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Fix up the doc of 'dfs.client.read.shortcircuit.buffer.size' 

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1591492 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Michael Stack 2014-04-30 22:04:25 +00:00
parent c1d32df547
commit 9047981a0c
1 changed files with 3 additions and 2 deletions
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src/main/docbkx/performance.xml
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@ -726,8 +726,9 @@ configurations.
</para> </para>
<note xml:id="dfs.client.read.shortcircuit.buffer.size"> <note xml:id="dfs.client.read.shortcircuit.buffer.size">
<title>dfs.client.read.shortcircuit.buffer.size</title> <title>dfs.client.read.shortcircuit.buffer.size</title>
<para>The default for this value is too high when running on a highly trafficed HBase. Set it down from its <para>The default for this value is too high when running on a highly trafficed HBase.
1M default down to 128k or so. Put this configuration in the HBase configs (its a HDFS client-side configuration). In HBase, if this value has not been set, we set it down from the default of 1M to 128k
(Since HBase 0.98.0 and 0.96.1). See <link xlink:href="https://issues.apache.org/jira/browse/HBASE-8143">HBASE-8143 HBase on Hadoop 2 with local short circuit reads (ssr) causes OOM</link>).
The Hadoop DFSClient in HBase will allocate a direct byte buffer of this size for <emphasis>each</emphasis> The Hadoop DFSClient in HBase will allocate a direct byte buffer of this size for <emphasis>each</emphasis>
block it has open; given HBase keeps its HDFS files open all the time, this can add up quickly.</para> block it has open; given HBase keeps its HDFS files open all the time, this can add up quickly.</para>
</note> </note>