Question

所以我构建了一个小程序来使用REST api，但它永远不会完成，因为没有收到任何数据。我是使用Async和wait命令的新手，所以我可能以某种方式弄错了。负责检索数据的线程在几秒钟后就会超时。网址本身虽然有效，但似乎没有例外。

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Threading.Tasks;

namespace Bot_Application1
{
    [Serializable]
    public class ConsumeFOAAS
    {
        private static HttpClient client = new HttpClient();
        private static String message = "empty";


        public String GetMessage()
        {
            RunAsync().Wait();
            return message;
        }


        static async Task RunAsync()
        {
            client.BaseAddress = new Uri("http://foaas.com/");
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("text/plain"));

            try
            {
                message = await GetProductAsync("/because/:Insultinator");
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }
        }


        static async Task<String> GetProductAsync(string path)
        {
            Debug.WriteLine("Inside GetProductAsync");
            String product = "empty";
            HttpResponseMessage response = await client.GetAsync(path); //<--This never finishes
            Debug.WriteLine("Response: " + response);
            if (response.IsSuccessStatusCode)
            {
                product = await response.Content.ReadAsStringAsync();
            }
            return product;
        }
    }
}

Answer 1

你不应该致电.Wait()。实现你想要的最好的等待是：

public async Task<String> GetMessage()
{   
    return await RunAsync();
}

并更改RunAsync功能：

static async Task<string> RunAsync() {

 client.BaseAddress = new Uri("http://foaas.com/");
 client.DefaultRequestHeaders.Accept.Clear();
 client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("text/plain"));

 try {
  return await GetProductAsync("/because/:Insultinator");
 } catch (Exception e) {
  Console.WriteLine(e.Message);
 }

}

Answer 2

死锁可能由任务管理器引起。尝试使用：

RunAsync().ConfigureAwait(false).Wait();

说明：http://blog.stephencleary.com/2012/07/dont-block-on-async-code.html

消费休息API死锁

2 个答案: