Enable use of IterableDataset when training with DDP

[syl-taylor-aws]

Feature request

Enable use of IterableDataset when training with NeuronTrainer and DDP. Or is there a design limitation that prevents this?

I can't share the project code, but see below another case for simplicity, which produces the same issue. DistributedSampler expects a dataset with known length, which a IterableDataset doesn't have by design.

Setup

OS: Ubuntu 22.04.4 LTS (kernel 6.5.0-1023-aws)

apt packages

aws-neuronx-collectives/unknown,now 2.21.46.0-69b77134b amd64 [installed]
aws-neuronx-dkms/unknown,now 2.17.17.0 amd64 [installed]
aws-neuronx-runtime-lib/unknown,now 2.21.41.0-fb1705f5f amd64 [installed]
aws-neuronx-tools/unknown,now 2.18.3.0 amd64 [installed]

pip packages

aws-neuronx-runtime-discovery==2.9
neuronx-cc==2.14.227.0+2d4f85be
libneuronxla==2.0.2335
torch==2.1.2
torch-neuronx==2.1.2.2.1.0
torch-xla==2.1.2
transformers==4.41.1
accelerate==0.29.2
optimum-neuron==0.0.24 (also tested 0.0.25.dev0)

Command: torchrun --nproc_per_node=2 issue.py

Code (issue.py)

import torch
from transformers import RobertaForCausalLM
from optimum.neuron import NeuronTrainer as Trainer
from optimum.neuron import NeuronTrainingArguments as TrainingArguments


class CustomIterator:
    def __next__(self):
        return {
            "input_ids": torch.randint(0, 50265, (512,)),
            "labels": torch.randint(0, 50265, (512,))
        }

class CustomDataset(torch.utils.data.IterableDataset):
    def __iter__(self):
        return CustomIterator()


dataset = CustomDataset()

model = RobertaForCausalLM.from_pretrained("roberta-base")

training_args = TrainingArguments(output_dir="./model", max_steps=100)
trainer = Trainer(
    model=model,
    args=training_args,
    train_dataset=dataset
)

trainer.train()

Issue

Traceback (most recent call last):
  File "/home/ubuntu/issue.py", line 29, in <module>
    result = trainer.train()
  File "/home/ubuntu/aws_neuron_venv_pytorch/lib/python3.10/site-packages/optimum/neuron/trainers.py", line 1414, in train
    result = super().train(
  File "/home/ubuntu/aws_neuron_venv_pytorch/lib/python3.10/site-packages/transformers/trainer.py", line 1885, in train
    return inner_training_loop(
  File "/home/ubuntu/aws_neuron_venv_pytorch/lib/python3.10/site-packages/optimum/neuron/utils/require_utils.py", line 51, in wrapper
    return func(*args, **kwargs)
  File "/home/ubuntu/aws_neuron_venv_pytorch/lib/python3.10/site-packages/optimum/neuron/trainers.py", line 686, in _inner_training_loop
    train_dataloader = self.get_train_dataloader()
  File "/home/ubuntu/aws_neuron_venv_pytorch/lib/python3.10/site-packages/transformers/trainer.py", line 897, in get_train_dataloader
    return self.accelerator.prepare(DataLoader(train_dataset, **dataloader_params))
  File "/home/ubuntu/aws_neuron_venv_pytorch/lib/python3.10/site-packages/accelerate/accelerator.py", line 1274, in prepare
    result = tuple(
  File "/home/ubuntu/aws_neuron_venv_pytorch/lib/python3.10/site-packages/accelerate/accelerator.py", line 1275, in <genexpr>
    self._prepare_one(obj, first_pass=True, device_placement=d) for obj, d in zip(args, device_placement)
  File "/home/ubuntu/aws_neuron_venv_pytorch/lib/python3.10/site-packages/accelerate/accelerator.py", line 1149, in _prepare_one
    return self.prepare_data_loader(obj, device_placement=device_placement)
  File "/home/ubuntu/aws_neuron_venv_pytorch/lib/python3.10/site-packages/optimum/neuron/accelerate/accelerator.py", line 223, in prepare_data_loader
    data_loader = self._prepare_data_loader_for_distributed(
  File "/home/ubuntu/aws_neuron_venv_pytorch/lib/python3.10/site-packages/optimum/neuron/accelerate/accelerator.py", line 191, in _prepare_data_loader_for_distributed
    sampler = DistributedSampler(data_loader.dataset, num_replicas=num_replicas, rank=rank, shuffle=shuffle)
  File "/home/ubuntu/aws_neuron_venv_pytorch/lib/python3.10/site-packages/torch/utils/data/distributed.py", line 91, in __init__
    self.num_samples = math.ceil(len(self.dataset) / self.num_replicas)  # type: ignore[arg-type]
TypeError: object of type 'CustomDataset' has no len()

Motivation

Have a project for distributed training on Trainium with DDP that requires use of HuggingFace's IterableDataset (when streaming=True in load.py/load_dataset() from package datasets==2.19.0)

Your contribution

N/A. I noticed on Nvidia A100 GPUs (with transformers Trainer) that it uses accelerate.data_loader.DataLoaderDispatcher and does not use DistributedSampler.

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[unography]

Same issue, DDP breaks on using IterableDataset

DistributedSampler doesn't seem to work for IterableDataset. Perhaps a fix might be to use split_dataset_by_node

https://github.com/huggingface/optimum-neuron/blob/v0.0.25/optimum/neuron/accelerate/accelerator.py#L191

Instead of DistributedSampler, to do -

from datasets.distributed import split_dataset_by_node

dataset_on_curr_node = split_dataset_by_node(data_loader.dataset, rank=rank, world_size=num_replicas)

And passing this to the DataLoader without any sampler

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