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335033f718
Summary: This diffs add a check in the fetcher, that if the dataset to be fetched has a function "getitems" then use it for fetching a batch of elements, as oppose to one by one. This is benefical for io bounded usage. Differential Revision: D39145980 Pull Request resolved: https://github.com/pytorch/pytorch/pull/84301 Approved by: https://github.com/VitalyFedyunin
62 lines
2.1 KiB
Python
62 lines
2.1 KiB
Python
r""""Contains definitions of the methods used by the _BaseDataLoaderIter to fetch
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data from an iterable-style or map-style dataset. This logic is shared in both
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single- and multi-processing data loading.
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"""
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class _BaseDatasetFetcher(object):
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def __init__(self, dataset, auto_collation, collate_fn, drop_last):
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self.dataset = dataset
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self.auto_collation = auto_collation
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self.collate_fn = collate_fn
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self.drop_last = drop_last
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def fetch(self, possibly_batched_index):
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raise NotImplementedError()
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class _IterableDatasetFetcher(_BaseDatasetFetcher):
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def __init__(self, dataset, auto_collation, collate_fn, drop_last):
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super(_IterableDatasetFetcher, self).__init__(
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dataset, auto_collation, collate_fn, drop_last
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)
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self.dataset_iter = iter(dataset)
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self.ended = False
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def fetch(self, possibly_batched_index):
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if self.ended:
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raise StopIteration
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if self.auto_collation:
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data = []
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for _ in possibly_batched_index:
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try:
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data.append(next(self.dataset_iter))
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except StopIteration:
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self.ended = True
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break
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if len(data) == 0 or (
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self.drop_last and len(data) < len(possibly_batched_index)
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):
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raise StopIteration
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else:
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data = next(self.dataset_iter)
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return self.collate_fn(data)
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class _MapDatasetFetcher(_BaseDatasetFetcher):
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def __init__(self, dataset, auto_collation, collate_fn, drop_last):
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super(_MapDatasetFetcher, self).__init__(
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dataset, auto_collation, collate_fn, drop_last
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)
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def fetch(self, possibly_batched_index):
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if self.auto_collation:
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if hasattr(self.dataset, "__getitems__"):
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data = self.dataset.__getitems__(possibly_batched_index)
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else:
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data = [self.dataset[idx] for idx in possibly_batched_index]
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else:
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data = self.dataset[possibly_batched_index]
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return self.collate_fn(data)
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