Merge pull request #1034 from lin-jianjun/1.5

远程调用次数变量读取未使用原子操作

protocol/dubbo/dubbo_invoker.go

@@ -87,7 +87,7 @@ func (di *DubboInvoker) Invoke(ctx context.Context, invocation protocol.Invocati
 		err    error
 		result protocol.RPCResult
 	)
-	if di.reqNum < 0 {
+	if atomic.LoadInt64(&di.reqNum) < 0 {
 		// Generally, the case will not happen, because the invoker has been removed
 		// from the invoker list before destroy,so no new request will enter the destroyed invoker
 		logger.Warnf("this dubboInvoker is destroyed")