asyncio increase throughput (pytorch change) (#84301)
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
