map access.go

package main

import (
	"log"
	"math/rand"
	"runtime"
	"time"
	"sync/atomic"
)



func main() {
	result := make([]int, 1000)
	m := make(map[int]int)
	for i := 0; i < 500; i++ {
		m[i] = rand.Int()
	}
	var running int64 = 1
	log.Println("start running")
	for i := 0; i < 100; i++ {
		go func(index int) {
			r := rand.New(rand.NewSource(int64(index)))
			for atomic.LoadInt64(&running) == 1 {
				result[index] = m[r.Intn(1000)]
			}
		} (i)
	}
	/*go func() {
		r := rand.New(rand.NewSource(1001))
		for atomic.LoadInt64(&running) == 1 {
			m[r.Intn(1000)] = r.Int()
		}
	}()*/
	time.Sleep(time.Second)
	log.Println(runtime.NumGoroutine())
	time.Sleep(time.Second)
	atomic.SwapInt64(&running, 0)
	time.Sleep(time.Second)
	log.Println(runtime.NumGoroutine())
}