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https://issues.apache.org/jira/browse/HBASE-21991?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sean Busbey updated HBASE-21991:
--------------------------------
Release Note: The class LossyCounting was unintentionally marked Public but
was never intended to be part of our public API. This oversight has been
corrected and LossyCounting is now marked as Private and going forward may be
subject to additional breaking changes or removal without notice. If you have
taken a dependency on this class we recommend cloning it locally into your
project before upgrading to this release. (was: Moving IA.Public class
LossyCounting to IA.Private.)
> 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
> Fix For: 3.0.0, 1.5.0, 2.2.0, 1.4.10, 2.3.0
>
> Attachments: hbase-21991.addendum.patch,
> hbase-21991.branch-1.001.patch, hbase-21991.branch-1.002.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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