中止异步操作 [英] Abort the asynchronous operation

问题描述

有人可以告诉我如何终止异步操作吗?

这样的问题.

我创建了从不同数据库收集一些信息的应用程序.而且此过程可能非常持久，因此我将收集过程称为异步过程，它有可能随时中断.

我所做的:

Hi,
Can anybody tell me how to abort the asynchronous operation?

Problem such.

I have created the application which gathers some information from different databases. And this process can be very durable, therefore I call procedure of collection asynchronous that there was a possibility it to interrupt at any time.

That I have made:

Public class Manager

    Public Sub ImportTransfers
        'Collect information
    End Sub

End class

Public Class frm_Main

    Delegate Sub dlg_Importer()
    Dim Importer As dlg_Importer
    Dim CallBackImport As AsyncCallback

    Private Sub frm_Main_Load
          Call Init_Delegates()
    End Sub

        Private Sub Init_Delegates()
          Importer = AddressOf Manager.ImportTransfers
          CallBackImport = AddressOf CallBack_Import
        End Sub

        Private Sub btn_ImportTransfers_Click
          Importer.BeginInvoke(CallBackImport, Nothing)
    End Sub

        Sub CallBack_Import(ByVal ar As IAsyncResult)
          Importer.EndInvoke(ar)
        End Sub

        Private Sub btn_StopProcess_Click
           'I do not know what to write here to stop process...
        End Sub

End Class

CallBack_Import过程在ImportTransfers过程结束后完成，但是如何通过按钮btn_StopProcess单击来停止ImportTransfers?

The CallBack_Import procedure is fulfilled after ImportTransfers procedure end, but how to stop ImportTransfers by button btn_StopProcess Click?

推荐答案

Makso，我认为异步调用不会解决你的问题.您唯一的解决方案是将该异步线程的引用发送回主线程，这是非常肮脏的解决方案.

我的意思是设置表单级别变量

Makso, I don''t think that asynchronous call will solve your problem. The only solution you have is to send a reference of that asynchronous thread back to the main thread, a very very dirty solution.

What I mean is setting up a form level variable

System.Threading.Thread asynchOperation;

然后在您的异步方法中像这样设置它.

And in your asynchronous method just set it like this.

this.asynchOperation = System.Threading.Thread.CurrentThread;

然后在您的btn_StopProcess_Click()

And then in your btn_StopProcess_Click()

this.asynchOperation.Abort();

另外，不要忘记将异步操作包装在try catch和catching System.Threading.ThreadAbortException.
中
但我会严格建议不要使用此解决方案.中止 ThreadPool 线程不是一个主意，任何人都会喜欢.据报道，它还是可以重新创建的.作为一个实验，我本人放弃了大约70个线程，每次我返回带有ManagedID 6的线程.我尚未确认非托管状态，但至少它正在重新创建这些线程.

更好的解决方案是显式使用 Thread 类

Also don''t forget to wrap your asynchronous operation in try catch and catching System.Threading.ThreadAbortException.

But i will strictly advise against this solution. Aborting a ThreadPool thread is not an idea, anyone will favor. It''s reported to be recreated anyway. I myself has aborted as an experiment about 70 threads and everytime i got back a thread with managedID 6. I haven''t confirmed the unmanaged status, but at least it was recreating these threads.

A better solution would be using Thread class Explicitly

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