Program.cs

using System;
using System.Linq;
using System.Collections.Generic;
using System.Collections;
using System.Threading;
using System.Threading.Tasks;
using log4net;
using log4net.Config;

class Program
{
    private static ILog s_logger = LogManager.GetLogger("Program");

    static void Main(string[] args)
    {
        BasicConfigurator.Configure();

        var task1 = DoSomeWork("chunk 1");
        var task2 = DoSomeWork("chunk 2");
        var task3 = DoSomeWork("chunk 3");

        Task.WaitAll(task1, task2, task3);
    }

    static async Task DoSomeWork(string chunkName)
    {
        using (new SomeDisposable(chunkName))
        //using (NDC.Push(chunkName))
        using (log4net.GlobalContext.Stacks["NDC"].Push(chunkName))
        //using (log4net.LogicalThreadContext.Stacks["NDC"].Push(chunkName))
        //using (log4net.ThreadContext.Stacks["NDC"].Push(chunkName))
        {
            s_logger.Info("Starting to do work");
            await Task.Delay(5000);
            s_logger.Info("Finishing work");
        }
    }
}

public class SomeDisposable : IDisposable
{
    private static ILog s_logger = LogManager.GetLogger("SomeDisposable");
    private string m_chunkName;
    public SomeDisposable(string chunkName)
    {
        m_chunkName = chunkName;
        s_logger.InfoFormat("Created disposable for chunk {0} on thread {1}!", m_chunkName, Thread.CurrentThread.ManagedThreadId);
    }

    void IDisposable.Dispose()
    {
        s_logger.InfoFormat("Disposed disposable for chunk {0} on thread {1}!", m_chunkName, Thread.CurrentThread.ManagedThreadId);
    }
}