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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-11586) HFile's HDFS op latency sampling code is not used
Date Fri, 25 Jul 2014 22:02:39 GMT

    [ https://issues.apache.org/jira/browse/HBASE-11586?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14075010#comment-14075010

Lars Hofhansl commented on HBASE-11586:

Honestly I am confused where we use/display these metrics. Are these the global fs{read|write}Latency
histograms that are shown on the region server UI and via JMX, or something else altogether.
I'll check the 0.94 in a bit.

> 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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