using System;

using System.Threading.Tasks;

using System.Collections.Concurrent;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

​

public class Program

{

    //this is me typing right hnow...

    //and now i will run it

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Tester tester = new Tester();

        tester.Main2();

​

    }

}

public class Tester

{

    ConcurrentStack<int> values = new ConcurrentStack<int>();

    public void Main2 ()

    {

        // TASK.RUN

        int number = 5;

        RunAsTasks(number);

​

​

        // PARALLEL

        int threadsPerProcessor = 1;

        int maxParallelism = (Environment.ProcessorCount * threadsPerProcessor) /2;

        RunAsParallel(number, maxParallelism);

    }

    void RunAsTasks(int number)

{

    values.Clear();

    Stopwatch sw = new Stopwatch();

    sw.Start();

    var calcs = GetCalcTasks(number).ToArray();

    Task.WaitAll(calcs);

    int total = values.Sum();

    Console.WriteLine("Total = " + total);

    Console.WriteLine("Elapsed, Tasks = " + sw.Elapsed);

}

void RunAsParallel(int number, int maxParallelism = -1)

{

    values.Clear();

    Stopwatch sw = new Stopwatch();

    sw.Start();

    var calcs = GetCalcs(number).ToArray();

    ParallelOptions options = new ParallelOptions() {

        MaxDegreeOfParallelism = maxParallelism

    };

    Parallel.ForEach(calcs, options, c => {

        DoCalc(c);

    });

    int total = values.Sum();

    Console.WriteLine("Total = " + total);

    Console.WriteLine("Elapsed, Parallel = " + sw.Elapsed);

}

​

List<Calc> GetCalcs(int number) {

    List<Calc> result = new List<Calc>(number);

    for(var i=0; i<number; i++)

    {

        result.Add(new Calc());

    }

    return result;

}

List<Task> GetCalcTasks(int number) {

    List<Task> tasks = new List<Task>(number);

​

    var calcs = GetCalcs(number);

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

    {

        var calc = calcs[i];

        tasks.Add(Task.Run(() =>

        {

            DoCalc(calc);

        }));

    }

    return tasks;

}

​

void DoCalc(Calc calc) {

    int next = calc.Do();

    values.Push(next);

    //Debug.WriteLine(calc.Index + " = " + next);

}

​

​

​

public class Calc 

{

    private static int _Index = default;

    int _Result;

    public int Index {get; private set;}

    public Calc()

    {

        Index = _Index++;

        Random r = new Random(_Index);

        _Result = r.Next(1, 12000);

    }

    public int Do() {

        Slow(TimeSpan.FromSeconds(1));

        return _Result; 

    }

​

    public void Slow(TimeSpan span)

    {

        var end = DateTime.Now + span;

        while (DateTime.Now < end)

            /*nothing here */

            ;

    }

}

}