[jira] [Commented] (HBASE-3614) Expose per-region request rate metrics

["stack (Commented) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-3614?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13255304#comment-13255304 ] 

stack commented on HBASE-3614:
------------------------------

FYI 100 chars per line max and space around operators (this won't fly: "cfSetConsistent?cfSet:null")

I like how you are removing metrics stuff from HRegion out to a region scoped metrics class.

'+public class RegionMetrics {' needs a class comment saying what its all about.   Does the class need to be public?  Can it be scoped to this package only?

Collect all the data members at the top of the class. Thats whats usually done in this code base.

So put the tablename etc. in RegionMetric before the constructor etc. rather than after.

Does this need to be public generateRegionMetricsPrefix?

What do these new metrics look like?  Is this all it takes to expose them?

Some regionnames are going to be really long.  Should you use the region encoded name instead of the full name?  Do you think we even need the table name as prefix?

Good stuff Elliott.
                
> Expose per-region request rate metrics
> --------------------------------------
>
>                 Key: HBASE-3614
>                 URL: https://issues.apache.org/jira/browse/HBASE-3614
>             Project: HBase
>          Issue Type: Improvement
>          Components: metrics, regionserver
>            Reporter: Gary Helmling
>            Assignee: Elliott Clark
>            Priority: Minor
>         Attachments: HBASE-3614-0.patch, HBASE-3614-1.patch
>
>
> We currently export metrics on request rates for each region server, and this can help with identifying uneven load at a high level. But once you see a given server under high load, you're forced to extrapolate based on your application patterns and the data it's serving what the likely culprit is.  This can and should be much easier if we just exported request rate metrics per-region on each server.
> Dynamically updating the metrics keys based on assigned regions may pose some minor challenges, but this seems a very valuable diagnostic tool to have available.

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