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CSharp · Console

/Program.cs

using System;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using System.Diagnostics;

class Program
{
    static void Main(string[] args)
    {
        TaskScheduler scheduler = new ConcurrentExclusiveSchedulerPair(
            TaskScheduler.Default, maxConcurrencyLevel: 3).ConcurrentScheduler;

        TaskFactory taskFactory = new TaskFactory(scheduler);

        Stopwatch stopwatch = Stopwatch.StartNew();

        Task[] tasks = Enumerable.Range(1, 12).Select(i => taskFactory.StartNew(async () =>
        {
            Thread.Sleep(500); // This counts towards the maxConcurrencyLevel
            Console.WriteLine($"Task: {i}, Elapsed: {stopwatch.Elapsed}");
            await Task.Delay(500); // This doesn't count towards the maxConcurrencyLevel
        }).Unwrap()).ToArray();
        Task.WaitAll(tasks);
    }
}