Two important configuration parameters of HDR (High Dynamic Range) histogram are 1) integer value range and 2) the value precision.
For example, let's assume that the range is 0 - 3,600,000,000 and the value precision = 3 ( (means that the accuracy of any value within the range will be better than 1/1000 of the value) Under these settings HDR histogram can track and analyze the counts of observed response times ranging between 1 microsecond and 1 hour in magnitude with the following resolutions [1]: 1 microsecond resolution up to 1 millisecond, 1 millisecond (or better) resolution up to one second 1 second (or better) resolution up to 1,000 seconds. 3.6 seconds (or better) resolution up to 1 hour The memory footprint HDR depends on the dynamic range and precision chosen (As Isuru already pointed for a given dynamic range and precision the memory foot print is fixed). There is a way to compute the memory foot print using these values [1]. [1] https://github.com/HdrHistogram/HdrHistogram On Fri, Oct 14, 2016 at 9:33 AM, Isuru Perera <isu...@wso2.com> wrote: > Hi, > > In Carbon Metrics [1], the TImers and Histograms use the default reservoir > provided by the Dropwizard Metrics [2] library. > > Currently there is no support to change this reservoir implementation in > Carbon Metrics. Therefore we are working on supporting a set of reservoirs > in Carbon Metrics. > > The HdrHistogram [3] is a popular histogram implementation and it has lot > of useful features for us. For more info, see [4]. One major advantage for > us is that HDR Histogram maintains a fixed cost in both space and time. > > When using HdrHistogram as reservoir, we can also a solve a problem with > the default Exponentially Decaying Reservoir when publishing metrics events > to WSO2 Data Analytics Server. The problem is explained in [5]. With HDR > Histogram, we can reset the snapshot when reporting to WSO2 DAS. > > We are going to integrate HDR Histogram into the next Carbon Metrics > release, which is based on Carbon 5.x > > We don't have plans to do any release of Carbon Metrics based on Carbon > 4.x. If anyone needs the HDR Histogram as a reservoir, we'll be able to do > changes in 1.x.x [6] branch and do a release. > > Thanks! > > Best Regards, > > [1] https://github.com/wso2/carbon-metrics > [2] http://metrics.dropwizard.io > [3] https://github.com/HdrHistogram/HdrHistogram > [4] http://hdrhistogram.github.io/HdrHistogram/ > [5] http://taint.org/2014/01/16/145944a.html > [6] https://github.com/wso2/carbon-metrics/branches > > -- > Isuru Perera > Associate Technical Lead | WSO2, Inc. | http://wso2.com/ > Lean . Enterprise . Middleware > > about.me/chrishantha > Contact: +IsuruPereraWSO2 <https://www.google.com/+IsuruPereraWSO2/about> > -- Malith Jayasinghe WSO2, Inc. (http://wso2.com) Email : mali...@wso2.com Mobile : 0770704040 Lean . Enterprise . Middleware
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