package main

import (
	"fmt"
	"sync"
	"sync/atomic"
)

func main() {
	var wg sync.WaitGroup
	var counter int64 // 注意必须是 int64/uint64 等特定类型

	for i := 0; i < 1000; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			for j := 0; j < 1000; j++ {
				atomic.AddInt64(&counter, 1)
			}
		}()
	}

	wg.Wait()
	fmt.Println("期待的结果:", 1000*1000)
	fmt.Println("实际结果:", counter)
}