0

i have a thread which produces multiple threads in it. how can i be sure if all the threads are completed? i have to call a method after all the threads are finished. this is not a duplicate like 

dim thread1.start()
dim thread2.start()
if (all threads are finished)
muFunc()
end if

you can see the sample code snippet below. see the code here

that is where i am stuck badly. what should i do? thanks in advance.

Khurram Zulfiqar
  • 5
  • 1
  • 5
  • 1
    Possible duplicate of [How to check if Thread finished execution](https://stackoverflow.com/questions/2773479/how-to-check-if-thread-finished-execution) – A Friend Jan 10 '18 at 13:53
  • 1
    In this example, it's probably easiest to just call `Join` on both threads. – dwilliss Jan 10 '18 at 14:12
  • 1
    Don't post pictures of code. – LarsTech Jan 10 '18 at 19:12
  • @larsTech. then why is the option given for the image upload? only for showing the result or DB changes ?? – Khurram Zulfiqar Jan 11 '18 at 08:06
  • If you look around at other questions, code is almost always in text form. This makes it easier for us to copy the code and test the problem. The option to upload images is for screen shots etc to help explain the problem better. – LarsTech Jan 11 '18 at 15:04

2 Answers2

0

Call this method from wherever you want (Form.Load, Button.Click...)
The Caller Event Handler/Method doesn't need to be an Async one

ThreadPoolManager()


Define a scope for the List(Of Thread) that holds the Thread Pool

Dim ThreadPool As List(Of Thread)


ThreadPoolManager() (a)waits StartThreads(), which starts all the Threads in the ThreadPool List. When the Async method returns, then calls MyFunctionWhenAllThreadsAreFinished()

  Private Async Sub ThreadPoolManager()

     If Await StartThreads() = True Then
        MsgBox("All Finished!", MsgBoxStyle.OkOnly, "Finally!")
        Call MyFunctionWhenAllThreadsAreFunished()
     Else
        MsgBox("Something went wrong!", MsgBoxStyle.OkOnly, "Damn it!")
     End If
  End Sub

The StartThreads() method initializes all the Threads in ThreadPool with the delegate worker method to invoke when the thread starts

  Protected Async Function StartThreads() As Task(Of Boolean)
     ThreadPool = New List(Of Thread)
     Dim MyThread1 As Thread = New Thread(AddressOf Me.MyThread1Work)
     Dim MyThread2 As Thread = New Thread(AddressOf Me.MyThread2Work)

     ThreadPool.AddRange({MyThread1, MyThread2})

     For Each _PT As Thread In ThreadPool : _PT.Start() : Next

     Return Await Task.Run(Function()
                             Dim AllFinished As Integer
                             While AllFinished < ThreadPool.Count
                                AllFinished = 0
                                For Each _T As Thread In ThreadPool
                                   If _T.IsAlive = False Then AllFinished += 1
                                Next
                             End While
                             Console.WriteLine("All Thread Finished")
                          Return True
                       End Function)
  End Function


  Private Sub MyThread1Work(_Obj As Object)
     Thread.Sleep(5000)
     Console.WriteLine("Thread 1 Finished")
  End Sub

  Private Sub MyThread2Work(_Obj As Object)
     Thread.Sleep(7000)
     Console.WriteLine("Thread 2 Finished")
  End Sub
Jimi
  • 29,621
  • 8
  • 43
  • 61
0

Use the Thread.IsAlive flag. This is to give the thread status.

(copied from the duplicate question)

(whew, I don't have the time to reverse engineer that previous answer to understand how it works.)

Doug Null
  • 7,989
  • 15
  • 69
  • 148