c# – 多线程为什么简单的多任务不起作用？

var finalList = new List<string>();
var list = new List<int> {1,2,3,4,5,6,7,8,9,10 ................. 999999};

var init = 0;
var limitPerThread = 5;

var countDownEvent = new CountdownEvent(list.Count);

for (var i = 0; i < list.Count; i++)
{
    var listToFilter = list.Skip(init).Take(limitPerThread).ToList();
    new Thread(delegate()
                   {
                       Foo(listToFilter);
                       countDownEvent.Signal();
                   }).Start();    
    init += limitPerThread;
}

//wait all to finish
countDownEvent.Wait();


private static void Foo(List<int> listToFilter)
{
    var listDone = Boo(listToFilter);
    lock (Object)
    {
        finalList.AddRange(listDone);
    }
}

这不是：

var taskList = new List<Task>();

for (var i = 0; i < list.Count; i++)
{
    var listToFilter = list.Skip(init).Take(limitPerThread).ToList();
    var task = Task.Factory.StartNew(() => Foo(listToFilter)); 
    taskList.add(task);   
    init += limitPerThread;
}

//wait all to finish
Task.WaitAll(taskList.ToArray());

此过程最终必须至少创建700个线程.当我使用Thread运行时,它可以工作并创建所有这些.但是使用Task它不会..它似乎没有启动倍数任务异步.

我真的想知道为什么……任何想法？

编辑

PLINQ的另一个版本(如建议的那样).

var taskList = new List<Task>(list.Count);
Parallel.ForEach(taskList,t =>
                   {
                       var listToFilter = list.Skip(init).Take(limitPerThread).ToList();
                       Foo(listToFilter);
                       init += limitPerThread;
                       t.Start();
                   });
Task.WaitAll(taskList.ToArray());

EDIT2：

public static List<Communication> Foo(List<Dispositive> listToPing)
{
    var listResult = new List<Communication>();
    foreach (var item in listToPing)
    {
        var listIps = item.listIps;
        var communication = new Communication
        {
            IdDispositive = item.Id
        };

        try
        {
            for (var i = 0; i < listIps.Count(); i++)
            {
                var oPing = new Ping().Send(listIps.ElementAt(i).IpAddress,10000);
                if (oPing != null)
                {
                    if (oPing.Status.Equals(IPStatus.TimedOut) && listIps.Count() > i+1)
                        continue;
                    if (oPing.Status.Equals(IPStatus.TimedOut))
                    {
                        communication.Result = "NOK"; 
                        break;
                    }
                    communication.Result = oPing.Status.Equals(IPStatus.Success) ? "OK" : "NOK";
                    break;
                }
                if (listIps.Count() > i+1)
                    continue;
                communication.Result = "NOK";
                break;
            }
        }
        catch
        {
            communication.Result = "NOK";
        }
        finally
        {
            listResult.Add(communication);
        }
    }

    return listResult;
}