[英]HttpClient on WebApi is extremely slow
我正在使用 ASP.NET WebApi (ApiController) 為我的應用程序實現一個代理,並使用 HttpClient 在我的授權 header 下發出請求。它工作正常,但速度非常慢。 下面是主要代碼,然后是全局初始化(帶DefaultConnectionLimit)和web.config相關的一塊。
如您所見,我已經在實際請求中使用沒有代理和HttpCompletionOption.ResponseHeadersRead的靜態/共享 HttpClient object。 這個 WebApi 端點被並行調用,工作正常。
整個代碼運行速度足夠快,但是當我使用 ResponseHeadersRead async 時,HttpRequestMessage 被返回並且主體的 rest 被下載並直接流式傳輸到客戶端/調用者。
這是顯示問題的視頻。
public class ProxyController : ApiController
{
private const string BASE_URL = "https://developer.api.autodesk.com";
private const string PROXY_ROUTE = "api/viewerproxy/";
// HttpClient has been designed to be re-used for multiple calls. Even across multiple threads.
// https://stackoverflow.com/questions/22560971/what-is-the-overhead-of-creating-a-new-httpclient-per-call-in-a-webapi-client
private static HttpClient _httpClient;
[HttpGet]
[Route(PROXY_ROUTE + "{*.}")]
public async Task<HttpResponseMessage> Get()
{
if (_httpClient == null)
{
_httpClient = new HttpClient(new HttpClientHandler()
{
UseProxy = false,
Proxy = null
});
_httpClient.BaseAddress = new Uri(BASE_URL);
}
string url = Request.RequestUri.AbsolutePath.Replace(PROXY_ROUTE, string.Empty);
string absoluteUrl = url + Request.RequestUri.Query;
try
{
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, absoluteUrl);
request.Headers.Add("Authorization", "Bearer " + AccessToken);
HttpResponseMessage response = await _httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);
return response;
}
catch (Exception e)
{
return new HttpResponseMessage(System.Net.HttpStatusCode.InternalServerError);
}
}
}
Global.asax,雖然我不認為是連接限制的問題,因為所有請求都已處理,但太慢了......
public class Global : System.Web.HttpApplication
{
protected void Application_Start(object sender, EventArgs e)
{
GlobalConfiguration.Configure(Config.WebApiConfig.Register);
ServicePointManager.UseNagleAlgorithm = true;
ServicePointManager.Expect100Continue = false;
ServicePointManager.CheckCertificateRevocationList = true;
ServicePointManager.DefaultConnectionLimit = int.MaxValue;
}
}
和部分 Web.Config
<system.web>
<compilation debug="true" targetFramework="4.6" />
<httpRuntime targetFramework="4.6" maxRequestLength="2097151" requestLengthDiskThreshold="16384" requestPathInvalidCharacters="<,>,*,%,&,\,?" />
</system.web>
通過刪除web.config的<system.diagnostics>
部分來解決。 看來這導致了過多的輸出並減慢了所有HttpClient
請求的速度。
作為記錄,這是我正在使用的代碼,導致所有HttpClient.SendAsync
調用速度緩慢。 但這對於跟蹤連接問題很有用:-)
<system.diagnostics>
<sources>
<source name="System.Net" tracemode="protocolonly" maxdatasize="1024">
<listeners>
<add name="System.Net"/>
</listeners>
</source>
<source name="System.Net.Cache">
<listeners>
<add name="System.Net"/>
</listeners>
</source>
<source name="System.Net.Http">
<listeners>
<add name="System.Net"/>
</listeners>
</source>
</sources>
<switches>
<add name="System.Net" value="Verbose"/>
<add name="System.Net.Cache" value="Verbose"/>
<add name="System.Net.Http" value="Verbose"/>
<add name="System.Net.Sockets" value="Verbose"/>
<add name="System.Net.WebSockets" value="Verbose"/>
</switches>
<sharedListeners>
<add name="System.Net"
type="System.Diagnostics.TextWriterTraceListener"
initializeData="network.log"
/>
</sharedListeners>
<trace autoflush="true"/>
</system.diagnostics>
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