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https://issues.apache.org/jira/browse/HBASE-11586?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14074868#comment-14074868
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Andrew Purtell commented on HBASE-11586:
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Do we need the dynamic schema metrics that these block read and write path 
measurements feed? If not we could open a 0.94 specific JIRA to remove them. 
Then this change can be backported. We could do the work with two commits like 
that perhaps. 

> HFile's HDFS op latency sampling code is not used
> -------------------------------------------------
>
>                 Key: HBASE-11586
>                 URL: https://issues.apache.org/jira/browse/HBASE-11586
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.98.4
>            Reporter: Andrew Purtell
>            Assignee: Andrew Purtell
>             Fix For: 0.99.0, 0.98.5, 2.0.0
>
>         Attachments: HBASE-11586.patch, HBASE-11586.patch
>
>
> HFileReaderV2 calls HFile#offerReadLatency and HFileWriterV2 calls 
> HFile#offerWriteLatency but the samples are never retrieved. There are no 
> callers of HFile#getReadLatenciesNanos, HFile#getWriteLatenciesNanos, and 
> related. The three ArrayBlockingQueues we are using as sample buffers in 
> HFile will fill quickly and are never drained. 
> There are also no callers of HFile#getReadTimeMs or HFile#getWriteTimeMs, and 
> related, so we are incrementing a set of AtomicLong counters that will never 
> be read nor reset.
> We are calling System.nanoTime in block read and write paths twice but not 
> utilizing the measurements.
> We should hook this code back up to metrics or remove it.
> We are also not using HFile#getChecksumFailuresCount anywhere but in some 
> unit test code.



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