using System;

using System.Threading;

using System.Threading.Tasks;

using System.Linq;

using System.Collections.Generic;

using System.Runtime.InteropServices;

using System.Diagnostics;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine($"FrameworkDescription: {RuntimeInformation.FrameworkDescription}");

        Console.WriteLine($"OSVersion: {Environment.OSVersion}");

        Console.WriteLine($"Environment.ProcessorCount: {Environment.ProcessorCount}");

        ThreadPool.SetMinThreads(workerThreads: 100, completionPortThreads: 10);

        HashSet<Thread> threads = new();

        int concurrency = 0;

        int maxConcurrency = 0;

        Parallel.ForEach(Enumerable.Range(1, 1500), n =>

        {

            lock (threads) maxConcurrency = Math.Max(maxConcurrency, ++concurrency);

            lock (threads) threads.Add(Thread.CurrentThread);

            // Simulate a CPU-bound operation that takes 200 msec

            Stopwatch stopwatch = Stopwatch.StartNew();

            while (stopwatch.ElapsedMilliseconds < 200) { }

            lock (threads) --concurrency;

        });

        Console.WriteLine($"Number of unique threads: {threads.Count}");

        Console.WriteLine($"Maximum concurrency: {maxConcurrency}");

    }

}