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Accumulo >> mail # user >> Accumulo Map Reduce is not distributed

Cornish, Duane C. 2012-11-02, 20:53
John Vines 2012-11-02, 21:04
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RE: Accumulo Map Reduce is not distributed
Thanks for the prompt response John!
When I say that I'm pre-splitting my table, I mean I am using the tableOperations().addSplits(table,splits) command.  I have verified that this is correctly splitting my table into 4 tablets and it is being distributed across my cloud before I start my map reduce job.

Now, I only kick off the job once, but it appears that 4 separate jobs run (one after the other).  The first one reaches 100% in its map phase (and based on my output only handled ¼ of the data), then the next job starts at 0% and reaches 100%, and so on.  So I think I'm "only running one mapper at a time in an MR job that has 4 mappers total.".  I have 2 mapper slots per node.  My hadoop is set up so that one machine is the namenode and the other 3 are datanodes.  This gives me 6 slots total.  (This is not congruent to my accumulo where the master is also a slave - giving 4 total slaves).

My map reduce job is not a chain job, so all 4 tablets should be able to run at the same time.

Here is my job class code below:

import org.apache.accumulo.core.security.Authorizations;
import org.apache.accumulo.core.client.mapreduce.AccumuloOutputFormat;
import org.apache.accumulo.core.client.mapreduce.AccumuloRowInputFormat;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.util.Tool;
import org.apache.log4j.Level;
public class Accumulo_FE_MR_Job extends Configured implements Tool{

       private void runOneTable() throws Exception {
        System.out.println("Running Map Reduce Feature Extraction Job");

        Job job  = new Job(getConf(), getClass().getName());



                new Authorizations());

        AccumuloRowInputFormat.setLogLevel(job.getConfiguration(), Level.FATAL);




        AccumuloOutputFormat.setLogLevel(job.getConfiguration(), Level.FATAL);

        if (job.isSuccessful()) {
            System.err.println("Job Successful");
        } else {
            System.err.println("Job Unsuccessful");

       public int run(String[] arg0) throws Exception {
              return 0;


From: John Vines [mailto:[EMAIL PROTECTED]]
Sent: Friday, November 02, 2012 5:04 PM
Subject: Re: Accumulo Map Reduce is not distributed

This sounds like an issue with how your MR environment is configured and/or how you're kicking off your mapreduce.

Accumulo's input formats with automatically set the number of mappers to the number of tablets you have, so you should have seen your job go from 1 mapper to 4. What you describe is you now do 4 MR jobs instead of just one, is that correct? Because that doesn't make a lot of sense, unless by presplitting your table you meant you now have 4 different support tables. Or do you mean that you're only running one mapper at a time in an MR job that has 4 mappers total?

I believe it's somewhere in your kickoff that things may be a bit misconstrued. Just so I'm clear, how many mapper slots do you have per node, is your job a chain MR job, and do you mind sharing your code which sets up and kicks off your MR job so I have an idea of what could be kicking off 4 jobs.


On Fri, Nov 2, 2012 at 4:53 PM, Cornish, Duane C. <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:

I apologize if this discuss should be directed to a hadoop map reduce forum, however, I have some concern that my problem may be with my use of accumulo.

I have a map reduce job that I want to run over data in a table.  I have an index table and a support table which contains a subset of the data in the index table.  I would like to map reduce over the support table on my small 4 node cluster.

I have written a map reduce job that uses the AccumuloRowInputFormat class and sets the support table as its input table.

In my mapper, I read in a row of the support table, and make a call to a static function which pulls information out of the index table.  Next, I use the data pulled back from the function call as input to a call to an external .so file that is stored on the name node.  I then make another static function call to ingest the new data back into the index table.  (I know I could emit this in the reduce step, but what I'm ingesting is formatted in a somewhat complex java object and I already had a static function that ingested it the way I needed it.)  My reduce step is completely empty.

I output print statements from my mapper to see my progress.  The problem that I'm getting is that my entire job ap
William Slacum 2012-11-03, 00:48
David Medinets 2012-11-03, 03:49
Cornish, Duane C. 2012-11-05, 13:56
John Vines 2012-11-05, 14:13
Billie Rinaldi 2012-11-05, 14:40
Cornish, Duane C. 2012-11-05, 14:46
Billie Rinaldi 2012-11-05, 15:03
Cornish, Duane C. 2012-11-05, 16:54
Krishmin Rai 2012-11-05, 17:14
Billie Rinaldi 2012-11-05, 17:18
Cornish, Duane C. 2012-11-06, 13:45
David Medinets 2012-11-06, 14:34
Cornish, Duane C. 2012-11-06, 14:53
Billie Rinaldi 2012-11-06, 15:19
David Medinets 2012-11-05, 15:16