HBASE-11717 Remove unused config 'hbase.offheapcache.percentage' from hbase-default.xml and book. (Anoop)

hbase-common/src/main/resources/hbase-default.xml

@@ -987,15 +987,6 @@ possible configurations would overwhelm and obscure the important.
     <value>false</value>
     <description>Use Thrift TCompactProtocol binary serialization protocol.</description>
   </property>
-  <property>
-    <name>hbase.offheapcache.percentage</name>
-    <value>0</value>
-    <description>The percentage of the off heap space (-XX:MaxDirectMemorySize) to be
-     allocated towards the experimental off heap "SlabCache" (This is different to
-     the BucketCache -- see the package javadoc for org.apache.hadoop.hbase.io.hfile
-     for more on your options). If you desire the cache to be disabled, simply set this
-      value to 0.</description>
-  </property>
   <property>
     <name>hbase.data.umask.enable</name>
     <value>false</value>

hbase-server/src/test/java/org/apache/hadoop/hbase/mapred/TestTableSnapshotInputFormat.java

@@ -115,9 +115,6 @@ public class TestTableSnapshotInputFormat extends TableSnapshotInputFormatTestBa
         "Snapshot job should be configured for default LruBlockCache.",
         HConstants.HFILE_BLOCK_CACHE_SIZE_DEFAULT,
         job.getFloat(HConstants.HFILE_BLOCK_CACHE_SIZE_KEY, -1), 0.01);
-      Assert.assertEquals(
-        "Snapshot job should not use SlabCache.",
-        0, job.getFloat("hbase.offheapcache.percentage", -1), 0.01);
       Assert.assertEquals(
         "Snapshot job should not use BucketCache.",
         0, job.getFloat("hbase.bucketcache.size", -1), 0.01);

hbase-server/src/test/java/org/apache/hadoop/hbase/mapreduce/TestTableSnapshotInputFormat.java

@@ -162,9 +162,6 @@ public class TestTableSnapshotInputFormat extends TableSnapshotInputFormatTestBa
         "Snapshot job should be configured for default LruBlockCache.",
         HConstants.HFILE_BLOCK_CACHE_SIZE_DEFAULT,
         job.getConfiguration().getFloat(HConstants.HFILE_BLOCK_CACHE_SIZE_KEY, -1), 0.01);
-      Assert.assertEquals(
-        "Snapshot job should not use SlabCache.",
-        0, job.getConfiguration().getFloat("hbase.offheapcache.percentage", -1), 0.01);
       Assert.assertEquals(
         "Snapshot job should not use BucketCache.",
         0, job.getConfiguration().getFloat("hbase.bucketcache.size", -1), 0.01);

src/main/docbkx/upgrading.xml

@@ -398,27 +398,6 @@ Successfully completed Log splitting
                 setup a secure HBase is on the way. </para>
         </section>
 
-        <section
-            xml:id="slabcache">
-            <title>Experimental off-heap cache: SlabCache</title>
-            <para> A new cache was contributed to 0.92.0 to act as a solution between using the
-                “on-heap” cache which is the current LRU cache the region servers have and the
-                operating system cache which is out of our control. To enable
-                    <emphasis>SlabCache</emphasis>, as this feature is being called, set
-                “-XX:MaxDirectMemorySize” in hbase-env.sh to the value for maximum direct memory
-                size and specify <property>hbase.offheapcache.percentage</property> in
-                    <filename>hbase-site.xml</filename> with the percentage that you want to
-                dedicate to off-heap cache. This should only be set for servers and not for clients.
-                Use at your own risk. See this blog post, <link
-                    xlink:href="http://www.cloudera.com/blog/2012/01/caching-in-hbase-slabcache/">Caching
-                    in Apache HBase: SlabCache</link>, for additional information on this new
-                experimental feature. </para>
-            <para>This feature has mostly been eclipsed in later HBases. See <link
-                    xlink:href="https://issues.apache.org/jira/browse/HBASE-7404 ">HBASE-7404 Bucket
-                    Cache:A solution about CMS,Heap Fragment and Big Cache on HBASE</link>,
-                etc.</para>
-        </section>
-
         <section>
             <title>Changes in HBase replication </title>
             <para>0.92.0 adds two new features: multi-slave and multi-master replication. The way to