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https://issues.apache.org/jira/browse/HBASE-21991?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16796657#comment-16796657
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Hadoop QA commented on HBASE-21991:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | {color:blue} reexec {color} | {color:blue}  0m  
0s{color} | {color:blue} Docker mode activated. {color} |
| {color:red}-1{color} | {color:red} patch {color} | {color:red}  0m  7s{color} 
| {color:red} HBASE-21991 does not apply to branch-1. Rebase required? Wrong 
Branch? See https://yetus.apache.org/documentation/0.8.0/precommit-patchnames 
for help. {color} |
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|| Subsystem || Report/Notes ||
| JIRA Issue | HBASE-21991 |
| JIRA Patch URL | 
https://issues.apache.org/jira/secure/attachment/12963047/hbase-21991.branch-1.001.patch
 |
| Console output | 
https://builds.apache.org/job/PreCommit-HBASE-Build/16436/console |
| Powered by | Apache Yetus 0.8.0   http://yetus.apache.org |


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> Fix MetaMetrics issues - [Race condition, Faulty remove logic], few 
> improvements
> --------------------------------------------------------------------------------
>
>                 Key: HBASE-21991
>                 URL: https://issues.apache.org/jira/browse/HBASE-21991
>             Project: HBase
>          Issue Type: Bug
>          Components: Coprocessors, metrics
>            Reporter: Sakthi
>            Assignee: Sakthi
>            Priority: Major
>         Attachments: hbase-21991.branch-1.001.patch, 
> hbase-21991.master.001.patch, hbase-21991.master.002.patch, 
> hbase-21991.master.003.patch, hbase-21991.master.004.patch, 
> hbase-21991.master.005.patch, hbase-21991.master.006.patch
>
>
> Here is a list of the issues related to the MetaMetrics implementation:
> +*Bugs*+:
>  # [_Lossy counting for top-k_] *Faulty remove logic of non-eligible meters*: 
> Under certain conditions, we might end up storing/exposing all the meters 
> rather than top-k-ish
>  # MetaMetrics can throw NPE resulting in aborting of the RS because of a 
> *Race Condition*.
> +*Improvements*+:
>  # With high number of regions in the cluster, exposure of metrics for each 
> region blows up the JMX from ~140 Kbs to 100+ Mbs depending on the number of 
> regions. It's better to use *lossy counting to maintain top-k for region 
> metrics* as well.
>  # As the lossy meters do not represent actual counts, I think, it'll be 
> better to *rename the meters to include "lossy" in the name*. It would be 
> more informative while monitoring the metrics and there would be less 
> confusion regarding actual counts to lossy counts.



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