- ]
- if rng_types is not None and synchronized_generator is None and "generator" in rng_types:
- rng_types.remove("generator")
- kwargs = {
- k: getattr(dataloader, k, _PYTORCH_DATALOADER_KWARGS[k])
- for k in _PYTORCH_DATALOADER_KWARGS
- if k not in ignore_kwargs
- }
- # Need to provide batch_size as batch_sampler is None for Iterable dataset
- if new_batch_sampler is None:
- kwargs["drop_last"] = dataloader.drop_last
- kwargs["batch_size"] = (
- dataloader.batch_size // num_processes if split_batches and not dispatch_batches else dataloader.batch_size
- )
- if dispatch_batches:
- kwargs.pop("generator")
- dataloader = DataLoaderDispatcher(
- new_dataset,
- split_batches=split_batches,
- batch_sampler=new_batch_sampler,
- _drop_last=dataloader.drop_last,
- _non_blocking=non_blocking,
- slice_fn=slice_fn_for_dispatch,
- use_stateful_dataloader=use_stateful_dataloader,
- torch_device_mesh=torch_device_mesh,
- **kwargs,
- )
- elif sampler_is_batch_sampler:
- dataloader = DataLoaderShard(
- new_dataset,
- device=device if put_on_device and state.distributed_type != DistributedType.XLA else None,
- sampler=new_batch_sampler,
- batch_size=dataloader.batch_size,
- rng_types=rng_types,
- _drop_last=dataloader.drop_last,
- _non_blocking=non_blocking,
- synchronized_generator=synchronized_generator,
- use_stateful_dataloader=use_stateful_dataloader,
- **kwargs,
- )
- else:
- dataloader = DataLoaderShard(
- new_dataset,
- device=device if put_on_device and state.distributed_type != DistributedType.XLA else None,
- batch_sampler=new_batch_sampler,
- rng_types=rng_types,
- synchronized_generator=synchronized_generator,
- _drop_last=dataloader.drop_last,
- _non_blocking=non_blocking,
- use_stateful_dataloader=use_stateful_dataloader,
- **kwargs,
- )
- if isinstance(sampler, SeedableRandomSampler) and use_seedable_sampler:
- dataloader.set_sampler(sampler)
- if state.distributed_type == DistributedType.XLA:
- return MpDeviceLoaderWrapper(dataloader, device)
- return dataloader
- class SkipBatchSampler(BatchSampler):
- """
- A `torch.utils.data.BatchSampler` that skips the first `n` batches of another `torch.utils.data.BatchSampler`.
- Should not be used if the original dataloader is a `StatefulDataLoader`.
- """
- def __init__(self, batch_sampler, skip_batches=0):
- self.batch_sampler = batch_sampler
- self.skip_batches = skip_batches
- def __iter__(self):
- for index, samples in enumerate(self.batch_sampler):
- if index >= self.skip_batches:
- yield samples
- @property
- def total_length(self):
- return len(self.batch_sampler)
- def __len__(self):
- return len(self.batch_sampler) - self.skip_batches
- class SkipDataLoader(DataLoaderAdapter, DataLoaderStateMixin):
- """
- Subclass of a PyTorch `DataLoader` that will skip the first batches. Generally it's preferable to use
- `skip_first_batches`/`torchdata.StatefulDataLoader` instead of this class.
- Args:
- dataset (`torch.utils.data.dataset.Dataset`):
- The dataset to use to build this dataloader.
- skip_batches (`int`, *optional*, defaults to 0):
- The number of batches to skip at the beginning.
- kwargs:
- All other keyword arguments to pass to the regular `DataLoader` initialization.
- """
- def __init__(self, dataset, skip_batches=0, use_stateful_dataloader=False, **kwargs):
- super().__init__(dataset, use_stateful_dataloader=use_stateful_dataloader, **kwargs)
- self.skip_batches = skip_batches
- self.gradient_state = GradientState()
- def __iter__(self):
- self.begin()
- for index, batch in enumerate(self.base_dataloader.__iter__()):
- if index >= self.skip_batches:
- self._update_state_dict()
- yield batch
- self.end()
- def __len__(self):
- return len(self.base_dataloader) - self.skip_batches
- def __reduce__(self):
- """
- Define the `__reduce__` method to ensure a `SkipDataLoader` can be pickled and unpickled. This needs to be
- explicitly defined since default pickling behavior is broken by `DataLoaderAdapter` messing with its
- `__class__` member.
- """
- args = super().__reduce__()
- return (SkipDataLoader, *args[1:])
- def skip_first_batches(dataloader, num_batches=0):
- """
- Creates a `torch.utils.data.DataLoader` that will efficiently skip the first `num_batches`. Should not be used if
- the original dataloader is a `StatefulDataLoader`.
- """
- state = PartialState()
- if state.distributed_type == DistributedType.XLA:
- device = dataloader.device
- dataloader = dataloader.dataloader
- dataset = dataloader.dataset
- sampler_is_batch_sampler = False
- if isinstance(dataset, IterableDataset):
- new_batch_sampler = None
- else:
- sampler_is_batch_sampler = isinstance(dataloader.sampler, BatchSampler)
- batch_sampler = dataloader.sampler if sampler_is_batch_sampler else dataloader.batch_sampler
- new_batch_sampler = SkipBatchSampler(batch_sampler, skip_batches=num_batches)
- # We ignore all of those since they are all dealt with by our new_batch_sampler
- ignore_kwargs = [
- "batch_size",
- "shuffle",
- "sampler",
- "batch_sampler",
- "drop_last",
- ]
- kwargs = {
- k: getattr(dataloader, k, _PYTORCH_DATALOADER_KWARGS[k])
- for k in _PYTORCH_DATALOADER_KWARGS
- if k not in ignore_kwargs
- }
- # Need to provide batch_size as batch_sampler is None for Iterable dataset
- if new_batch_sampler is None:
- kwargs["drop_last"] = dataloader.drop_last
- kwargs["batch_size"] = dataloader.batch_size
- if isinstance(dataloader, DataLoaderDispatcher):
- if new_batch_sampler is None:
- # Need to manually skip batches in the dataloader
- kwargs["skip_batches"] = num_batches
- dataloader = DataLoaderDispatcher(
- dataset,
- split_batches=dataloader.split_batches,
- batch_sampler=new_batch_sampler,
- _drop_last=dataloader._drop_last,
- **kwargs,
- )
- elif isinstance(dataloader, DataLoaderShard):
- if new_batch_sampler is None:
- # Need to manually skip batches in the dataloader
- kwargs["skip_batches"] = num_batches
- elif sampler_is_batch_sampler:
- kwargs["sampler"] = new_batch_sampler
- kwargs["batch_size"] = dataloader.batch_size
- else:
- kwargs["batch_sampler"] = new_batch_sampler
- dataloader = DataLoaderShard(
- dataset,
- device=dataloader.device,
- rng_types=dataloader.rng_types,
- synchronized_generator=dataloader.synchronized_generator,
- **kwargs,
- )
- else:
- if new_batch_sampler is None:
- # Need to manually skip batches in the dataloader
- dataloader = SkipDataLoader(dataset, skip_batches=num_batches, **kwargs)
- else:
- dataloader = DataLoader(dataset, batch_sampler=new_batch_sampler, **kwargs)
- if state.distributed_type == DistributedType.XLA:
- dataloader = MpDeviceLoaderWrapper(dataloader, device)
- return dataloader
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