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From "Todd Lipcon (Created) (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-2751) Datanode drops OS cache behind reads even for short reads
Date Wed, 04 Jan 2012 23:54:39 GMT
Datanode drops OS cache behind reads even for short reads
---------------------------------------------------------

                 Key: HDFS-2751
                 URL: https://issues.apache.org/jira/browse/HDFS-2751
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: data-node
    Affects Versions: 0.23.0, 0.24.0
            Reporter: Todd Lipcon
            Assignee: Todd Lipcon


HDFS-2465 has some code which attempts to disable the "drop cache behind reads" functionality
when the reads are <256KB (eg HBase random access). But this check was missing in the {{close()}}
function, so it always drops cache behind reads regardless of the size of the read. This hurts
HBase random read performance when this patch is enabled.

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