使用 Task.Factory.StartNew 时未触发 ExceptionFilterAttribute

Question

我正在开发一个 ASP.NET Web API，在我的一个控制器操作中我使用了一个 Task.Factory.StartNew 调用。

但是，当任务内部抛出异常时，这不会触发我配置的异常过滤器。

Controller.cs

public class MyController : ApiController
{
    [HttpPost]
    public HttpResponseMessage Post()
    {
        Task.Factory
            .StartNew(() => DoTheThing())
            .ContinueWith(tsk => { throw new Exception("Webhook Exception", tsk.Exception); }, TaskContinuationOptions.OnlyOnFaulted);

        return new HttpResponseMessage(HttpStatusCode.OK);
    }
}

ExceptionFilter.cs

public class ExceptionFilter : ExceptionFilterAttribute
{
    public override void OnException(HttpActionExecutedContext context)
    {
        throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError)
        {
            Content = new ObjectContent(typeof(object), new
            {
                Message = "Critical Error",
                ExceptionMessage = "An error occurred, please try again or contact the administrator.",
                Type = ExceptionType.Unhandled
            }, new JsonMediaTypeFormatter()),
            ReasonPhrase = "Critical Error"
        });
    }
}

Global.asax.cs

public class MyApplication : HttpApplication
{
    protected void Application_Start()
    {            
        GlobalConfiguration.Configuration.Filters.Add(new ExceptionFilter());
    }
}

我可以调试并触发 ContinueWith 方法并抛出新的异常。但是过滤器没有被触发。

Answer 1

过滤器没有被触发，因为异常是在与控制器动作方法线程不同的线程中抛出的。你可以：

1. 等待任务

   [HttpPost]
   public async Task<HttpResponseMessage> Post()
   {
       await Task.Factory
           .StartNew(() => DoTheThing())
           .ContinueWith(tsk => { throw new Exception("Webhook Exception", tsk.Exception); }, TaskContinuationOptions.OnlyOnFaulted);
   
       return new HttpResponseMessage(HttpStatusCode.OK);
   }
   

2. 等待任务

   [HttpPost]
   public HttpResponseMessage Post()
   {
       var task = Task.Factory
                      .StartNew(() => DoTheThing())
                      .ContinueWith(tsk => { throw new Exception("Webhook Exception", tsk.Exception); }, TaskContinuationOptions.OnlyOnFaulted);
   
       task.Wait();
   
       return new HttpResponseMessage(HttpStatusCode.OK);
   }
   

所有这些方法都在 action 方法中重新抛出异常，并且过滤器会捕获它。