Question

我想停止正在运行的线程并立即启动一个新线程而无需等待。我的线程从数据库中读取并在UI中显示（计算后）结果。如果用户单击按钮我需要＆＃34;重启＆＃34;与其他参数的线程。所以我必须停止正在运行的线程（不等待）并重新启动它。这是一个简单的例子：

Dim mythread As Threading.Thread = Nothing
Dim mythreadCancel As Boolean = False
Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
    Try
        If Not mythread Is Nothing Then
            If mythread.IsAlive Then
                mythreadCancel = True
            End If
        End If
        mythread = New Threading.Thread(AddressOf threadRunning)
        mythreadCancel = False 'if i set this here, the other thread is not stopping!
        mythread.Start()
    Catch ex As Exception
        MsgBox(ex.Message)
    End Try
End Sub

Private Sub threadRunning()
    Try
        While True
            'long operation on Database
            Threading.Thread.Sleep(10000)
            If mythreadCancel = True Then
                Exit Sub
            End If
            'ui operation (if not canceled)
            '....
        End While
    Catch ex As Exception
        MsgBox(ex.Message)
    End Try
End Sub

Private Sub BtnStop_Click(sender As Object, e As EventArgs) Handles BtnStop.Click
    mythreadCancel = True
End Sub

如果我设置了取消线程的标志，我需要将其设置回来，如果我启动下一个线程。我怎样才能给正在运行的线程一个标志来中止？

我也使用过thread.abort。工作正常，但现在我已经读过，我永远不应该这样做。

[编辑]

感谢您的评论。我现在发现使用令牌。我需要与STA的线程。它也适用于任务。但STA更复杂。

Dim tokenSource As New CancellationTokenSource()
Private Sub Button5_Click(sender As Object, e As EventArgs) Handles Button5.Click
    Try
        tokenSource.Cancel()
        tokenSource = New CancellationTokenSource()
        Dim mythread As New Threading.Thread(AddressOf ThreadRunning)
        mythread.SetApartmentState(ApartmentState.STA)
        mythread.Start(tokenSource.Token)
     Catch ex As Exception
        MsgBox(ex.Message)
    End Try
End Sub

Private Sub ThreadRunning(ByVal obj As Object)
    Try
        Dim token As CancellationToken = CType(obj, CancellationToken)
        Debug.WriteLine("Task starting")
        While True
            'long operation on Database
            Threading.Thread.Sleep(1000)
            If token.IsCancellationRequested Then
                Debug.WriteLine("Exit Task")
                Exit Sub
            Else
                Debug.WriteLine("Task running")
            End If
            'ui operation (if not canceled)
            '....
        End While
    Catch ex As Exception
        MsgBox(ex.Message)
    End Try
End Sub

这似乎工作正常。这是正确的方法吗？

[/编辑]

vb.net在没有等待的情况下停止长时间运行的线程并启动一个新线程

0 个答案: