BackgroundWorker Still Blocks IHttpHandler

Question

所以我有UI在我的应用程序中创建日历事件。当创建新事件时，我为我的所有用户（约3,000）创建通知。我新这将需要一段时间，因为我需要写入数据库为每个用户创建他们的通知，所以我创建了一个继承自BackgroundWorker的类。我并不在意是否创建了通知（我这样做，但不是在为最终用户完成请求的情况下），所以我认为这将是一种有效的方法。

然而当我去执行它时，即使在调用context.Response.End()之后，HttpHandler还是等待后台工作完成。我调试线程和HttpHandler和BackgroundWorker有不同的线程ID。我不确定我是否以某种方式阻止HttpHandler返回，或者我误解了BackgroundWorker类的用途。

class EventHandler : IHttpHandler 
{ 
    ... 
    public void ProcessRequest(HttpContext context) 
    { 
     ... 
     // I need this to finish before the response ends 
     CalendarEvent event = CreateCalendarEvent(); 
     List<int> users = GetUsersFromDB(); 
     if(event != null) // The event was created successfully so create the notifications 
     { 
      // This may take a while and does not effect the UI on 
      // client side, so it can run in the background 
      NotificationBackgroundWorker notificationWorker = new NotificationBackgroundWorker(notification, users); 
      notificationWorker.RunWorkerAsync(); 
     } else { 
      ... 
      // Log Error and set status code for response 
      ... 
     } 
     ... 
     context.Response.End() 
    } 
    ... 
} 

class NotificationBackgroundWorker : BackgroundWorker 
{ 
    private Notification notification; 
    private List<int> users; 

    public NotificationBackgroundWorker(Notification newNotification, List<int> usersToNotify) : base() 
    { 
     this.notification = newNotification; 
     this.users = usersToNotify; 
     this.DoWork += DoNotificationWork; 
    } 

    private void DoNotificationWork(object sender, DoWorkEventArgs args) 
    { 
     CreateUserNotifications(notification, users); 
    } 

    private void CreateUserNotifications(Notification notification, List<int> userList) 
    { 
     // This is where the bottleneck is occurring because there 
     // is one DB write per user 
     foreach (int userId in userList) 
     { 
      ... 
      // Create the notification for each user 
      ... 
     } 
    } 
} 

任何洞察力都会很棒。预先感谢一堆！

Answer 1

BackgroundWorker与当前SynchronizationContext整合。它的设计方式是，在BackgroundWorker完成之前，它不会让当前请求结束。这是你大部分时间想要的。

我建议你通过开始新的Task将工作项排入线程池。