[jira] [Updated] (HBASE-20674) clean up short circuit read logic and docs

["Mike Drob (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-20674?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mike Drob updated HBASE-20674:
------------------------------
    Attachment: HBASE-20674.patch

> clean up short circuit read logic and docs
> ------------------------------------------
>
>                 Key: HBASE-20674
>                 URL: https://issues.apache.org/jira/browse/HBASE-20674
>             Project: HBase
>          Issue Type: Bug
>          Components: regionserver
>    Affects Versions: 2.0.0
>            Reporter: Mike Drob
>            Assignee: Mike Drob
>            Priority: Major
>         Attachments: HBASE-20674.patch
>
>
> Mailing list discussion at https://lists.apache.org/thread.html/f6f73df0ceae29f762f9b9088e3ffd0bf8f109d3dd692df100bf4fd6@%3Cdev.hbase.apache.org%3E
> There are several inconsistencies between how our docs claim we do things and how we actually do things.
> There are two docs sections that attempt to address how SCR should work.
> dfs.client.read.shortcircuit.skip.checksum is advised to set to true, but our code in separate places ignores it and then later sets it to true anyway.
> CommonFSUtils and FSUtils duplicate code related to SCR setup.
> There is a workaround in HFileSystem for a bug that's been fixed in all versions of hadoop that we support. (HADOOP-9307)
> We suggest setting dfs.client.read.shortcircuit.buffer.size to a value that is very close to what we'd set it to anyway, without clearly explaining why this is important.
> There are other properties that we claim are important, but we don't offer any suggestions or explanations.



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