c# - ContinueWhenAll 操作中的 Task.Wait

Question

我正在致力于将线程合并到我的 azure 代码中，以便将事物放入队列中。为此，我使用了 http://www.microsoft.com/download/en/details.aspx?id=19222作为引用。

我的将多条消息排入队列的代码如下所示:

public void AddMessagesAsync(IEnumerable<IQueueMessage> messages, string queue = null, TimeSpan? timeToLive = null)
{
  //check if we need to switch queues
  if (!String.IsNullOrEmpty(queue))
  {
    SetCurrent(queue);
  }

  //setup list of messages to enqueue
  var tasks = new List<Task>();
  Parallel.ForEach(messages, current => {
    if (timeToLive.HasValue)
    {
      //create task with TPL
      var task = Task.Factory.FromAsync(Current.BeginAddMessage, Current.EndAddMessage, Convert(current), timeToLive.Value, tasks); 
      //setup continuation to trigger eventhandler
      tasks.Add(task.ContinueWith((t) => AddMessageCompleted(t)));
    }
    else
    {
      //create task with TPL
      var task = Task.Factory.FromAsync(Current.BeginAddMessage, Current.EndAddMessage, Convert(current), tasks);
      //setup continuation to trigger eventhandler
      tasks.Add(task.ContinueWith((t) => AddMessageCompleted(t)));
    }
  });

  //setup handler to trigger when all messages are enqueued, a we are blocking the thread over there to wait for all the threads to complete
  Task.Factory.ContinueWhenAll(tasks.ToArray(), (t) => AddMessagesCompleted(t));               
}

private void AddMessagesCompleted(Task[] tasks)
{
  try
  {
    //wait for all tasks to complete
    Task.WaitAll(tasks);
  }
  catch (AggregateException e)
  {
    //log the exception
    var ex = e;
    //return ex;
  }

  if (AddedMessages != null)
  {
    AddedMessages(tasks, EventArgs.Empty);
  }
}

现在我的问题是关于延续中的Task.Wait(这是根据MS提供的文档)。等待您已经知道已经完成的线程似乎有点奇怪，对吧？我能想象的唯一原因是冒泡错误并处理这些错误。我在这里遗漏了什么吗？

Answer 1

Task.WaitAll()会抛出 AggregateException当至少一个任务实例被取消时 - 或者 - 在至少一个任务实例执行期间抛出异常。

ContinueWhenAll()不会抛出此异常，它只是在一切完成取消或未完成等时启动您的最后一个任务。