[jira] [Created] (FLINK-6453) Web UI metrics charts should update only when a new data point is available

["Stephan Ewen (JIRA)" <ji...@apache.org>]

Stephan Ewen created FLINK-6453:
-----------------------------------

             Summary: Web UI metrics charts should update only when a new data point is available
                 Key: FLINK-6453
                 URL: https://issues.apache.org/jira/browse/FLINK-6453
             Project: Flink
          Issue Type: Sub-task
          Components: Webfrontend
            Reporter: Stephan Ewen


Metrics are pulled by the web server every 10 seconds by default.
The metric charts update more frequently and pull new events.

The charts assume that these are new data points, when in fact, they are mostly not. Drawing the same datapoint again to a different time makes all charts look stepwise, which is misleading:
There are some cases where metrics in fact increase stepwise (for example num events in bursty event channels) and currently there is no way to tell the difference.

A way around that would be to plot data points only if there are new data points. Identifying new data points can be done via attaching sequence numbers in the metrics handlers (incremented whenever the metrics are re-requested from TMs). The chart can ignore data points with the same sequence number.



--
This message was sent by Atlassian JIRA
(v6.3.15#6346)