如何测量 C# 中并行任务或多线程程序的总执行时间？

Question

I am a novice in C#/.NET. Here I am trying to run the following parallel tasks and measure the total execution time.

But after running the code the execution time is showing just > 6 ms which is way less than it is supposed to be. I am not sure if there is any misplacing of the Stopwatch() function that's giving this unexpected result.

Your help will be appreciated :

namespace Tests
{
    class Prod
    {
        static void Main(string[] args)
        {
            Stopwatch s = new Stopwatch();
            s.Start();
            {
                Task T1 = Task.Run(() =>
                {
                    for (int i = 0; i <= 5000; i++)
                        Console.WriteLine("Test1:" + i);
                });
                Task T2 = Task.Run(() =>
                {
                    for (int i = 0; i <= 5000; i++)
                        Console.WriteLine("Test2:" + i);
                });
                Task T3 = Task.Run(() =>
                {
                    for (int i = 0; i <= 5000; i++)
                        Console.WriteLine("Test3:" + i);
                });

            }
            s.Stop();
            Console.WriteLine("Press any key to quit");
            Console.ReadKey();


            Console.WriteLine("Total Task Ellapsed time -> {0}", s.ElapsedMilliseconds);
        }

    }

}

Answer 1

You need a Task.WaitAll before the stop of the Stopwatch ( s.Stop() in your code)

for example:

Task.WaitAll(T1,T2,T3);
s.Stop();

Answer 2

One solution would be to wait for all Tasks to be completed using Task.WaitAll

Task.WaitAll(T1,T2,T3);

Complete Code

    Stopwatch s = new Stopwatch();
    s.Start();
    {
            Task T1 = Task.Run(() =>
            {
                for (int i = 0; i <= 5000; i++)
                    Console.WriteLine("Test1:" + i);
            });
            Task T2 = Task.Run(() =>
            {
                for (int i = 0; i <= 5000; i++)
                    Console.WriteLine("Test2:" + i);
            });
            Task T3 = Task.Run(() =>
            {
                for (int i = 0; i <= 5000; i++)
                    Console.WriteLine("Test3:" + i);
            });

            Task.WaitAll(T1,T2,T3); // Change here
   }
   s.Stop();
   Console.WriteLine("Press any key to quit");
   Console.WriteLine("Total Task Ellapsed time -> {0}", s.ElapsedMilliseconds);