    def get_batch_iterator(
        self,
        dataset,
        max_tokens=None,
        max_sentences=None,
        max_positions=None,
        ignore_invalid_inputs=False,
        required_batch_size_multiple=1,
        seed=1,
        num_shards=1,
        shard_id=0,
        num_workers=0,
        epoch=1,
        data_buffer_size=0,
        disable_iterator_cache=False,
        skip_remainder_batch=False,
        grouped_shuffling=False,
        update_epoch_batch_itr=False,
    ):
        """
        Get an iterator that yields batches of data from the given dataset.

        Args:
            dataset (~fairseq.data.FairseqDataset): dataset to batch
            max_tokens (int, optional): max number of tokens in each batch
                (default: None).
            max_sentences (int, optional): max number of sentences in each
                batch (default: None).
            max_positions (optional): max sentence length supported by the
                model (default: None).
            ignore_invalid_inputs (bool, optional): don't raise Exception for
                sentences that are too long (default: False).
            required_batch_size_multiple (int, optional): require batch size to
                be a multiple of N (default: 1).
            seed (int, optional): seed for random number generator for
                reproducibility (default: 1).
            num_shards (int, optional): shard the data iterator into N
                shards (default: 1).
            shard_id (int, optional): which shard of the data iterator to
                return (default: 0).
            num_workers (int, optional): how many subprocesses to use for data
                loading. 0 means the data will be loaded in the main process
                (default: 0).
            epoch (int, optional): the epoch to start the iterator from
                (default: 0).
            data_buffer_size (int, optional): number of batches to
                preload (default: 0).
            disable_iterator_cache (bool, optional): don't cache the
                EpochBatchIterator (ignores `FairseqTask::can_reuse_epoch_itr`)
                (default: False).
            grouped_shuffling (bool, optional): group batches with each groups
                containing num_shards batches and shuffle groups. Reduces difference
                between sequence lengths among workers for batches sorted by length.
            update_epoch_batch_itr (bool optional): if true then donot use the cached
                batch iterator for the epoch

        Returns:
            ~fairseq.iterators.EpochBatchIterator: a batched iterator over the
                given dataset split
        """
        # initialize the dataset with the correct starting epoch
        assert isinstance(dataset, FairseqDataset)
        if dataset in self.dataset_to_epoch_iter:
            return self.dataset_to_epoch_iter[dataset]
        if self.args.sampling_method == "RoundRobin":
            batch_iter = super().get_batch_iterator(
                dataset,
                max_tokens=max_tokens,
                max_sentences=max_sentences,
                max_positions=max_positions,
                ignore_invalid_inputs=ignore_invalid_inputs,
                required_batch_size_multiple=required_batch_size_multiple,
                seed=seed,
                num_shards=num_shards,
                shard_id=shard_id,
                num_workers=num_workers,
                epoch=epoch,
                data_buffer_size=data_buffer_size,
                disable_iterator_cache=disable_iterator_cache,
                skip_remainder_batch=skip_remainder_batch,
                update_epoch_batch_itr=update_epoch_batch_itr,
            )
            self.dataset_to_epoch_iter[dataset] = batch_iter
            return batch_iter

        construct_batch_sampler = self.create_batch_sampler_func(
            max_positions,
            ignore_invalid_inputs,
            max_tokens,
            max_sentences,
            required_batch_size_multiple=required_batch_size_multiple,
            seed=seed,
        )

        epoch_iter = iterators.EpochBatchIterator(
            dataset=dataset,
            collate_fn=dataset.collater,
            batch_sampler=construct_batch_sampler,
            seed=seed,
            num_shards=num_shards,
            shard_id=shard_id,
            num_workers=num_workers,
            epoch=epoch,
        )
        return epoch_iter
Get an iterator that yields batches of data from the given dataset.

Args:
dataset (~fairseq.data.FairseqDataset): dataset to batch
max_tokens (int, optional): max number of tokens in each batch
(default: None).
max_sentences (int, optional): max number of sentences in each
batch (default: None).
max_positions (optional): max sentence length supported by the
model (default: None).
ignore_invalid_inputs (bool, optional): don't raise Exception for
sentences that are too long (default: False).
required_batch_size_multiple (int, optional): require batch size to
be a multiple of N (default: 1).
seed (int, optional): seed for random number generator for
reproducibility (default: 1).
num_shards (int, optional): shard the data iterator into N
shards (default: 1).
shard_id (int, optional): which shard of the data iterator to
return (default: 0).
num_workers (int, optional): how many subprocesses to use for data
loading. 0 means the data will be loaded in the main process
(default: 0).
epoch (int, optional): the epoch to start the iterator from
(default: 0).
data_buffer_size (int, optional): number of batches to
preload (default: 0).
disable_iterator_cache (bool, optional): don't cache the
EpochBatchIterator (ignores `FairseqTask::can_reuse_epoch_itr`)
(default: False).
grouped_shuffling (bool, optional): group batches with each groups
containing num_shards batches and shuffle groups. Reduces difference
between sequence lengths among workers for batches sorted by length.
update_epoch_batch_itr (bool optional): if true then donot use the cached
batch iterator for the epoch

Returns:
~fairseq.iterators.EpochBatchIterator: a batched iterator over the
given dataset split
fairseq/tasks/translation_multi_simple_epoch.py