我运行了几个任务并将它们保存在列表中以检查它们是否已经完成。
我发现来自async
方法的任务始终显示为RanToCompletion
,尽管任务本身仍在运行。
在这两种情况下,有没有办法从Task
对象获取“完整”信息?
这是一个显示此行为的简单测试用例。我使用/不使用async
方法运行两个任务,并检查完成期间和之后的状态。
private void test()
{
;
Action actionAsync = funcAsync;
Task taskAsync = Task.Run(actionAsync);
Action action = func;
Task task = Task.Run(action);
var statusAsync = taskAsync.Status;
var status = task.Status;
// stati are either WaitingToRun or Running
Thread.Sleep(TimeSpan.FromSeconds(2));
// Now it's quite certain, that both have started
var statusAsync2 = taskAsync.Status;
var status2 = task.Status;
Debug.Assert(statusAsync2 == TaskStatus.RanToCompletion);
Debug.Assert(status2 == TaskStatus.Running);
;
Thread.Sleep(TimeSpan.FromSeconds(12));
// Now it's quite certain, that both have finished
var statusAsync3 = taskAsync.Status;
var status3 = task.Status;
;
Debug.Assert(statusAsync3 == TaskStatus.RanToCompletion);
Debug.Assert(status3 == TaskStatus.RanToCompletion);
}
private async void funcAsync()
{
await Task.Delay(TimeSpan.FromSeconds(10));
}
private void func()
{
Thread.Sleep(TimeSpan.FromSeconds(10));
}
答案 0 :(得分:8)
我发现来自异步方法的任务总是显示为RanToCompletion,尽管任务本身仍在运行。
是的,因为您的void
方法已经完成,并且Task.Run
正在调用所有方法。相反,如果您使用:
private async Task FuncAsync()
{
await Task.Delay(TimeSpan.FromSeconds(10));
}
然后使用Func<Task>
代替Action
,然后您就会致电Task.Run(Func<Task>)
,一切都会好起来。
简短而完整的例子:
using System;
using System.Threading;
using System.Threading.Tasks;
class Test
{
static void Main()
{
Func<Task> func = FuncAsync;
Task task = Task.Run(func);
for (int i = 0; i < 7; i++)
{
Console.WriteLine(task.Status);
Thread.Sleep(1000);
}
}
private static async Task FuncAsync()
{
await Task.Delay(TimeSpan.FromSeconds(5));
}
}
输出:
WaitingForActivation
WaitingForActivation
WaitingForActivation
WaitingForActivation
WaitingForActivation
RanToCompletion
RanToCompletion
尽可能避免编写void
异步方法。它们基本上只应用于事件处理程序。