How to determine when all task is completed

Question

here is sample code for starting multiple task

Task.Factory.StartNew(() =>
        {
            //foreach (KeyValuePair<string, string> entry in dicList)

            Parallel.ForEach(dicList,
                entry =>
                {

                    //create and add the Progress in UI thread
                    var ucProgress = (Progress)fpPanel.Invoke(createProgress, entry);

                    //execute ucProgress.Process(); in non-UI thread in parallel. 
                    //the .Process(); must update UI by using *Invoke
                    ucProgress.Process();

                    System.Threading.Thread.SpinWait(5000000);
                });
        });
.ContinueWith(task => 
  {
      //to handle exceptions use task.Exception member

      var progressBar = (ProgressBar)task.AsyncState;
      if (!task.IsCancelled)
      {
          //hide progress bar here and reset pb.Value = 0
      }
  }, 
  TaskScheduler.FromCurrentSynchronizationContext() //update UI from UI thread
  );

when we start multiple task using Task.Factory.StartNew() then we can use .ContinueWith() block to determine when each task finish. i mean ContinueWith block fire once for each task completion. so i just want to know is there any mechanism in TPL library. if i start 10 task using Task.Factory.StartNew() so how do i notify after when 10 task will be finish. please give some insight with sample code.

Answer 1

if i start 10 task using Task.Factory.StartNew() so how do i notify after when 10 task will be finish

Three options:

• The blocking Task.WaitAll call, which only returns when all the given tasks have completed
• The async Task.WhenAll call, which returns a task which completes when all the given tasks have completed. (Introduced in .NET 4.5.)
• TaskFactory.ContinueWhenAll, which adds a continuation task which will run when all the given tasks have completed.