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| # modified from https://github.com/feng-yufei/shared_debugging_code/blob/main/bucketsampler.py | |
| import itertools | |
| import math | |
| import random | |
| from random import shuffle | |
| from typing import Iterator | |
| from typing import Optional | |
| from typing import TypeVar | |
| import torch | |
| import torch.distributed as dist | |
| from torch.utils.data import Dataset | |
| from torch.utils.data import Sampler | |
| __all__ = [ | |
| "DistributedBucketSampler", | |
| ] | |
| T_co = TypeVar("T_co", covariant=True) | |
| class DistributedBucketSampler(Sampler[T_co]): | |
| r""" | |
| sort the dataset wrt. input length | |
| divide samples into buckets | |
| sort within buckets | |
| divide buckets into batches | |
| sort batches | |
| """ | |
| def __init__( | |
| self, | |
| dataset: Dataset, | |
| num_replicas: Optional[int] = None, | |
| rank: Optional[int] = None, | |
| shuffle: bool = True, | |
| seed: int = 0, | |
| drop_last: bool = False, | |
| batch_size: int = 32, | |
| ) -> None: | |
| if num_replicas is None: | |
| if not dist.is_available(): | |
| raise RuntimeError("Requires distributed package to be available") | |
| num_replicas = dist.get_world_size() | |
| if rank is None: | |
| if not dist.is_available(): | |
| raise RuntimeError("Requires distributed package to be available") | |
| rank = dist.get_rank() | |
| torch.cuda.set_device(rank) | |
| if rank >= num_replicas or rank < 0: | |
| raise ValueError( | |
| "Invalid rank {}, rank should be in the interval" | |
| " [0, {}]".format(rank, num_replicas - 1) | |
| ) | |
| self.dataset = dataset | |
| self.num_replicas = num_replicas | |
| self.rank = rank | |
| self.epoch = 0 | |
| self.drop_last = drop_last | |
| # If the dataset length is evenly divisible by # of replicas, then there | |
| # is no need to drop any data, since the dataset will be split equally. | |
| if ( | |
| self.drop_last and len(self.dataset) % self.num_replicas != 0 | |
| ): # type: ignore[arg-type] | |
| # Split to nearest available length that is evenly divisible. | |
| # This is to ensure each rank receives the same amount of data when | |
| # using this Sampler. | |
| self.num_samples = math.ceil( | |
| (len(self.dataset) - self.num_replicas) | |
| / self.num_replicas # type: ignore[arg-type] | |
| ) | |
| else: | |
| self.num_samples = math.ceil( | |
| len(self.dataset) / self.num_replicas | |
| ) # type: ignore[arg-type] | |
| self.total_size = self.num_samples * self.num_replicas | |
| self.shuffle = shuffle | |
| self.seed = seed | |
| self.batch_size = batch_size | |
| self.id_with_length = self._get_sample_lengths() | |
| self.id_buckets = self.make_buckets(bucket_width=2.0) | |
| def _get_sample_lengths(self): | |
| id_with_lengths = [] | |
| for i in range(len(self.dataset)): | |
| id_with_lengths.append((i, self.dataset.get_sample_length(i))) | |
| id_with_lengths.sort(key=lambda x: x[1]) | |
| return id_with_lengths | |
| def make_buckets(self, bucket_width: float = 2.0): | |
| buckets = [] | |
| cur = [] | |
| max_sec = bucket_width | |
| for id, sec in self.id_with_length: | |
| if sec < max_sec: | |
| cur.append(id) | |
| else: | |
| buckets.append(cur) | |
| cur = [id] | |
| max_sec += bucket_width | |
| if len(cur) > 0: | |
| buckets.append(cur) | |
| return buckets | |
| def __iter__(self) -> Iterator[T_co]: | |
| if self.shuffle: | |
| # deterministically shuffle based on epoch and seed | |
| g = torch.Generator() | |
| g.manual_seed(self.seed + self.epoch) | |
| random.seed(self.epoch + self.seed) | |
| shuffled_bucket = [] | |
| for buc in self.id_buckets: | |
| buc_copy = buc.copy() | |
| shuffle(buc_copy) | |
| shuffled_bucket.append(buc_copy) | |
| grouped_batch_size = self.batch_size * self.num_replicas | |
| shuffled_bucket = list(itertools.chain(*shuffled_bucket)) | |
| n_batch = int(math.ceil(len(shuffled_bucket) / grouped_batch_size)) | |
| batches = [ | |
| shuffled_bucket[b * grouped_batch_size : (b + 1) * grouped_batch_size] | |
| for b in range(n_batch) | |
| ] | |
| shuffle(batches) | |
| indices = list(itertools.chain(*batches)) | |
| else: | |
| # type: ignore[arg-type] | |
| indices = list(range(len(self.dataset))) | |
| if not self.drop_last: | |
| # add extra samples to make it evenly divisible | |
| padding_size = self.total_size - len(indices) | |
| if padding_size <= len(indices): | |
| indices += indices[:padding_size] | |
| else: | |
| indices += (indices * math.ceil(padding_size / len(indices)))[ | |
| :padding_size | |
| ] | |
| else: | |
| # remove tail of data to make it evenly divisible. | |
| indices = indices[: self.total_size] | |
| assert len(indices) == self.total_size | |
| # subsample | |
| indices = indices[self.rank : self.total_size : self.num_replicas] | |
| assert len(indices) == self.num_samples | |
| return iter(indices) | |
| def __len__(self) -> int: | |
| return self.num_samples | |
| def set_epoch(self, epoch: int) -> None: | |
| r""" | |
| Sets the epoch for this sampler. When :attr:`shuffle=True`, this ensures all replicas | |
| use a different random ordering for each epoch. Otherwise, the next iteration of this | |
| sampler will yield the same ordering. | |
| Args: | |
| epoch (int): Epoch number. | |
| """ | |
| self.epoch = epoch | |