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From "Sascha Coenen (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HADOOP-11182) GraphiteSink emits wrong timestamps
Date Thu, 09 Oct 2014 11:59:33 GMT
Sascha Coenen created HADOOP-11182:
--------------------------------------

             Summary: GraphiteSink emits wrong timestamps
                 Key: HADOOP-11182
                 URL: https://issues.apache.org/jira/browse/HADOOP-11182
             Project: Hadoop Common
          Issue Type: Bug
    Affects Versions: 2.5.1, 2.5.0
            Reporter: Sascha Coenen


the org.apache.hadoop.metrics2.sink.GraphiteSink class emits metrics at the configured time
period, but the timestamps written only change every 128 seconds, even it the configured time
period in the configuration file is much shorter.

This is due to a bug in line 93:

{code:java}
092            // Round the timestamp to second as Graphite accepts it in such format.
093            int timestamp = Math.round(record.timestamp() / 1000.0f);
{code}

The timestamp property is a long and is divided by a float which yields a result that is not
precise enough and yields same valued results for timestamps that lie up to 128 seconds apart.
Also, the result is then written into an int variable.

One solution would be to divide by 1000.0d, but the best fix would be to not even convert
to a decimal format in the first place. Instead one could replace the line with the following:

{code:java}
   long timestamp = record.timestamp() / 1000L;
{code}



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