線程池完成工作，當程序關閉時

Question

當程序關閉時，有什麼方法讓ThreadPool完成它的工作？

當我使用一個正常的線程，我只是在t.Join放在FormClosing事件..但ThreadPool似乎沒有任何聯接方法？

Answer 1

我想我可能已經解決了吧..

Imports System.Threading 

Module Module1 

    Sub Main() 
     Dim t As New Tool 
     t.WaitToJoin() 
     Console.WriteLine("Done") 
     t.WaitToJoin() 
     Console.WriteLine("Done") 
     t.WaitToJoin() 
     Console.WriteLine("Done") 
     t.WaitToJoin() 
     Console.WriteLine("Done") 
     t.Update() 
     t.WaitToJoin() 
     Console.WriteLine("Done") 

     t.Update() 
     Thread.Sleep(1500) 
     t.Update() 
     t.WaitToJoin() 
     Console.WriteLine("Done") 

     t.Update() 
     Thread.Sleep(1500) 
     t.Update() 
     Thread.Sleep(1500) 
     t.Update() 
     Thread.Sleep(5500) 
     t.Update() 
     Thread.Sleep(10000) 
     t.Update() 
     t.WaitToJoin() 
     Console.WriteLine("Done") 
    End Sub 

End Module 

Public Class Tool 
    'Thread Stuff 
    Private threads As Integer = 0 
    Private threadsdone As AutoResetEvent = New AutoResetEvent(False) 

    Public Sub WaitToJoin() 
     If Interlocked.Read(threads) > 0 Then 
      threadsdone.WaitOne(New TimeSpan(0, 0, 30)) ' just to be sure not to lock forever, by some wierd reason, a timeout on 30 sec is added 
     End If 
    End Sub 

    Public Sub Update() 
     Threading.ThreadPool.QueueUserWorkItem(New Threading.WaitCallback(AddressOf HardWork), "Doing dome hard work...") 
    End Sub 

    Public Sub HardWork(ByVal state As Object) 
     Dim num As Integer = Interlocked.Increment(threads) 
     Console.WriteLine(num & " - " & state) 

     Thread.Sleep(10000) 
     If Interlocked.Decrement(threads) = 0 Then 
      threadsdone.Set() 
     End If 
    End Sub 
End Class 

Answer 2

我不認爲你可以讓一個線程池等待。如何使用Task而不是線程池？下面的代碼有效。您可以查看完整的示例here爲了更好地理解

Dim taskA = Task.Factory.StartNew(Sub() DoSomeWork(10000000)) 
    taskA.Wait() 
    Console.WriteLine("taskA has completed.")