[HADOOP-11182] GraphiteSink emits wrong timestamps

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.5.0, 2.5.1
• Fix Version/s: 2.6.0
• Assignee: Ravi Prakash
• Reporter: Sascha Coenen
• Created: 09/Oct/14 11:58
• Updated: 01/Dec/14 03:10
• Resolved: 15/Oct/14 22:54

Description

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:

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

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:

   long timestamp = record.timestamp() / 1000L;