考虑使用VS2015编写的控制台应用程序上的以下代码:

using System;
using System.Threading.Tasks;

public class Example
{
    public static void Main()
    {
        Console.WriteLine("Wait please....");
        DateTime time1 = DateTime.Now;
        Task task1 = MyAsyncFun1();
        Task task2 = MyAsyncFun2();
        task1.Wait();
        task2.Wait();
        DateTime time2 = DateTime.Now;
        Console.WriteLine("time elapsed: " + 
        (time2 -  time1).TotalSeconds);
        Console.ReadLine();
    }
    private static async Task MyAsyncFun1()
    {
        await Task.Yield();
        System.Threading.Thread.Sleep(2000);
    }
    private static async Task MyAsyncFun2()
    {
        await Task.Yield();
        System.Threading.Thread.Sleep(2000);
    }
}

有两个方法是异步调用的，所有方法都工作得很好，“经过的时间”不超过2秒，因为执行是并行的。

但是当我在一个ApiController的acion方法中编写了如下代码时:

public class MyController : ApiController
{
    private static async Task MyAsyncFun1()
    {
        await Task.Yield();
        System.Threading.Thread.Sleep(2000);
    }
    private static async Task MyAsyncFun2()
    {
        await Task.Yield();
        System.Threading.Thread.Sleep(2000);
    }
    public async Task<ApiResult> MyAction([FromBody] Mymodel model)
    {
        DateTime time1 = DateTime.Now;
        Task task1 = MyAsyncFun1();
        Task task2 = MyAsyncFun2();
        task1.Wait();
        task2.Wait();
        DateTime time2 = DateTime.Now;
        double d=(time2 - time1).TotalSeconds;
        return .....;
    }
}

task1.wait()语句的执行无限期挂起。