异步任务比同步任务快多少

using System.Diagnostics;

namespace TestStatue
{
    internal class Program
    {
        static async Task Main(string[] args)
        {
            DateTime now = DateTime.Now;
            var t1 = new List<Task<HttpResponseMessage>>();
            for (int i = 0; i < 100; i++)
            {
                var resultResponse = new HttpClient().SendAsync(new HttpRequestMessage { RequestUri = new Uri("https://www.baidu.com") });
                t1.Add(resultResponse);

                // var result = await resultResponse.Content.ReadAsStreamAsync();
            }
            var t2 = new List<Task<Stream>>();

            t1.ForEach(async x =>
            {
                var res = await x;
                t2.Add(res.Content.ReadAsStreamAsync());
            });


            Task.WaitAll(t2.ToArray());
            Console.WriteLine($"运行时间：{DateTime.Now.Subtract(now).TotalMilliseconds}");
        }
    }
}

//using System.Diagnostics;

//namespace TestStatue
//{
//    internal class Program
//    {
//        static async Task Main(string[] args)
//        {
//            Stopwatch stopwatch = new Stopwatch();
//            stopwatch.Start();
//            var t2 = new List<Task<Stream>>();
//            for (int i = 0; i < 100; i++)
//            {
//                var resultResponse = await new HttpClient().SendAsync(new HttpRequestMessage { RequestUri = new Uri("https://www.baidu.com") });

//                var result = resultResponse.Content.ReadAsStreamAsync();
//                t2.Add(result);
//            }

//            Task.WaitAll(t2.ToArray());

//            //Console.WriteLine(result);
//            stopwatch.Stop();
//            Console.WriteLine($"运行时间：{stopwatch.ElapsedMilliseconds}");
//        }
//    }
//}



//using System.Diagnostics;

//namespace TestStatue
//{
//    internal class Program
//    {
//        static async Task Main(string[] args)
//        {
//            Stopwatch stopwatch = new Stopwatch();
//            stopwatch.Start();
//            for (int i = 0; i < 100; i++)
//            {
//                var resultResponse = await new HttpClient().SendAsync(new HttpRequestMessage { RequestUri = new Uri("https://www.baidu.com") });

//                var result = await resultResponse.Content.ReadAsStreamAsync();
//            }

//            //Console.WriteLine(result);
//            stopwatch.Stop();
//            Console.WriteLine($"运行时间：{stopwatch.ElapsedMilliseconds}");
//        }
//    }
//}



//using System.Diagnostics;

//namespace TestStatue
//{
//    internal class Program
//    {
//        static void Main(string[] args)
//        {
//            Stopwatch stopwatch = new Stopwatch();
//            stopwatch.Start();
//            Parallel.For(0, 10, (i) =>
//             {
//                 var resultResponse = new HttpClient().Send(new HttpRequestMessage { RequestUri = new Uri("https://www.baidu.com") });

//                 var result = resultResponse.Content.ReadAsStream();
//             });

//            //Console.WriteLine(result);
//            stopwatch.Stop();
//            Console.WriteLine($"运行时间：{stopwatch.ElapsedMilliseconds}");
//        }
//    }
//}


//using System.Diagnostics;

//namespace TestStatue
//{
//    internal class Program
//    {
//        static void Main(string[] args)
//        {
//            Stopwatch stopwatch = new Stopwatch();
//            stopwatch.Start();
//            for (int i = 0; i < 100; i++)
//            {
//                var resultResponse = new HttpClient().Send(new HttpRequestMessage { RequestUri = new Uri("https://www.baidu.com") });

//                var result = resultResponse.Content.ReadAsStream();
//            }

//            //Console.WriteLine(result);
//            stopwatch.Stop();
//            Console.WriteLine($"运行时间：{stopwatch.ElapsedMilliseconds}");
//        }
//    }
//}

异步任务一直用，突然想测试下异步任务比同步任务快多少。就写了个下载的方法。因为获取string只有异步，所以过去stream，比较的时候无逻辑代码差异。

例子代码从下往上看，发现异步个同步执行时间是差不多的。

后面就加了并行，当然并行的话拿来比较没意义了。

后面就加入task.waitall，发现改善效果很明显。内部机智没深究！

这里单个例子用了两个等待，所以用起来又有点别扭。出现了第一个demo和第二个demo。

这里的执行时间有又差别！知识储备有限，稍微总结一下:

现有循环业务下第一个demo比最的两个快了六七倍，比第二个demo快了两三倍！

标签：异步,同步,Console,var,任务,resultResponse,stopwatch,new,result
来源： https://www.cnblogs.com/morec/p/16098209.html