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From dm...@apache.org
Subject svn commit: r1324730 - in /hbase/trunk/src/docbkx: book.xml configuration.xml
Date Wed, 11 Apr 2012 12:20:22 GMT
Author: dmeil
Date: Wed Apr 11 12:20:22 2012
New Revision: 1324730

URL: http://svn.apache.org/viewvc?rev=1324730&view=rev
Log:
hbase-5764 adding turning off SpecEx in Config chapter recommendations

Modified:
    hbase/trunk/src/docbkx/book.xml
    hbase/trunk/src/docbkx/configuration.xml

Modified: hbase/trunk/src/docbkx/book.xml
URL: http://svn.apache.org/viewvc/hbase/trunk/src/docbkx/book.xml?rev=1324730&r1=1324729&r2=1324730&view=diff
==============================================================================
--- hbase/trunk/src/docbkx/book.xml (original)
+++ hbase/trunk/src/docbkx/book.xml Wed Apr 11 12:20:22 2012
@@ -1253,6 +1253,8 @@ if (!b) {
       map-tasks which will double-write your data to HBase; this is probably
       not what you want.
   </para>
+  <para>See <xref linkend="spec.ex"/> for more information.
+  </para>
   </section>
   </chapter>  <!--  mapreduce -->
 

Modified: hbase/trunk/src/docbkx/configuration.xml
URL: http://svn.apache.org/viewvc/hbase/trunk/src/docbkx/configuration.xml?rev=1324730&r1=1324729&r2=1324730&view=diff
==============================================================================
--- hbase/trunk/src/docbkx/configuration.xml (original)
+++ hbase/trunk/src/docbkx/configuration.xml Wed Apr 11 12:20:22 2012
@@ -1585,6 +1585,13 @@ of all regions.
       <para>For more information about compactions and the compaction file selection
process, see <xref linkend="compaction"/></para>
       </section>
       
+      <section xml:id="spec.ex"><title>Speculative Execution</title>
+        <para>Speculative Execution of MapReduce tasks is on by default, and for HBase
clusters it is generally advised to turn off 
+        Speculative Execution at a system-level unless you need it for a specific case, where
it can be configured per-job.
+        Set the properties <varname>mapred.map.tasks.speculative.execution</varname>
and 
+        <varname>mapred.reduce.tasks.speculative.execution</varname> to false.
+        </para>
+      </section>
       </section>
 
       <section xml:id="other_configuration"><title>Other Configurations</title>
@@ -1602,6 +1609,7 @@ of all regions.
            on the size you need by surveying regionserver UIs; you'll see index block size
accounted near the
            top of the webpage).</para>
          </section>
+         
       </section>
       
       </section> <!--  important config -->



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