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Add doc on htablepool and the htable constructor that takes an executor -- text from LarsH 

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1443633 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Michael Stack 2013-02-07 18:01:08 +00:00
parent ab2fede4bd
commit ceb930eac5
2 changed files with 17 additions and 3 deletions
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4
hbase-server/src/main/java/org/apache/hadoop/hbase/client/package-info.java
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@ -179,6 +179,10 @@ public class MyLittleHBaseClient {
more methods. Additionally, there are methods for managing tables in the
HBaseAdmin class.</p>
<p>See also the section in the HBase Reference Guide where it discusses
<a href="http://hbase.apache.org/book.html#client">HBase Client</a>. It
has section on how to access HBase from inside your multithreaded environtment
how to control resources consumed client-side, etc.</p>
</body>
</html>
*/

16
src/docbkx/book.xml
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@ -1488,8 +1488,9 @@ if (!b) {
<section xml:id="client.connections"><title>Connections</title>
<para>For connection configuration information, see <xref linkend="client_dependencies" />.
</para>
<para><link xlink:href="http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/client/HTable.html">HTable</link>
instances are not thread-safe. When creating HTable instances, it is advisable to use the same <link xlink:href="http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/HBaseConfiguration">HBaseConfiguration</link>
<para><emphasis><link xlink:href="http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/client/HTable.html">HTable</link>
instances are not thread-safe</emphasis>. Only one thread use an instance of HTable at any given
time. When creating HTable instances, it is advisable to use the same <link xlink:href="http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/HBaseConfiguration">HBaseConfiguration</link>
instance. This will ensure sharing of ZooKeeper and socket instances to the RegionServers
which is usually what you want. For example, this is preferred:
<programlisting>HBaseConfiguration conf = HBaseConfiguration.create();
@ -1505,7 +1506,16 @@ HTable table2 = new HTable(conf2, "myTable");</programlisting>
</para>
<section xml:id="client.connection.pooling"><title>Connection Pooling</title>
<para>For applications which require high-end multithreaded access (e.g., web-servers or application servers that may serve many application threads
in a single JVM), see <link xlink:href="http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/client/HTablePool.html">HTablePool</link>.
in a single JVM), one solution is <link xlink:href="http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/client/HTablePool.html">HTablePool</link>.
But as written currently, it is difficult to control client resource consumption when using HTablePool.
</para>
<para>
Another solution is to precreate an <classname>HConnection</classname> using
<programlisting>HConnectionManager.createConnection(Configuration)</programlisting> as
well as an <classname>ExecutorService</classname>; then use the
<programlisting>HTable(byte[], HConnection, ExecutorService)</programlisting>
constructor to create <classname>HTable</classname> instances on demand.
This construction is very lightweight and resources are controlled/shared if you go this route.
</para>
</section>
</section>