Parallel Library: does a delay on one degree of parallelism delay all of them?

collection.parallel.ForkJoinTasks.defaultForkJoinPool.setParallelism(parlevel: Int)

scala> import scala.collection.parallel._
import scala.collection.parallel._

scala> val pc = mutable.ParArray(1, 2, 3)
pc: scala.collection.parallel.mutable.ParArray[Int] = ParArray(1, 2, 3)

scala> pc.tasksupport = new ForkJoinTaskSupport(new scala.concurrent.forkjoin.ForkJoinPool(2))
pc.tasksupport: scala.collection.parallel.TaskSupport = scala.collection.parallel.ForkJoinTaskSupport@4a5d484a

scala> pc map { _ + 1 }
res0: scala.collection.parallel.mutable.ParArray[Int] = ParArray(2, 3, 4)

Environment.ProcessorCount

var block = new ActionBlock<Value>(
    value => GetWriteValueTask(value, priority)
    new ExecutionDataflowBlockOptions()
    {
        MaxDegreeOfParallelism = GetMaxNrParallelWrites();
    });

foreach (var value in values)
{
    block.Post(value);
}

public async Task TestTasksProperly()
{
    var urls = new List<string>();
    urls.AddRange(createUrls());

    var stopwatch = Stopwatch.StartNew();
    ConcurrentQueue<string> contents = new ConcurrentQueue<string>();
    await Task.WhenAll(urls.Select(url => QueryUrl(url, contents)))).ConfigureAwait(false);

    var time = stopwatch.ElapsedMilliseconds / 1000.0;
    Console.WriteLine("Time spent in Tasks : " + time);
    Console.WriteLine("Queue size : " + contents.Count);
}

private static async Task QueryUrl(string url, ConcurrentQueue<string> contents)
{
    using (var client = new HttpClient {Timeout = TimeSpan.FromSeconds(10)})
    {
        using (var response = await client.GetAsync(url).ConfigureAwait(false))
        {
            try
            {
                var content = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
                contents.Enqueue(content);
            }
            catch (Exception e)
            {
            }
        }
    }
}

$('.sub').stop(true)