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https://issues.apache.org/jira/browse/HBASE-15160?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15239224#comment-15239224
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Yu Li commented on HBASE-15160:
-------------------------------

Back to this JIRA. Confirmed that under heavy random read(get) load, the 
current patch using BlockingQueue to collect metrics will cause *~3%* 
performance regression. Benchmarking with the JMH case Enis wrote up we could 
see using MutableHistogram is less expensive thus promising. Will re-implement 
with MutableHistogram and see how it works out.

[~enis], mind if I take this one back? Or you already have something in 
progress? Thanks.

> Put back HFile's HDFS op latency sampling code and add metrics for monitoring
> -----------------------------------------------------------------------------
>
>                 Key: HBASE-15160
>                 URL: https://issues.apache.org/jira/browse/HBASE-15160
>             Project: HBase
>          Issue Type: Sub-task
>    Affects Versions: 2.0.0, 1.1.2
>            Reporter: Yu Li
>            Assignee: Yu Li
>         Attachments: HBASE-15160.patch, HBASE-15160_v2.patch, 
> HBASE-15160_v3.patch
>
>
> In HBASE-11586 all HDFS op latency sampling code, including fsReadLatency, 
> fsPreadLatency and fsWriteLatency, have been removed. There was some 
> discussion about putting them back in a new JIRA but never happened. 
> According to our experience, these metrics are useful to judge whether issue 
> lies on HDFS when slow request occurs, so we propose to put them back in this 
> JIRA, and add the metrics for monitoring as well.



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