Question

Is there a way in the new async dotnet 4.5 library to set a timeout on the Task.WhenAll method? I want to fetch several sources, and stop after say 5 seconds, and skip the sources that weren’t finished.

Answer 1

You could combine the resulting Task with a Task.Delay() using Task.WhenAny():

await Task.WhenAny(Task.WhenAll(tasks), Task.Delay(timeout));

If you want to harvest completed tasks in case of a timeout:

var completedResults =
  tasks
  .Where(t => t.Status == TaskStatus.RanToCompletion)
  .Select(t => t.Result)
  .ToList();