time.Now latency distribution

output

nothing 50: 11ns	75: 12ns	90: 13ns	99: 22ns	99.9: 169ns	99.99: 253ns	99.999: 15487ns	99.9999: 24362ns

whatever_test.go

package whatever

import (
	"fmt"
	"runtime"
	"sync"
	"testing"
	"time"

	"github.com/codahale/hdrhistogram"
)

func BenchmarkNow(b *testing.B) {
	startNanos := make([]int64, b.N)
	endNanos := make([]int64, b.N)

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		startNanos[i] = time.Now().UnixNano()
		endNanos[i] = time.Now().UnixNano()
	}

	b.StopTimer()
	recordLatencyDistribution("nothing", b.N, startNanos, endNanos)
}

func recordLatencyDistribution(name string, count int, startNanos []int64, endNanos []int64) {
	histogram := hdrhistogram.New(1, 1000000, 5)
	for i := 0; i < count; i++ {
		diff := endNanos[i] - startNanos[i]
		histogram.RecordValue(diff)
	}

	fmt.Printf("%s 50: %dns\t75: %dns\t90: %dns\t99: %dns\t99.9: %dns\t99.99: %dns\t99.999: %dns\t99.9999: %dns\n",
		name,
		histogram.ValueAtQuantile(50),
		histogram.ValueAtQuantile(75),
		histogram.ValueAtQuantile(90),
		histogram.ValueAtQuantile(99),
		histogram.ValueAtQuantile(99.9),
		histogram.ValueAtQuantile(99.99),
		histogram.ValueAtQuantile(99.999),
		histogram.ValueAtQuantile(99.9999))
}