sync.RWMutex模拟并发读写实例

Question

想用sync.RWMutex模拟一下并发读写场景下的用途，写了下面代码：

var (  
   useLock \= true  
  count \= 0  
  rwmutex \= sync.RWMutex{}  
)  
  
func main6() {  
   fmt.Println("本次执行是否使用 rwmutex? " \+ gconv.String(useLock))  
   waitGroup := sync.WaitGroup{}  
   waitGroup.Add(4)  
  
   go put(grand.Intn(100), &waitGroup)  
   go put(grand.Intn(100), &waitGroup)  
   go put(grand.Intn(100), &waitGroup)  
  
   go get(grand.Intn(50), &waitGroup)  
  
   waitGroup.Wait()  
   fmt.Println("并发写结束")  
  
   //最后读取等待并发组结束  
  readValue := make(chan int)  
   waitGroup.Add(1)  
   go read(readValue, &waitGroup)  
   v := <-readValue  
  fmt.Println("读取到count=" \+ gconv.String(v))  
  
}  
  
func get(num int, wait \*sync.WaitGroup) {  
   if useLock {  
      rwmutex.Lock()  
      defer rwmutex.Unlock()  
   }  
   defer wait.Done()  
   if count < num {  
      fmt.Println("get: can not get num:" \+ gconv.String(num) + " > count=" \+ gconv.String(count))  
   } else {  
      fmt.Println("get: can get num:" \+ gconv.String(num) + " < count=" \+ gconv.String(count))  
      count \= count \- num  
  }  
   fmt.Println("get: after get count=" \+ gconv.String(count))  
}  
func put(num int, wait \*sync.WaitGroup) {  
   if useLock {  
      rwmutex.Lock()  
      defer rwmutex.Unlock()  
   }  
   defer wait.Done()  
   fmt.Println("put: put num:" \+ gconv.String(num))  
   count \= count \+ num  
  fmt.Println("put: after put count=" \+ gconv.String(count))  
}  
func read(readValue chan int, wait \*sync.WaitGroup) {  
   if useLock {  
      rwmutex.RLock()  
      defer rwmutex.RUnlock()  
   }  
   defer wait.Done()  
   fmt.Println("read: read count=" \+ gconv.String(count))  
   readValue <- count  
}

问题：get put read方法不用rwmutex，打印的结果也没感受到数据错乱，如何改一下，体现出不能保证原子性？
以下是不用rwmutex打印结果：

本次执行是否使用 rwmutex? false
get: can not get num:43 > count=0
get: after get count=0
put: put num:35
put: after put count=35
put: put num:63
put: after put count=98
put: put num:28
put: after put count=126
并发写结束
read: read count=126
读取到count=126

以下是使用rwmutex打印结果：

本次执行是否使用 rwmutex? true
put: put num:47
put: after put count=47
get: can get num:17 < count=47
get: after get count=30
put: put num:66
put: after put count=96
put: put num:13
put: after put count=109
并发写结束
read: read count=109
读取到count=109