[AMBARI-23008] AMS: SUM downsampling function works incorrectly

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 2.6.1
• Fix Version/s: 2.6.2
• Component/s: ambari-metrics
• Labels: pull-request-available
• Assignee: Aravindan Vijayan
• Reporter: Aravindan Vijayan
• Created: 15/Feb/18 20:25
• Updated: 22/May/18 21:40
• Resolved: 20/Feb/18 17:14

Description

AMS, by default does not sum up across time dimension. However, there are certain metric cases where this is useful.

Aggregation Scenario - How it should work

Let's say in Host H1 - the metric values for 'topology.streamline-2-test-clone.3-KAFKA.TASK1.--emit-count.STREAM1' are 1,1,0,1,2 in time 10:01 to 10:05 (1 minute values) respectively

And, in Host H2 - the metric values for the same metric are 1,0,2,2,1 respectively

AMS will first aggregate across hosts. 'Sum' aggregation -> 2,1,2,3,3 (10:01 - 10:05) and then across time (downsampling) for larger windows. In time based downsampling, the 'sum' value will be 11 (2 + 1 + 2 + 3 + 3) at 10:05.

Also, such metrics should not be interpolated, because the injected values will cause wrong summed up values.

 Work
A new custom downsampler was added which implements the above logic.

Issue Links

• links to: GitHub Pull Request #380
• links to: GitHub Pull Request #382