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# coding=utf-8
# Copyright (c) 2020, NVIDIA CORPORATION. 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.
"""Dataloaders."""
import random
import torch
import numpy as np
from torch.utils.data import Dataset
from megatron import get_args
from megatron import mpu
def build_pretraining_data_loader(dataset, consumed_samples):
"""Buld dataloader given an input dataset."""
if dataset is None:
return None
args = get_args()
# Megatron sampler
if args.dataloader_type == 'single':
batch_sampler = MegatronPretrainingSampler(
total_samples=len(dataset),
consumed_samples=consumed_samples,
micro_batch_size=args.micro_batch_size,
data_parallel_rank=mpu.get_data_parallel_rank(),
data_parallel_size=mpu.get_data_parallel_world_size())
elif args.dataloader_type == 'cyclic':
batch_sampler = MegatronPretrainingRandomSampler(
dataset,
total_samples=len(dataset),
consumed_samples=consumed_samples,
micro_batch_size=args.micro_batch_size,
data_parallel_rank=mpu.get_data_parallel_rank(),
data_parallel_size=mpu.get_data_parallel_world_size(),
data_sharding=args.data_sharding)
else:
raise Exception('{} dataloader type is not supported.'.format(
args.dataloader_type))
# Torch dataloader.
return torch.utils.data.DataLoader(dataset,
batch_sampler=batch_sampler,
num_workers=args.num_workers,
pin_memory=True)
class MegatronPretrainingSampler:
def __init__(self, total_samples, consumed_samples, micro_batch_size,
data_parallel_rank, data_parallel_size, drop_last=True):
# Keep a copy of input params for later use.
self.total_samples = total_samples
self.consumed_samples = consumed_samples
self.micro_batch_size = micro_batch_size
self.data_parallel_rank = data_parallel_rank
self.micro_batch_times_data_parallel_size = \
self.micro_batch_size * data_parallel_size
self.drop_last = drop_last
# Sanity checks.
assert self.total_samples > 0, \
'no sample to consume: {}'.format(self.total_samples)
assert self.consumed_samples < self.total_samples, \
'no samples left to consume: {}, {}'.format(self.consumed_samples,
self.total_samples)
assert self.micro_batch_size > 0
assert data_parallel_size > 0
assert self.data_parallel_rank < data_parallel_size, \
'data_parallel_rank should be smaller than data size: {}, ' \
'{}'.format(self.data_parallel_rank, data_parallel_size)
def __len__(self):
return self.total_samples
def get_start_end_idx(self):
start_idx = self.data_parallel_rank * self.micro_batch_size
end_idx = start_idx + self.micro_batch_size
return start_idx, end_idx
def __iter__(self):
batch = []
# Last batch will be dropped if drop_last is not set False
for idx in range(self.consumed_samples, self.total_samples):
batch.append(idx)
if len(batch) == self.micro_batch_times_data_parallel_size:
start_idx, end_idx = self.get_start_end_idx()
yield batch[start_idx:end_idx]
batch = []
# Check the last partial batch and see drop_last is set
if len(batch) > 0 and not self.drop_last:
start_idx, end_idx = self.get_start_end_idx()
yield batch[start_idx:end_idx]
class RandomSeedDataset(Dataset):
def __init__(self, dataset):
args = get_args()
self.base_seed = args.seed
self.curr_seed = args.seed
self.dataset = dataset
def __len__(self):
return len(self.dataset)
def set_epoch(self, epoch):
self.curr_seed = self.base_seed + epoch
def __getitem__(self, idx):
seed = idx + self.curr_seed
torch.manual_seed(seed)
random.seed(seed)
np.random.seed(seed)
return self.dataset[idx]
class MegatronPretrainingRandomSampler:
def __init__(self, dataset, total_samples, consumed_samples, micro_batch_size,
data_parallel_rank, data_parallel_size, data_sharding):
# Keep a copy of input params for later use.
self.dataset = dataset
self.total_samples = total_samples
self.consumed_samples = consumed_samples
self.micro_batch_size = micro_batch_size
self.data_parallel_rank = data_parallel_rank
self.data_parallel_size = data_parallel_size
self.data_sharding = data_sharding
self.micro_batch_times_data_parallel_size = \
self.micro_batch_size * data_parallel_size
self.last_batch_size = \
self.total_samples % self.micro_batch_times_data_parallel_size
# Sanity checks.
assert self.total_samples > 0, \
'no sample to consume: {}'.format(self.total_samples)
assert self.micro_batch_size > 0
assert data_parallel_size > 0
assert self.data_parallel_rank < data_parallel_size, \
'data_parallel_rank should be smaller than data size: {}, ' \
'{}'.format(self.data_parallel_rank, data_parallel_size)
def __len__(self):
return self.total_samples
def __iter__(self):
active_total_samples = self.total_samples - self.last_batch_size
self.epoch = self.consumed_samples // active_total_samples
current_epoch_samples = self.consumed_samples % active_total_samples
assert current_epoch_samples % self.micro_batch_times_data_parallel_size == 0
if isinstance(self.dataset, RandomSeedDataset):
self.dataset.set_epoch(self.epoch)
# data sharding and random sampling
if self.data_sharding:
bucket_size = (self.total_samples // self.micro_batch_times_data_parallel_size) \
* self.micro_batch_size
bucket_offset = current_epoch_samples // self.data_parallel_size
start_idx = self.data_parallel_rank * bucket_size
g = torch.Generator()
g.manual_seed(self.epoch)
random_idx = torch.randperm(bucket_size, generator=g).tolist()
idx_range = [start_idx + x for x in random_idx[bucket_offset:]]
else:
full_bucket_size = (self.total_samples // self.micro_batch_size) \
* self.micro_batch_size
full_bucket_offset = current_epoch_samples
g = torch.Generator()
g.manual_seed(self.epoch)
idx_range_total = \
torch.randperm(full_bucket_size, generator=g).tolist()
idx_range_active = idx_range_total[full_bucket_offset:]
idx_range = idx_range_active[self.data_parallel_rank::self.data_parallel_size]
batch = []
# Last batch if not complete will be dropped.
for idx in idx_range:
batch.append(idx)
if len(batch) == self.micro_batch_size:
self.consumed_samples += self.micro_batch_times_data_parallel_size
yield batch
batch = []
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