Better documentation of controls for memory limits on hadoop daemons and Map-Reduce tasks

• Key: HADOOP-2762
• Type: Improvement
• Status: Closed
• Resolution: Fixed
• Priority: Blocker
• Assignee: Amareshwari Sriramadasu
• Reporter: Arun C Murthy
• Component/s: documentation, scripts
• Affects Version/s: 0.16.0
• Fix Version/s: 0.18.0

Description

We have had a spate of questions about memory usage of hadoop daemons and Map-Reduce jobs and how to configure them.

We should better document mapred.child.java.opts in the Map-Reduce tutorial and cluser_setup.html and link to http://hadoop.apache.org/core/docs/r0.15.3/cluster_setup.html#Configuring+the+Environment+of+the+Hadoop+Daemons.

Comments

[Amareshwari Sriramadasu]

Here is patch improving the documentation for memory controls.

[Hadoop QA]

-1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12383826/patch-2762.txt
against trunk revision 666620.

+1 @author. The patch does not contain any @author tags.

-1 tests included. The patch doesn't appear to include any new or modified tests.
Please justify why no tests are needed for this patch.

+1 javadoc. The javadoc tool did not generate any warning messages.

+1 javac. The applied patch does not increase the total number of javac compiler warnings.

+1 findbugs. The patch does not introduce any new Findbugs warnings.

+1 release audit. The applied patch does not increase the total number of release audit warnings.

+1 core tests. The patch passed core unit tests.

+1 contrib tests. The patch passed contrib unit tests.

Test results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2639/testReport/
Findbugs warnings: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2639/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2639/artifact/trunk/build/test/checkstyle-errors.html
Console output: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2639/console

This message is automatically generated.

[Arun C Murthy]

Amareshwari, do you mind adding some illustrative examples for the HADOOP_*_OPTS? For e.g. how to set up it so that NameNode/JobTracker have higher memory limits than Datanode/TaskTracker.

[Amareshwari Sriramadasu]

Unfortunately HADOOP_*_OPTS can not be used for setting up memory limits, because HADOOP_HEAPSIZE is used to set -Xmx limit for the daemons.
Thus, each daemon should have different HADOOP_HEAPSIZE configured for different memory limits.

[Amareshwari Sriramadasu]

Added a table describing various HADOOP_*_OPTS available to the earlier patch.

[Hadoop QA]

-1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12383945/patch-2762.txt
against trunk revision 667040.

+1 @author. The patch does not contain any @author tags.

-1 tests included. The patch doesn't appear to include any new or modified tests.
Please justify why no tests are needed for this patch.

+1 javadoc. The javadoc tool did not generate any warning messages.

+1 javac. The applied patch does not increase the total number of javac compiler warnings.

+1 findbugs. The patch does not introduce any new Findbugs warnings.

+1 release audit. The applied patch does not increase the total number of release audit warnings.

+1 core tests. The patch passed core unit tests.

+1 contrib tests. The patch passed contrib unit tests.

Test results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2652/testReport/
Findbugs warnings: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2652/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2652/artifact/trunk/build/test/checkstyle-errors.html
Console output: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2652/console

This message is automatically generated.

[Devaraj Das]

Minor one - pls specify the unit for mapred.child.ulimit value.

[Amareshwari Sriramadasu]

Patch adding the units for mapred.child.ulimit

[Hadoop QA]

-1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12384102/patch-2762.txt
against trunk revision 668396.

+1 @author. The patch does not contain any @author tags.

-1 tests included. The patch doesn't appear to include any new or modified tests.
Please justify why no tests are needed for this patch.

+1 javadoc. The javadoc tool did not generate any warning messages.

+1 javac. The applied patch does not increase the total number of javac compiler warnings.

+1 findbugs. The patch does not introduce any new Findbugs warnings.

+1 release audit. The applied patch does not increase the total number of release audit warnings.

+1 core tests. The patch passed core unit tests.

+1 contrib tests. The patch passed contrib unit tests.

Test results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2667/testReport/
Findbugs warnings: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2667/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2667/artifact/trunk/build/test/checkstyle-errors.html
Console output: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2667/console

This message is automatically generated.

[Devaraj Das]

I just committed this. Thanks, Amareshwari!

[Hudson]

Integrated in Hadoop-trunk #521 (See http://hudson.zones.apache.org/hudson/job/Hadoop-trunk/521/)