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HBASE-3888 book.xml - filled in architecture 'daemon' section 

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1124467 13f79535-47bb-0310-9956-ffa450edef68
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Michael Stack 2011-05-18 23:49:53 +00:00
parent 9e4d90cdf1
commit cf8be18f15
1 changed files with 62 additions and 0 deletions
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src/docbkx/book.xml
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@ -748,8 +748,70 @@ HTable table2 = new HTable(conf2, "myTable");</programlisting>
<section xml:id="daemons">
<title>Daemons</title>
<section xml:id="master"><title>Master</title>
<para><code>HMaster</code> is the implementation of the Master Server. The Master server
is responsible for monitoring all RegionServer instances in the cluster, and is
the interface for all metadata changes.
</para>
<section xml:id="master.startup"><title>Startup Behavior</title>
<para>If run in a multi-Master environment, all Masters compete to run the cluster. If the active
Master loses it's lease in ZooKeeper (or the Master shuts down), then then the remaining Masters jostle to
take over the Master role.
</para>
</section>
<section xml:id="master.api"><title>Interface</title>
<para>The methods exposed by <code>HMasterInterface</code> are primarily metadata-oriented methods:
<itemizedlist>
<listitem>Table (createTable, modifyTable, removeTable, enable, disable)
</listitem>
<listitem>ColumnFamily (addColumn, modifyColumn, removeColumn)
</listitem>
<listitem>Region (move, assign, unassign)
</listitem>
</itemizedlist>
For example, when the <code>HBaseAdmin</code> method <code>disableTable</code> is invoked, it is serviced by the Master server.
</para>
</section>
<section xml:id="master.processes"><title>Processes</title>
<para>The Master runs several background threads:
<itemizedlist>
<listitem><code>LoadBalancer</code> periodically reassign regions in the cluster.
</listitem>
<listitem><code>CatalogJanitor</code> periodically checks and cleans up the .META. table.
</listitem>
</itemizedlist>
</para>
</section>
</section>
<section xml:id="regionserver.arch"><title>RegionServer</title>
<para><code>HRegionServer</code> is the RegionServer implementation. It is responsible for serving and managing regions.
</para>
<section xml:id="regionserver.arch.api"><title>Interface</title>
<para>The methods exposed by <code>HRegionRegionInterface</code> contain both data-oriented and region-maintenance methods:
<itemizedlist>
<listitem>Data (get, put, delete, next, etc.)
</listitem>
<listitem>Region (splitRegion, compactRegion, etc.)
</listitem>
</itemizedlist>
For example, when the <code>HBaseAdmin</code> method <code>majorCompact</code> is invoked on a table, the client is actually iterating through
all regions for the specified table and requesting a major compaction directly to each region.
</para>
</section>
<section xml:id="regionserver.arch.processes"><title>Processes</title>
<para>The RegionServer runs a variety of background threads:</para>
<itemizedlist>
<listitem><code>CompactSplitThread</code> checks for splits and handle minor compactions.
</listitem>
<listitem><code>MajorCompactionChecker</code> checks for major compactions.
</listitem>
<listitem><code>MemStoreFlusher</code> periodically flushes in-memory writes in the MemStore to StoreFiles.
</listitem>
<listitem><code>LogRoller</code> periodically checks the RegionServer's HLog.
</listitem>
</itemizedlist>
</section>
</section>
</section>