关于AysncController的一次测试（url重写后静态页文件内容的读取是否需要使用异步？）

2023-03-13 15:10:07

因为做网站的静态页缓存，所以做了这个测试

MVC项目

准备了4个Action,分两组，一组是读取本地磁盘的一个html页面文件，一组是延时2秒

public class TestController : Controller

{

    public ActionResult Article(string name)

    {

        string path = @"I:\c#\nn.html";

        using (StreamReader reader = new StreamReader(path))

        {

            return Content(reader.ReadToEnd());

        }

    }

    public async Task<ActionResult> Article2(string name)

    {

        string path = @"I:\c#\nn.html";

        using (StreamReader reader = new StreamReader(path))

        {

            return Content(await reader.ReadToEndAsync());

        }

    }

    public ActionResult Index1()

    {

        Thread.Sleep(2000);

        return Content("synchronized");

    }

    public async Task<ActionResult> Index2()

    {

        await Task.Delay(2000);

        return Content("asynchronized");

    }

}

控制台程序，测试代码

class Program

{

    static void Main(string[] args)

    {

        var syncUrl = "http://localhost:61771/Test/Article";

        var asyncUrl = "http://localhost:61771/Test/Article2";

        var syncUrl2 = "http://localhost:61771/Test/Index1";

        var asyncUrl2 = "http://localhost:61771/Test/Index2";

        var count = 20;

        int i = 0;

        while (true)

        {

            Console.WriteLine();

            Benchmark(asyncUrl, count);

            Benchmark(syncUrl, count);

            Benchmark(asyncUrl2, count);

            Benchmark(syncUrl2, count);

            i++;

            if (Console.ReadKey().Key == ConsoleKey.C)

            {

                break;

            }

        }

        Console.ReadKey();

    }

    static void Benchmark(string url, int count)

    {

        var stopwatch = new Stopwatch();

        stopwatch.Start();

        var threads = new List<Thread>();

        var countdown = new CountdownEvent(count);

        for (int i = 0; i < count; i++)

        {

            threads.Add(new Thread(() =>

            {

                using (var client = new WebClient())

                {

                    client.DownloadData(url);

                    countdown.Signal();

                }

            }));

        }

        for (int i = 0; i < count; i++)

        {

            threads[i].Start();

        }

        while (!countdown.IsSet) ;

        stopwatch.Stop();

        Console.WriteLine(string.Format("{0} costs {1} ms", url, stopwatch.ElapsedMilliseconds.ToString()));

    }

}

测试结果

运行环境：笔记本电脑本地测试。

执行结果：

count = 20
count = 100
count = 200

count = 500

测试时WebClient抛出了请求超时的警告，

代码调整如下：

 public class NewWebClient : WebClient

 {

 	private int _timeout;

 	public NewWebClient()

 	{

 		this._timeout = 60000;

 	}

 	public NewWebClient(int timeout)

 	{

 		this._timeout = timeout;

 	}

 	protected override WebRequest GetWebRequest(Uri address)

 	{

 		var result = base.GetWebRequest(address);

 		result.Timeout = this._timeout;

 		return result;

 	}

 }

 static void Benchmark(string url, int count)

 {

 	var stopwatch = new Stopwatch();

 	stopwatch.Start();

 	var threads = new List<Thread>();

 	var countdown = new CountdownEvent(count);

 	for (int i = 0; i < count; i++)

 	{

 		threads.Add(new Thread(() =>

 		{

 			using (var client = new NewWebClient(30 * 60 * 1000))

 			{

 				client.DownloadData(url);

 				countdown.Signal();

 			}

 		}));

 	}

 	for (int i = 0; i < count; i++)

 	{

 		threads[i].Start();

 	}

 	while (!countdown.IsSet) ;

 	stopwatch.Stop();

 	Console.WriteLine(string.Format("{0} costs {1} ms", url, stopwatch.ElapsedMilliseconds.ToString()));

 }

count = 1000
count = 1500

总结

按照过去看过的资料描述，应该是 AsyncController虽然会因为线程切换而使单个请求增加额外的处理时间，但使耗时的操作不再占用工作线程，从而可以让IIS在相同时间内可以响应更多的请求，提高吞吐率。

第二组Action(延时2秒)的测试结果数据确实反映了这一效果。

但第一组读取本地文件的测试结果则是单个请求的处理时间，异步Action明显高于同步不说，处理相同请求数所消耗的时间也是异步高于同步……，磁盘文件的并发读取是不是有什么限制呢？，待确认。

UrlRewrite

在已经完成MapHandler后就不能重写了，所以一般在BeginRequest的时候，执行重写
IIS的url不区分大小写
///////home//////index//////////////////,request.Url.PathAndQuery依然是/home/index/
/index.html/ 末尾带斜杠访问一个动态页可以正常访问（样式可能会乱掉），但访问一个静态页会报404

补充测试

    protected void Application_BeginRequest()

    {

        var context = HttpContext.Current;

        var request = context.Request;

        if (request.RequestType == "GET")//过滤所有API

        {

            string regularUrl = request.Url.PathAndQuery;

            if (regularUrl.StartsWith("/Test/Article3"))

            {

                context.RewritePath("/Project_Readme.html");

            }

            else if (regularUrl.StartsWith("/Test/Article4"))

            {

                string path = context.Server.MapPath("~/Project_Readme.html");

                if (File.Exists(path))

                {

                    using (StreamReader reader = new StreamReader(path))

                    {

                        context.Response.Write( reader.ReadToEnd());

                        context.Response.End();

                    }

                }

            }

        }

    }