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From "Deepesh Khandelwal (JIRA)" <j...@apache.org>
Subject [jira] [Created] (MAPREDUCE-5055) Binary compatibility for the method Reporter.incrCounter(String group, String counter, long amount) between hadoop-1.x and hadoop-2.x
Date Fri, 08 Mar 2013 18:50:12 GMT
Deepesh Khandelwal created MAPREDUCE-5055:
---------------------------------------------

             Summary: Binary compatibility for the method Reporter.incrCounter(String group,
String counter, long amount) between hadoop-1.x and hadoop-2.x
                 Key: MAPREDUCE-5055
                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5055
             Project: Hadoop Map/Reduce
          Issue Type: Bug
          Components: mrv2
    Affects Versions: 2.0.3-alpha
         Environment: Linux
            Reporter: Deepesh Khandelwal


Try to generate a lot of counters that exceed the default max limit so the job errors.
To simulate this edit org.apache.hadoop.examples.RandomWriter class and add the following
in the mapper:
{code}
        for (int i = 0; i < 150; i++) {
          reporter.incrCounter("StringCounter", "counter" + i, 1L);
        }
{code}
Attached is the modified code of RandomWriter.java from branch-1.

When I run it against branch-1,
{code}
hadoop jar build/hadoop-examples-1.2.0-SNAPSHOT.jar -Dtest.randomwrite.total_bytes=8 rw2
{code}
it fails with the following error:
{code}
java.lang.Exception: org.apache.hadoop.mapred.Counters$CountersExceededException: Error: Exceeded
limits on number of counters - Counters=120 Limit=120
{code}

Using the jar compiled with branch-1 when running in a hadoop 2 cluster completes without
any error and don't see the counter. Interestingly there were two more custom counters in
the same job that are incremented and they are visible. The difference is that they use the
method 
Reporter.incrCounter(Enum<?> key, long amount).

Compiled this against 2.x/trunk and ran it. The job did fail with the expected counter exceeded
exception. So it seems to be a case of binary incompatibility between 1.x and 2.x.

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