帮助Task并行库使用(Help with Task parallel library usage)

 我正在尝试使用任务并行库为一系列项目调度函数调用。 
 
 以下不起作用 
 
List<Task> tasks = new List<Task>();

foreach(var someValue in aCollection)
{
   var t = Task.Factory.StartNew(() => DoSomeWork(someValue));
   tasks.Add(t);
}

Task.WaitAll(tasks.ToArray());
 
 但下面的工作 
 
Task.WaitAll(aCollection.Select(a => Task.Factory.StartNew(() => DoSomeWork(a))).ToArray());
 
 对于第一种方法，它执行一次然后停止。 我不确定它是否会覆盖引用或其他内容。 有人可以。 说明？ 
 
 还有一种方法可以将一些序列号传递给Task，可用于识别首先安排的任务。 我的意思是我想等待所有任务完成，然后根据集合中的顺序排序结果。 

I am trying to schedule a function call for a sequence of items using Task parallel library.
 
The following does not work
 
List<Task> tasks = new List<Task>();

foreach(var someValue in aCollection)
{
   var t = Task.Factory.StartNew(() => DoSomeWork(someValue));
   tasks.Add(t);
}

Task.WaitAll(tasks.ToArray());
 
But the below works
 
Task.WaitAll(aCollection.Select(a => Task.Factory.StartNew(() => DoSomeWork(a))).ToArray());
 
For the first approach it executes once and then stops. I am not sure if its overwriting the reference or something. Can someone pls. explain?
 
Also is there a way to pass some sequence number to Task that can be used to identifiy which task was scheduled first. I mean I want to wait for all the tasks to complete but then order the results based on the sequence in the collection.

原文：https://stackoverflow.com/questions/4927989