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https://issues.apache.org/jira/browse/HBASE-6261?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13417302#comment-13417302
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Andrew Wang commented on HBASE-6261:
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It'd be these files from hadoop-common:
* src/main/java/org/apache/hadoop/metrics2/lib/MutableQuantiles.java
* src/main/java/org/apache/hadoop/metrics2/lib/Quantiles.java
* src/main/java/org/apache/hadoop/metrics2/util/SampleQuantiles.java
{{wc -l}} reports it's 534 lines across those three files, heavily commented of
course. {{MutableQuantiles}} is a hadoop2 metrics2 interface for
SampleQuantiles, and might need to be modified for use in HBase. I haven't
looked at what Elliot's done for HBASE-4050 yet.
> Better approximate high-percentile percentile latency metrics
> -------------------------------------------------------------
>
> Key: HBASE-6261
> URL: https://issues.apache.org/jira/browse/HBASE-6261
> Project: HBase
> Issue Type: New Feature
> Reporter: Andrew Wang
> Assignee: Andrew Wang
> Labels: metrics
> Attachments: Latencyestimation.pdf
>
>
> The existing reservoir-sampling based latency metrics in HBase are not
> well-suited for providing accurate estimates of high-percentile (e.g. 90th,
> 95th, or 99th) latency. This is a well-studied problem in the literature (see
> [1] and [2]), the question is determining which methods best suit our needs
> and then implementing it.
> Ideally, we should be able to estimate these high percentiles with minimal
> memory and CPU usage as well as minimal error (e.g. 1% error on 90th, or .1%
> on 99th). It's also desirable to provide this over different time-based
> sliding windows, e.g. last 1 min, 5 mins, 15 mins, and 1 hour.
> I'll note that this would also be useful in HDFS, or really anywhere latency
> metrics are kept.
> [1] http://www.cs.rutgers.edu/~muthu/bquant.pdf
> [2] http://infolab.stanford.edu/~manku/papers/04pods-sliding.pdf
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