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https://issues.apache.org/jira/browse/HBASE-5533?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13230792#comment-13230792
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Shaneal Manek commented on HBASE-5533:
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Re line length: Ah, sorry about that. I was using 120 - fixed and will use 80
in the future.
Assign and declare together: Changed there (and in several other places). Will
assign with declaration where possible in the future.
Re timing overhead: Fixed it to cache calls to System.currentTimeMillis where
possible (see: CURRENT_TICK). Unfortunately, there is no good way to convert
between System.nanoTime and System.currentTimeMillis since the nanoTime epoch
is undefined. I've attached a benchmark showing that the overhead for
System.nanoTime() is ~20ns. At the rate we're calling it that should be
negligible.
Load: I couldn't measure a difference in performance with this code and without
it. I've used a similar technique to get latency distributions on a service
handling >10K requests/second with no trouble, fwiw.
TSDB/UI: Yep, TSDB should be able to interpret it as a standard metric (so you
can see you 95th percentile latencies over time, for example). I've uploaded a
screenshot so you can see what it looks like in the UI.
> Add more metrics to HBase
> -------------------------
>
> Key: HBASE-5533
> URL: https://issues.apache.org/jira/browse/HBASE-5533
> Project: HBase
> Issue Type: Improvement
> Affects Versions: 0.92.2, 0.94.0
> Reporter: Shaneal Manek
> Assignee: Shaneal Manek
> Priority: Minor
> Attachments: BlockingQueueContention.java, HBASE-5533-0.92-v4.patch,
> hbase-5533-0.92.patch, hbase5533-0.92-v2.patch, hbase5533-0.92-v3.patch,
> histogram_web_ui.png
>
>
> To debub/monitor production clusters, there are some more metrics I wish I
> had available.
> In particular:
> - Although the average FS latencies are useful, a 'histogram' of recent
> latencies (90% of reads completed in under 100ms, 99% in under 200ms, etc)
> would be more useful
> - Similar histograms of latencies on common operations (GET, PUT, DELETE)
> would be useful
> - Counting the number of accesses to each region to detect hotspotting
> - Exposing the current number of HLog files
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