c# - 执行 client.SendAsync 时出现 HttpRequestException

Question

突然间，这段通常有效的代码开始抛出 HttpRequestException 错误。在日志中，我看到请求实际上是在抛出错误之前 1 分 35 秒发送的。会不会是超时问题？

代码如下:

private async Task<HttpResponseMessage> RunRequest(HttpRequestMessage request)
{            
    var client = new HttpClient();
    var response = await client.SendAsync(request).ConfigureAwait(false);              
    return response;           
}

这是调用者(可能有 10K 到 50K 项):

int counter = 0;
var tasks = items.Select(async i =>
{
    if (await RunRequest(CreateRequest(i)))
        counter++
}).ToList();

if (tasks.Any())
{ 
    await Task.WhenAll(tasks);
}

这里是错误:

System.Net.Http.HttpRequestException: An error occurred while sending the request. ---> System.Net.WebException: The request was aborted: The request was canceled.
        at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
        at System.Net.Http.HttpClientHandler.GetResponseCallback(IAsyncResult ar)
        --- End of inner exception stack trace ---
        at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
        at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
        at MyClass.<RunRequest>d__c.MoveNext()
        --- End of inner exception stack trace ---
        at MyClass.<RunRequest>d__c.MoveNext()
        --- End of stack trace from previous location where exception was thrown ---
        at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
        at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
        at MyClass.<RunRequest>d__0.MoveNext()

Task.WhenAll 是否有限制？

Answer 1

如果您的所有请求都针对同一个域，那么您需要将此添加到您的“Web.config”文件(默认仅为 2):

<configuration>
    <system.net>
        <connectionManagement>
            <add address="*" maxconnection="100" />
        </connectionManagement>
    <system.net>
<configuration>

并且您已经在等待每个 RunRequest 依次连续地等待，因此实际上没有任何并行运行 - 并且您的 Task.WhenAll 应该抛出异常，因为您给它一个 HttpResponseMessage 列表而不是一个 Task 列表。

RunRequest 不返回 bool，那么您如何在 if 中使用它？

...这段代码有太多错误...