Demo for https://github.com/gfoidl/Stochastics/issues/9

Static_Partitioner.cs

using System;
using System.Collections;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    static class Program
    {
        static void Main()
        {
            var ranges  = new ConcurrentDictionary<int, List<(int Start, int End)>>();
            const int N = 10_000;

            Parallel.ForEach(
                new MyPartitioner(N),
                range =>
                {
                    AddRange(range);

                    for (int i = range.Start; i < range.End; ++i)
                        for (int j = 0; j < 1_000 * (N - range.Item2); ++j)
                            ;
                }
            );

            foreach (var item in ranges.OrderBy(i => i.Key))
            {
                Console.WriteLine($"Thread-ID: {item.Key}");

                foreach (var range in item.Value.OrderBy(r => r.Start))
                    Console.WriteLine($"\t{range,-15}\t{range.End - range.Start}");
            }
            //-----------------------------------------------------------------
            void AddRange((int Start, int End) range)
            {
                var list = new List<(int Start, int End)> { range };
                ranges.AddOrUpdate(
                    Thread.CurrentThread.ManagedThreadId,
                    list,
                    (id, l) =>
                    {
                        l.Add(range);
                        return l;
                    }
                );
            }
        }
    }
}

Code for MyPartitioner is in https://gist.github.com/gfoidl/d8250ff11a5c70972cb8164622792ba1