Question

我的测试表明，在代码队列中排列10个theads并同时运行其中的3个。没关系。但我无法从课堂上获得回报价值。

在终止程序之前，Finalize事件永远不会触发。它奇怪，因为我希望线程结束，它会自动摧毁自己。但事实并非如此。

我看到我需要使用委托函数来实现这一点，但是我无法使用委托使用此队列示例。

任何人都可以帮助我获得回调函数内的返回值吗？我疯了，显然我的知识还不够。

Imports System.ComponentModel
Imports System.Threading
Public Class Form1
    Private tasks As New Queue(Of Action)
    Private RunningThread As Integer
    Private Lock As New Object
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnButton1.Click
        Dim i As Integer
        For i = 1 To 10
            Dim w As New Work()
            w.Data = i
            Dim Task As New Action(AddressOf w.DoWork)
            If RunningThread < 3 Then
                Task.BeginInvoke(AddressOf Callback, Nothing)
                Threading.Interlocked.Increment(RunningThread)
                Console.WriteLine(i.ToString & " basladi")
            Else
                Console.WriteLine(i.ToString & " bekliyor")
                SyncLock (Lock)
                    tasks.Enqueue(Task)
                End SyncLock
            End If
        Next
    End Sub
    Private Sub Callback(ByVal o As Object)
        If tasks.Count > 0 Then
            Dim Task As Action
            SyncLock (Lock)
                Task = tasks.Dequeue
            End SyncLock
            Task.BeginInvoke(AddressOf Callback, Nothing)
        Else
            Threading.Interlocked.Decrement(RunningThread)
        End If
    End Sub
End Class

这是我打电话的非常简单的课程。

Public Class Work
    Public Data As Integer
    Public Function DoWork() As String
        Console.WriteLine(Data.ToString & " inside class")
        Thread.Sleep(1000)
        Return Data.ToString & " output parameter"
    End Function
    Protected Overrides Sub Finalize()
        Console.WriteLine(Data.ToString & " this code never runs until form close.")
        MyBase.Finalize()
    End Sub
End Class

注意：这是目前正在运行的代码。

Answer 1

Work.Finalize在终止之前不会运行，因为在完成后不会破坏局部变量w。在重新分配变量期间，由垃圾收集器管理Finalize。你想用它做什么？也许您应该使用其他解决方案。
Button1_Click中的代码无法捕获Work.DoWork的回复。我使用Tasks.Task（Of String）代替Action，将它们全部放入1个列表进行处理。

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
    Dim i As Integer
    For i = 1 To 10
        Dim w As New Work()
        w.Data = i
        Dim t = Tasks.Task(Of String).Factory.StartNew(AddressOf w.DoWork)
        RunningTasks.Add(t)
    Next

    i = 0
    For Each t In RunningTasks
        i = i + 1
        Console.WriteLine(String.Format("Task {0} completed with value: {1}", i, t.Result))
    Next
End Sub

输出：

1 inside class
3 inside class
4 inside class
2 inside class
5 inside class
7 inside class
8 inside class
6 inside class
9 inside class
Task 1 completed with value: 1 output parameter
10 inside class
Task 2 completed with value: 2 output parameter
Task 3 completed with value: 3 output parameter
Task 4 completed with value: 4 output parameter
Task 5 completed with value: 5 output parameter
Task 6 completed with value: 6 output parameter
Task 7 completed with value: 7 output parameter
Task 8 completed with value: 8 output parameter
Task 9 completed with value: 9 output parameter
Task 10 completed with value: 10 output parameter

您还可以使用Action（Of String）并将BeginInvoke更改为： task.BeginInvoke(outputVariable, AddressOf Callback, Nothing)

由于我不确定你想要对输出做什么，所以我不知道如何在回调中处理它。

需要从具有此编码样式的线程获取返回值

1 个答案: