c# HttpClient每几个调用返回一次错误500(内部服务器错误)

我的web应用程序使用HttpClient连接到后端。通常它可以工作，但是每10=15次调用就会出现一次错误500。当页面重新加载时，一切正常。错误出现在与HttpClient对象进行后端连接的代码中。我的web应用程序使用Unity作为IOC。

我在当前代码之前做了一些试验:HttpClientHelper有静态字段static HttpClient httpClient，没有在代码

中处理

但仍然出现错误500。

BUT:当我做很多来自外部应用程序的调用，如提琴手，错误没有出现。我做了大约150个快速呼叫，没有出现任何错误。

UPDATE1:

我对fiddler的请求是:

GET http://www.zzz.com/methodA HTTP/1.1
Authorization: Basic **********************
Accept: application/json
Accept-Language: en-US, en; q=0.5
Host:www.zzz.com

fiddler的响应是:

HTTP/1.1 500 Internal Server Error
Cache-Control: no-cache
Pragma: no-cache
Content-Type: application/json; charset=utf-8
Expires: -1
Server: Microsoft-IIS/8.0
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
Date: Tue, 06 Sep 2016 14:06:34 GMT
Content-Length: 36
{"Message":"An error has occurred."}

更新2:

我改变了代码，所以httpClient是一个静态属性。但问题还是一样的。HttpClientHelper类的代码是从async/await开始的，也许这是一个问题?

UPDATE3:我创建了一个新的帖子，它更详细:https://stackoverflow.com/questions/39367225/how-to-syncronize-static-valiable-inside-async-await-methods-httpclient-error-5欢迎你继续;)

我当前的连接类是:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Threading.Tasks;
using System.Web;
namespace MicrositeEngine.Common.Helpers
{
    /// <summary>
    /// Helper class for http calls
    /// </summary>
    public class HttpClientHelper
    {
        private IDictionary<string, string> _customHeaders { get; set; }
        public HttpClientHelper() { }
        public HttpClientHelper(IDictionary<string, string> customHeader)
        {
            _customHeaders = customHeader;
        }
        /// <summary>
        /// Asychronously download string data from given url
        /// </summary>
        /// <param name="url">Place for download string from</param>
        /// <returns>String data downloaded from url</returns>
        public async Task<string> GetStringAsync(string url)
        {
            HttpResponseMessage response = null;
            using (HttpClient httpClient = CreateHttpClient())
            {
                httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(HttpRequestConsts.ContentTypeJson));
                httpClient.DefaultRequestHeaders.Add("Connection", "keep-alive");
                httpClient.DefaultRequestHeaders.Add("Accept-Language", "en-US,en;q=0.5");
                response = await httpClient.GetAsync(url).ConfigureAwait(true);
                response.EnsureSuccessStatusCode();
            }
            return await response.Content.ReadAsStringAsync().ConfigureAwait(true);
        }
        /// <summary>
        /// Asychronously download byte array data from given url
        /// </summary>
        /// <param name="url">Place for download byte array from</param>
        /// <returns>Byte array data downloaded from url</returns>
        public async Task<byte[]> GetByteArrayAsync(string url)
        {
            HttpResponseMessage response = null;
            using (HttpClient httpClient = CreateHttpClient())
            {
                httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(HttpRequestConsts.ContentTypeJson));
                httpClient.DefaultRequestHeaders.Add("Connection", "keep-alive");
                httpClient.DefaultRequestHeaders.Add("Accept-Language", "en-US,en;q=0.5");
                response = await httpClient.GetAsync(url).ConfigureAwait(true);
                response.EnsureSuccessStatusCode();
            }
            return await response.Content.ReadAsByteArrayAsync().ConfigureAwait(true);
        }

        private HttpClient CreateHttpClient()
        {
            var clientHandler = new HttpClientHandler { };
            var client = new HttpClient(clientHandler);
            if (_customHeaders != null)
            {
                foreach (var item in _customHeaders)
                {
                    client.DefaultRequestHeaders.Add(item.Key, item.Value);
                }
            }
            client.MaxResponseContentBufferSize = 2147483647; //max possible value
            return client;
        }
    }
}