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From "Stefan Podkowinski (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-13598) Active & Completed repair metrics
Date Thu, 22 Jun 2017 13:42:00 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-13598?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16059409#comment-16059409
] 

Stefan Podkowinski commented on CASSANDRA-13598:
------------------------------------------------

Using counters to represent ad-hoc values should be avoided whenever possible. In most cases
Gauges will be the better choice, but should only be read on request basis. 

Counters should be used for metrics only as monotonically increasing values. The issue with
metric consumers is that you can't be sure about the polling interval, which could be minutes.
In practice, you'd see at most a value "1" for the counter while it's polled once a minute,
while actually the counter has been going up and down a couple of times since it was last
polled.

A better approach would be having two counters "RepairJobsStarted" and "RepairJobsCompleted".
You'd only ever increase the counter. The number of active jobs could always be calculated
as delta between these two values. 


> Active & Completed repair metrics
> ---------------------------------
>
>                 Key: CASSANDRA-13598
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13598
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Cameron Zemek
>            Assignee: Cameron Zemek
>            Priority: Minor
>              Labels: repairs
>             Fix For: 4.x
>
>
> There are no metrics to monitor repairs run as co-ordinator. A number of metrics were
added with CASSANDRA-13531 but didn't include metrics to monitor if repair is running or how
many repairs have ran.
> |4.x|[patch|https://github.com/apache/cassandra/compare/instaclustr:trunk...instaclustr:13598-4.x]|
> |3.11|[patch|https://github.com/instaclustr/cassandra/compare/cassandra-3.11...instaclustr:13598-3.11]|
> |3.0|[patch|https://github.com/instaclustr/cassandra/compare/cassandra-3.0...instaclustr:13598-3.0]|
> |2.2|[patch|https://github.com/instaclustr/cassandra/compare/cassandra-2.2...instaclustr:13598-2.2]|



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