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https://issues.apache.org/jira/browse/HADOOP-4304?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12647488#action_12647488
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Klaas Bosteels commented on HADOOP-4304:
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It actually is necessary that the Dumbo python module gets installed in the
system directory of the machine from which you run your jobs, because when you
run e.g.
python wordcount.py -hadoop ~hadoop/hadoop-0.17.2.1 -input brian.txt -output
brian-wc -file excludes.txt
the "dumbo.run()" call gets executed on that machine, which makes Dumbo
generate and excute the Streaming command
/home/hadoop/hadoop-0.17.2.1/bin/hadoop jar
/home/hadoop/hadoop-0.17.2.1/contrib/streaming/hadoop-0.17.2.1-streaming.jar
-input 'brian.txt' -output 'brian-wc' -file 'excludes.txt' -mapper 'python
wordcount.py map 0' -reducer 'python wordcount.py red 0' -file 'wordcount.py'
-file '/usr/lib/python2.4/site-packages/dumbo.py' -jobconf
'mapred.job.name=wordcount.py'
under the hood. The part
-file '/usr/lib/python2.4/site-packages/dumbo.py'
of this automatically generated command makes sure that the Dumbo module from
the system dir is put in the working dir on each cluster node (i.e. it is not
necessary to install the Dumbo python module in the system dir on the cluster
nodes), and the extra args supplied to "python wordcount.py" in
-mapper 'python wordcount.py map 0'
-reducer 'python wordcount.py red 0'
allow Dumbo to know that it has to run the actual map or reduce instead of
generating and executing a Streaming command on the nodes. Hence, we need the
ability to install Dumbo in the system dir in order to make it very easy to
start jobs, which is one of the main features of dumbo (some more info about
this can be found at http://github.com/klbostee/dumbo/wikis/running-programs).
I also do not think that the "classes" and "test" dirs are superfluous (but I
might very well be wrong). As mentioned in the description of this ticket,
Dumbo also consists of some helper Java code like e.g. a special inputformat
that allows to easily use sequencefiles as input for Dumbo programs (there
currently is no public documentation for these features available, but we are
planning to change that once this patch gets approved), and there are also some
unit tests for this helper code.
Concerning the NFS mounting I'm not really sure what you mean. Maybe that
"excludes.txt" has to be in the cwd? This is handled by adding the option
"-file excludes.txt" to the command (like in the command above), so there is no
need for any NFS mounts...
> Add Dumbo to contrib
> --------------------
>
> Key: HADOOP-4304
> URL: https://issues.apache.org/jira/browse/HADOOP-4304
> Project: Hadoop Core
> Issue Type: New Feature
> Reporter: Klaas Bosteels
> Assignee: Klaas Bosteels
> Priority: Minor
> Attachments: hadoop-4304-v2.patch, hadoop-4304-v3.patch,
> hadoop-4304.patch
>
>
> Originally, Dumbo was a simple Python module developed at Last.fm to make
> writing and running Hadoop Streaming programs very easy, but now it also
> consists of some (up till now unreleased) helper code in Java (although it
> can still be used without the Java code). We propose to add Dumbo to
> "src/contrib" such that the Java classes get build/installed together with
> the rest of Hadoop, and the Python module can be installed separately at
> will. A tar.gz of the directory that would have to be added to "src/contrib"
> is available at
> http://static.last.fm/dumbo/dumbo-contrib.tar.gz
> and more info about Dumbo can be found here:
> * Basic documentation: http://github.com/klbostee/dumbo/wikis
> * Presentation at HUG (where it was first suggested to add Dumbo to contrib):
> http://skillsmatter.com/podcast/home/dumbo-hadoop-streaming-made-elegant-and-easy
> * Initial announcement:
> http://blog.last.fm/2008/05/29/python-hadoop-flying-circus-elephant
> For some of the more advanced features of Dumbo (in particular the ones for
> which the Java classes are needed) there is no public documentation yet, but
> we could easily fill that gap by moving some of the internal Last.fm
> documentation to the Hadoop wiki.
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