Source code for the article "Tudo ao mesmo tempo agora com C#" originally published at https://medium.com/pricefy-labs

parallel_parent_and_children.cs

private static void ParallelParentAndChildren()
{
    var numberOfIterations = 1000;

    var min = 0;
    var max = 100_000_000;

    Console.WriteLine($"Generating random numbers from {min} to {max} over {numberOfIterations} iterations");

    var nums = GenerateRandomNumbers(numberOfIterations, min, max).Select(num => (long)num).ToArray();

    var task = Task.Factory.StartNew(
        () => ProcessNumbers(nums),  // <-- let's pretend it is a so freaking CPU-intensive method
        CancellationToken.None,
        TaskCreationOptions.None,
        TaskScheduler.Default
    );

    Console.WriteLine("Spawned parallel process of numbers and will wait until completion");

    task.Wait();

    Console.WriteLine("Parallel process of numbers has completed");
}

private static void ProcessNumbers(long[] nums)
{
    var odds = new ConcurrentBag<long>();
    var evens = new ConcurrentBag<long>();

    Console.WriteLine("Will divide odds / evens in parallel");

    Parallel.ForEach(nums, (num) =>
    {
        if (num % 2 != 0)
            odds.Add(num);
        else
            evens.Add(num);
    });

    Task.Factory.StartNew(
        () => ExpensiveWorkWithOdds(odds.ToArray()),
        CancellationToken.None,
        TaskCreationOptions.AttachedToParent,  // <-- pay attention at here
        TaskScheduler.Default
    );

    Console.WriteLine("Spawned parallel expensive work on odds");

    Task.Factory.StartNew(
        () => ExpensiveWorkWithEvens(evens.ToArray()),
        CancellationToken.None,
        TaskCreationOptions.AttachedToParent,  // <-- pay attention at here
        TaskScheduler.Default
    );

    Console.WriteLine("Spawned parallel expensive work on evens");
}