UnixNano Collision

main.go

/*
	UnixNano method has time-sensitivity between 40-500 nanoseconds.
	Likely to produce the same output for few simultaneous goroutines within
	the same period. Do not rely on UnixNano result being unique.
*/
package main

import (
	"fmt"
	"sync"
	"time"
)

const tryingCount = 150

func main() {
	var timeStampsSlice []int64 // storage of unix timestamps

	var wg sync.WaitGroup

	var mt sync.Mutex

	for z := 0; z < 100; z++ {
		for i := 0; i < tryingCount; i++ {
			wg.Add(1)

			go func() {
				tf := time.Now().UnixNano()

				mt.Lock()
				timeStampsSlice = append(timeStampsSlice, tf)
				mt.Unlock()

				wg.Done()
			}()
		}
		wg.Wait()

		if mapReturn := duplicateCount(timeStampsSlice); len(mapReturn) != 0 {
			for timeStamp, repeatCount := range mapReturn {
				fmt.Printf("Timestamp : %d repeated %d times. \n", timeStamp, repeatCount)
			}
		}

		timeStampsSlice = timeStampsSlice[:0]
	}
}

func duplicateCount(list []int64) map[int64]int {
	duplicateFrequency := make(map[int64]int)

	for _, item := range list {
		_, exist := duplicateFrequency[item]

		if exist {
			duplicateFrequency[item]++
		} else {
			duplicateFrequency[item] = 1
		}
	}

	for k, v := range duplicateFrequency {
		if v == 1 {
			delete(duplicateFrequency, k)
		}
	}

	return duplicateFrequency
}