Use "HdrHistogram" and "LatencyUtils" to replace old algorithm in StatCalculator

[shaqianqian]

Hello All,
I am trying to calculate the percentiles of response times with help of
"HdrHistrogram and LatencyUtils",

    public void addValue(Long val) {
        sum += val;
        latencyStats.recordLatency(val*1000000);
        latencyStats.getIntervalHistogramInto(intervalHistogram);
        histogram.add(intervalHistogram);
        max = Math.max(val, max);
        min = Math.min(val, min);
    }
    public Long getPercentPoint(double percent) {
        return histogram.getValueAtPercentile(100.0 * percent);
    }

But I found the percentiles in 99% line is bigger than the maximum of
response time which is abnormal. (I compute maximum time by normal math
method, not by Histrogram)
Could you give me some explanation on why this happens ?

Thank you for your help.

Regards

Thanks