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HBASE-6856 Document the LeaseException thrown in scanner next 

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1388604 13f79535-47bb-0310-9956-ffa450edef68
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Michael Stack 2012-09-21 18:31:22 +00:00
parent 2cd3c54de4
commit 93d2fc5ce2
1 changed files with 12 additions and 0 deletions
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src/docbkx/troubleshooting.xml
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@ -530,6 +530,18 @@ hadoop 17789 155 35.2 9067824 8604364 ? S<l Mar04 9855:48 /usr/java/j
<para>See <xref linkend="perf.hbase.client.caching"/>.
</para>
</section>
<section xml:id="trouble.client.lease.exception">
<title><classname>LeaseException</classname> when calling <classname>Scanner.next</classname></title>
<para>
In some situations clients that fetch data from a RegionServer get a LeaseException instead of the usual
<xref linkend="trouble.client.scantimeout" />. Usually the source of the exception is
<classname>org.apache.hadoop.hbase.regionserver.Leases.removeLease(Leases.java:230)</classname> (line number may vary).
It tends to happen in the context of a slow/freezing RegionServer#next call.
It can be prevented by having <varname>hbase.rpc.timeout</varname> > <varname>hbase.regionserver.lease.period</varname>.
Harsh J investigated the issue as part of the mailing list thread
<link xlink:href="http://mail-archives.apache.org/mod_mbox/hbase-user/201209.mbox/%3CCAOcnVr3R-LqtKhFsk8Bhrm-YW2i9O6J6Fhjz2h7q6_sxvwd2yw%40mail.gmail.com%3E">HBase, mail # user - Lease does not exist exceptions</link>
</para>
</section>
<section xml:id="trouble.client.scarylogs">
<title>Shell or client application throws lots of scary exceptions during normal operation</title>
<para>Since 0.20.0 the default log level for <code>org.apache.hadoop.hbase.*</code>is DEBUG. </para>