Iis ASP.NET WebAPI在初始阶段响应缓慢_Iis_Asp.net Web Api_Async Await_Task

Iis ASP.NET WebAPI在初始阶段响应缓慢

iis asp.net-web-api

Iis ASP.NET WebAPI在初始阶段响应缓慢,iis,asp.net-web-api,async-await,task,Iis,Asp.net Web Api,Async Await,Task,我创建了一个只引用Web API的空项目，并对这些简单API进行了调整，以查看其中一个异步作业是否存在任何性能差异和任何可能的挂起 public class TestController : ApiController { [HttpGet] [Route("Welcome")] public async Task<string> Welcome() { string r = await SlowMethod(); re

我创建了一个只引用Web API的空项目，并对这些简单API进行了调整，以查看其中一个异步作业是否存在任何性能差异和任何可能的挂起

public class TestController : ApiController
{
    [HttpGet]
    [Route("Welcome")]
    public async Task<string> Welcome()
    {
        string r = await SlowMethod();
        return r;
    }

    public async Task<string> SlowMethod()
    {
        Thread.Sleep(3000);
        return await Task.FromResult("data");
    }

    [HttpGet]
    [Route("WelcomeSync")]
    public string WelcomeSync()
    {
        string r = SlowSyncMethod();
        return r;
    }

    public string SlowSyncMethod()
    {
        Thread.Sleep(3000);
        return "data";
    }
}

Max是毫秒单位。由于

Thread.Sleep（3000）的结果，每个API每个请求至少需要3秒钟但其中一个或其中一些请求需要32秒才能完成
这是否意味着至少有一个异步作业出现挂起？如果有，绞刑的罪魁祸首是什么

更新
我曾经怀疑异步作业上存在挂起行为，但事实并非如此。只要改变测试顺序就可以得到相同的结果第一次测试在测试开始时总是很慢。这与异步与同步作业完全无关
无论如何，我试图在SlowMethod（）之间保留日志
使用Stopwatch
查看异步方法是否存在实际挂起，很快我发现异步和同步API上都没有挂起。日志总是打印“花了3秒钟”
迟到的是HTTP响应本身。速度慢有一个明显的特点

演出很快就开始失去节奏
它不断减速，直到达到30~40秒
之后，它开始从拖动性能中恢复
最终，它会在3秒钟内持续响应，直到结束

这些日志将帮助您更好地了解情况
2018-08-04 04:48:50.030 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 3. The result was "data"
2018-08-04 04:48:50.030 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 3. The result was "data"
2018-08-04 04:48:50.030 +09:00 [INF] CurrentThread 9, Context LeaseLifeTimeServiceProperty, Time passed 3. The result was "data"
2018-08-04 04:48:50.030 +09:00 [INF] CurrentThread 10, Context LeaseLifeTimeServiceProperty, Time passed 3. The result was "data"
2018-08-04 04:48:50.632 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 4. The result was "data"
2018-08-04 04:48:51.637 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 5. The result was "data"
2018-08-04 04:48:52.631 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 6. The result was "data"
2018-08-04 04:48:52.968 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 6. The result was "data"
2018-08-04 04:48:52.969 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 6. The result was "data"
2018-08-04 04:48:52.969 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 6. The result was "data"
2018-08-04 04:48:52.973 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 6. The result was "data"
2018-08-04 04:48:53.631 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 7. The result was "data"
2018-08-04 04:48:53.637 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 7. The result was "data"
2018-08-04 04:48:54.631 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 8. The result was "data"
2018-08-04 04:48:54.640 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 8. The result was "data"
2018-08-04 04:48:55.633 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 9. The result was "data"
2018-08-04 04:48:55.635 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 9. The result was "data"
2018-08-04 04:48:55.975 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 9. The result was "data"
2018-08-04 04:48:55.976 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 9. The result was "data"
2018-08-04 04:48:55.976 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 9. The result was "data"
2018-08-04 04:48:55.979 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 9. The result was "data"
2018-08-04 04:48:56.633 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 10. The result was "data"
2018-08-04 04:48:56.636 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 10. The result was "data"
2018-08-04 04:48:56.642 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 10. The result was "data"
.
.
.
2018-08-04 04:49:04.647 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 18. The result was "data"
2018-08-04 04:49:04.650 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 18. The result was "data"
2018-08-04 04:49:04.994 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 18. The result was "data"
2018-08-04 04:49:04.994 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 18. The result was "data"
2018-08-04 04:49:04.998 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 18. The result was "data"
2018-08-04 04:49:04.999 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 18. The result was "data"
2018-08-04 04:49:05.633 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 19. The result was "data"
2018-08-04 04:49:05.636 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 19. The result was "data"
2018-08-04 04:49:05.640 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 19. The result was "data"
2018-08-04 04:49:05.643 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 19. The result was "data"
2018-08-04 04:49:05.646 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 19. The result was "data"
2018-08-04 04:49:05.652 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 19. The result was "data"
2018-08-04 04:49:06.633 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 20. The result was "data"
2018-08-04 04:49:06.638 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 20. The result was "data"
2018-08-04 04:49:06.641 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 20. The result was "data"
2018-08-04 04:49:06.643 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 20. The result was "data"
2018-08-04 04:49:06.647 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 20. The result was "data"
2018-08-04 04:49:06.655 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 20. The result was "data"
.
.
.
2018-08-04 04:49:15.634 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 28. The result was "data"
2018-08-04 04:49:15.639 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 28. The result was "data"
2018-08-04 04:49:15.644 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 28. The result was "data"
2018-08-04 04:49:15.648 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 28. The result was "data"
2018-08-04 04:49:15.652 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 29. The result was "data"
2018-08-04 04:49:15.653 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 29. The result was "data"
2018-08-04 04:49:15.655 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 29. The result was "data"
2018-08-04 04:49:15.665 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 29. The result was "data"
2018-08-04 04:49:16.635 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 29. The result was "data"
2018-08-04 04:49:16.638 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 29. The result was "data"
2018-08-04 04:49:16.647 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 30. The result was "data"
2018-08-04 04:49:16.650 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 29. The result was "data"
2018-08-04 04:49:16.669 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 30. The result was "data"
2018-08-04 04:49:16.669 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 30. The result was "data"
2018-08-04 04:49:16.669 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 30. The result was "data"
2018-08-04 04:49:16.670 +09:00 [INF] CurrentThread 10, Context LeaseLifeTimeServiceProperty, Time passed 30. The result was "data"
2018-08-04 04:49:16.673 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 30. The result was "data"
2018-08-04 04:49:17.014 +09:00 [INF] CurrentThread 16, Context LeaseLifeTimeServiceProperty, Time passed 30. The result was 
2018-08-04 04:49:17.662 +09:00 [INF] CurrentThread 16, Context LeaseLifeTimeServiceProperty, Time passed 30. The result was "data"
2018-08-04 04:49:17.668 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 31. The result was "data"
2018-08-04 04:49:17.675 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 31. The result was "data"
2018-08-04 04:49:17.676 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 31. The result was "data"
2018-08-04 04:49:18.634 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 31. The result was "data"
2018-08-04 04:49:18.644 +09:00 [INF] CurrentThread 10, Context LeaseLifeTimeServiceProperty, Time passed 31. The result was "data"
2018-08-04 04:49:18.647 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 31. The result was "data"
2018-08-04 04:49:18.648 +09:00 [INF] CurrentThread 15, Context LeaseLifeTimeServiceProperty, Time passed 31. The result was "data"
2018-08-04 04:49:18.651 +09:00 [INF] CurrentThread 15, Context LeaseLifeTimeServiceProperty, Time passed 31. The result was "data"
2018-08-04 04:49:18.654 +09:00 [INF] CurrentThread 15, Context LeaseLifeTimeServiceProperty, Time passed 31. The result was "data"
2018-08-04 04:49:18.661 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 31. The result was "data"
2018-08-04 04:49:18.668 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 32. The result was "data"
2018-08-04 04:49:18.671 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 32. The result was "data"
2018-08-04 04:49:18.675 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 32. The result was "data"
2018-08-04 04:49:19.640 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 32. The result was "data"
2018-08-04 04:49:19.646 +09:00 [INF] CurrentThread 11, Context LeaseLifeTimeServiceProperty, Time passed 32. The result was "data"
2018-08-04 04:49:19.646 +09:00 [INF] CurrentThread 16, Context LeaseLifeTimeServiceProperty, Time passed 32. The result was "data"
2018-08-04 04:49:19.656 +09:00 [INF] CurrentThread 16, Context LeaseLifeTimeServiceProperty, Time passed 32. The result was "data"
2018-08-04 04:49:19.659 +09:00 [INF] CurrentThread 16, Context LeaseLifeTimeServiceProperty, Time passed 32. The result was "data"
2018-08-04 04:49:19.667 +09:00 [INF] CurrentThread 16, Context LeaseLifeTimeServiceProperty, Time passed 29. The result was "data"
2018-08-04 04:49:19.669 +09:00 [INF] CurrentThread 16, Context LeaseLifeTimeServiceProperty, Time passed 29. The result was "data"
2018-08-04 04:49:19.673 +09:00 [INF] CurrentThread 16, Context LeaseLifeTimeServiceProperty, Time passed 29. The result was "data"
2018-08-04 04:49:19.677 +09:00 [INF] CurrentThread 15, Context LeaseLifeTimeServiceProperty, Time passed 29. The result was "data"
2018-08-04 04:49:19.679 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 29. The result was "data"
2018-08-04 04:49:20.016 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 28. The result was "data"
2018-08-04 04:49:20.017 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 27. The result was "data"
2018-08-04 04:49:20.023 +09:00 [INF] CurrentThread 12, Context LeaseLifeTimeServiceProperty, Time passed 27. The result was "data"
.
.
.
2018-08-04 05:03:11.422 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 3. The result was "data"
2018-08-04 05:03:14.492 +09:00 [INF] CurrentThread 14, Context LeaseLifeTimeServiceProperty, Time passed 3. The result was "data"

IIS重新编译
，IIS应用程序池回收
，以及IIS空闲超时
设置是主要的可疑因素，但事实证明它们与此问题无关。严重的原因是什么？
在使用线程时。睡眠（3000）在同步测试中是可以的，当假装长时间运行的异步调用时，您将使用Task.Delay
获得更好的表示
public async Task<string> SlowMethod() {
    await Task.Delay(3000);
    return "data";
}

public异步任务SlowMethod（）{
等待任务。延迟（3000）；
返回“数据”；
}
罪犯
我终于打开引擎盖，试着检查每一个可能导致性能问题的细节。问题在于ThreadPool
。从现在起，把它称为问题似乎不再合适了
ThreadPool
的本质是不喜欢创建新线程并增加其池中的线程数，并且在任何情况下都有退回到最小线程数的趋势，这是这种现象的幕后原因
在我的环境中，ThreadPool
以4个线程开始。我通过打电话实现了这一点
ThreadPool.GetMinThreads(out int threadCount, out int portThread);

在初始阶段只有4个线程根本不足以在jMeter
测试期间处理大量传入的HTTP请求。因此，让ThreadPool
至少维护200个线程，这样就可以从200个线程开始解决这个问题
ThreadPool.SetMinThreads(200, 4);

现在，每个请求都将在测试结束前的3秒内得到处理。但不建议以无意义的方式操纵ThreadPool
中的最小线程数，因为这可能会影响应用程序的性能
这是来自
默认情况下，最小线程数设置为系统上的处理器数。您可以使用SetMinThreads方法增加最小线程数。但是，不必要地增加这些值可能会导致性能问题。如果同时启动的任务太多，则所有任务都可能看起来很慢。在大多数情况下，线程池使用其自己的线程分配算法将执行得更好。将最小值减少到少于处理器数量也会影响性能

不使用SetMinThreads的简单解决方案
使用任务延迟（3000）
；Sleep（3000）

也会清除这个问题。由于

Thread.Sleep（3000）

只是阻塞当前线程，因此它可能会导致

ThreadPool

创建更多线程。实际上，您可以在资源监视器中看到这种情况

这是任务延迟（3000）版本，我在测试开始1分钟后拍摄了这个屏幕截图。在测试过程中，仅创建了59个线程，并且数量保持不变或低于

这是
Thread.Sleep（3000）版本，我同时接受了这个。但是iisexpress已经产生了116个线程，并且在测试期间，的数量不断增加 ThreadPool.GetMinThreads(out int threadCount, out int portThread); ThreadPool.SetMinThreads(200, 4);