[jira] [Created] (HDFS-5182) BlockReaderLocal must allow zero-copy reads only when the DN believes it's valid

["Colin Patrick McCabe (JIRA)" <ji...@apache.org>]

Colin Patrick McCabe created HDFS-5182:
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             Summary: BlockReaderLocal must allow zero-copy  reads only when the DN believes it's valid
                 Key: HDFS-5182
                 URL: https://issues.apache.org/jira/browse/HDFS-5182
             Project: Hadoop HDFS
          Issue Type: Sub-task
          Components: hdfs-client
    Affects Versions: HDFS-4949
            Reporter: Colin Patrick McCabe
            Assignee: Colin Patrick McCabe


BlockReaderLocal must allow zero-copy reads only when the DN believes it's valid.  This implies adding a new field to the response to REQUEST_SHORT_CIRCUIT_FDS.  We also need some kind of heartbeat from the client to the DN, so that the DN can inform the client when the mapped region is no longer locked into memory.

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