[SPARK-8454] Update ShuffleBlockFetcherIterator.next to close previous stream when returning a new one

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Incomplete
• Component/s: Block Manager, Spark Core
• Labels: bulk-closed
• Assignee: Unassigned
• Reporter: Matt Massie
• Created: 18/Jun/15 20:31
• Updated: 17/May/20 18:21
• Resolved: 21/May/19 04:37

Description

For context, see the PR comments at https://github.com/apache/spark/pull/6423#discussion_r31370774

The current HashShuffleReader closes the input stream when all records have been read by using a NextIterator. However, we want the ShuffleBlockFetcherIterator to be more defensive about closing files and releasing memory to protect against other ShuffleReaders which may not.