distcp should permit users to limit the number of maps

• Key: HADOOP-3350
• Type: Improvement
• Status: Closed
• Resolution: Fixed
• Priority: Major
• Assignee: Chris Douglas
• Reporter: Chris Douglas
• Fix Version/s: 0.18.0

Description

distcp provides no user-configurable setting to affect the number of maps run during a copy. For large clusters, the current calculation- min(#bytes / 256MB, #nodes * 20)- can be overly aggressive.

Comments

[Chris Douglas]

This retains the existing behavior by default, but observes a "distcp.max.map.tasks" parameter.

[Hadoop QA]

-1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12381473/3350-0.patch
against trunk revision 653638.

+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/2405/testReport/
Findbugs warnings: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2405/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2405/artifact/trunk/build/test/checkstyle-errors.html
Console output: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2405/console

This message is automatically generated.

[Owen O'Malley]

You seem to be missing testcase and documentation.

[Chris Douglas]

Patch adds and documents a -m option to set the maximum number of maps, a distcp.bytes.per.map property governing the obvious, and a test case.

[Hadoop QA]

+1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12381797/3350-1.patch
against trunk revision 654941.

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

+1 tests included. The patch appears to include 3 new or modified tests.

+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/2442/testReport/
Findbugs warnings: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2442/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2442/artifact/trunk/build/test/checkstyle-errors.html
Console output: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2442/console

This message is automatically generated.

[Tsz Wo (Nicholas), SZE]

+1 patch looks good

[Chris Douglas]

I just committed this.

[Hudson]

Integrated in Hadoop-trunk #493 (See http://hudson.zones.apache.org/hudson/job/Hadoop-trunk/493/)