Author: szetszwo
Date: Sat Mar 21 01:15:48 2009
New Revision: 756858
URL: http://svn.apache.org/viewvc?rev=756858&view=rev
Log:
HADOOP-5519. Remove claims from mapred-default.xml that prime numbers of tasks
are helpful. (Owen O'Malley via szetszwo)
Modified:
hadoop/core/trunk/CHANGES.txt
hadoop/core/trunk/src/mapred/mapred-default.xml
Modified: hadoop/core/trunk/CHANGES.txt
URL:
http://svn.apache.org/viewvc/hadoop/core/trunk/CHANGES.txt?rev=756858&r1=756857&r2=756858&view=diff
==============================================================================
--- hadoop/core/trunk/CHANGES.txt (original)
+++ hadoop/core/trunk/CHANGES.txt Sat Mar 21 01:15:48 2009
@@ -1077,6 +1077,9 @@
HADOOP-5520. Fix a typo in disk quota help message. (Ravi Phulari
via szetszwo)
+ HADOOP-5519. Remove claims from mapred-default.xml that prime numbers
+ of tasks are helpful. (Owen O'Malley via szetszwo)
+
Release 0.19.2 - Unreleased
BUG FIXES
Modified: hadoop/core/trunk/src/mapred/mapred-default.xml
URL:
http://svn.apache.org/viewvc/hadoop/core/trunk/src/mapred/mapred-default.xml?rev=756858&r1=756857&r2=756858&view=diff
==============================================================================
--- hadoop/core/trunk/src/mapred/mapred-default.xml (original)
+++ hadoop/core/trunk/src/mapred/mapred-default.xml Sat Mar 21 01:15:48 2009
@@ -322,8 +322,7 @@
<property>
<name>mapred.map.tasks</name>
<value>2</value>
- <description>The default number of map tasks per job. Typically set
- to a prime several times greater than number of available hosts.
+ <description>The default number of map tasks per job.
Ignored when mapred.job.tracker is "local".
</description>
</property>
@@ -331,9 +330,10 @@
<property>
<name>mapred.reduce.tasks</name>
<value>1</value>
- <description>The default number of reduce tasks per job. Typically set
- to a prime close to the number of available hosts. Ignored when
- mapred.job.tracker is "local".
+ <description>The default number of reduce tasks per job. Typically set to 99%
+ of the cluster's reduce capacity, so that if a node fails the reduces can
+ still be executed in a single wave.
+ Ignored when mapred.job.tracker is "local".
</description>
</property>
