[
https://issues.apache.org/jira/browse/HDFS-6450?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14350869#comment-14350869
]
Colin Patrick McCabe commented on HDFS-6450:
--------------------------------------------
I think it would be possible to support hedged non-positional reads in
{{BlockReaderLocal}}, but difficult. First we would have to stop re-using the
same FD for all instances of a BlockReaderLocal that were reading the same
replica. Perhaps we could use dup to create a new FD per blockreader without
doing multiple opens. Then we could close the blockreader FD if the local read
were being slow.
I think it's much easier to just implement hedged non-positional reads in the
erasure coding-specific subclass of DFSInputStream.
I also think we may want to create a base class for DFSInputStream that both
the raid and the non-raid code path inherit from. Inheriting from the non-raid
code path is weird because there is a lot of stuff that is not relevant.
> Support non-positional hedged reads in HDFS
> -------------------------------------------
>
> Key: HDFS-6450
> URL: https://issues.apache.org/jira/browse/HDFS-6450
> Project: Hadoop HDFS
> Issue Type: Improvement
> Affects Versions: 2.4.0
> Reporter: Colin Patrick McCabe
> Assignee: Liang Xie
> Attachments: HDFS-6450-like-pread.txt
>
>
> HDFS-5776 added support for hedged positional reads. We should also support
> hedged non-position reads (aka regular reads).
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
