time package problem

Makefile

include $(GOROOT)/src/Make.inc

TARG=testtickers
GOFILES=testtickers.go

include $(GOROOT)/src/Make.cmd

testtickers.go

package main

import (
	"time"
	"os"
	"fmt"
	"rand"
)

const (
	second = 1000*1000*1000
	minute = second * 60
	maxtick = second*10
	mintick = second/2
)

func newticktime() int64 {
	t := rand.Int63n(maxtick)
	for t < mintick {
		t = rand.Int63n(maxtick)
	}
	return t
}

func startticker(t int64, done chan bool) {
	ticker := time.NewTicker(t)
	next := time.Nanoseconds() + t
	fmt.Printf("Ticker of %f seconds at %s\n", float(t)/second, time.LocalTime().String())
	<-ticker.C
	diff := time.Nanoseconds()-next
	fmt.Printf("Ticker of %f seconds, skew of %f at %s\n", float(t)/second, float(diff)/second, time.LocalTime().String())
	if diff > second * 5 {
		fmt.Printf("Fatal: skew of more than 5 seconds: %f\n", float(diff)/second)
		os.Exit(1)
	}
	ticker.Stop()
	time.Sleep(newticktime())
	done <-true
	return
}

func main() {
	rand.Seed(time.Nanoseconds())
	parallel := 4
	numtests := 500
	done := make(chan bool, parallel)
	go func() {
		ch := time.Tick(minute*15)
		fmt.Printf("Ticker of %d seconds at %s\n", (minute*15)/second, time.LocalTime().String())
		ch2 := time.Tick(minute)
		fmt.Printf("Ticker of %d seconds at %s\n", minute/second, time.LocalTime().String())
		for {
			next := time.Nanoseconds() + minute*15
			next2 := time.Nanoseconds() + minute
			select {
			case <-ch:
				diff := time.Nanoseconds() - next
				fmt.Printf("Ticker of %f seconds, skew of %f at %s\n", float(minute*15)/second, float(diff)/second, time.LocalTime().String())
				break
			case <-ch2:
				diff := time.Nanoseconds() - next2
				fmt.Printf("Ticker of %f seconds, skew of %f at %s\n", float(minute)/second, float(diff)/second, time.LocalTime().String())
				break
			}
		}
	}()
	for i:=0; i<=parallel; i++ {
		go startticker(newticktime(), done)
	}
	for i:=0; i<=numtests-parallel; i++ {
		<-done
		go startticker(newticktime(), done)
	}
	for i:=0; i<=parallel; i++ {
		<-done
	}
	os.Exit(0)
}