.NET Framework Task.WhenAny
示例
var random = new Random();
IEnumerable<Task<int>> tasks = Enumerable.Range(1, 5).Select(n => Task.Run(async() =>
{
Console.WriteLine("I'm task " + n);
await Task.Delay(random.Next(10,1000));
return n;
}));
Task<Task<int>> whenAnyTask = Task.WhenAny(tasks);
Task<int> completedTask = await whenAnyTask;
Console.WriteLine("The winner is: task " + await completedTask);
await Task.WhenAll(tasks);
Console.WriteLine("所有任务都完成了！");