How not to freeze in VB.NET while Process.WaitForExit()?

Question

What I have:

Dim test As Process = Process.Start("powershell.exe", "-executionpolicy
remotesigned -file C:\temp\test.ps1")

test.WaitForExit()

Finally while wait for "test" to exit, my GUI freezes. How to make it smooth?

Why have you posted a snippet of [another question](http://stackoverflow.com/questions/38144171/how-to-loop-smooth-and-correctly-in-vb-net) as a brand new question within a short time of each other? — gravity, Jul 01 '16 at 13:37
This really has nothing to do with the PowerShell tag either... — Austin T French, Jul 01 '16 at 14:44

score 4 · Accepted Answer · answered Jul 01 '16 at 13:58

4

You could use a BackgroundWorker to run this code on a separate thread, currently you are running it on the UI thread which causes it to freeze.

This should get you started:

Private Sub startWorker()
    Dim powershellWorker As New BackgroundWorker
    AddHandler powershellWorker.DoWork, AddressOf doWork

    powershellWorker.RunWorkerAsync()
End Sub

Private Sub doWork(ByVal sender As Object, ByVal e As DoWorkEventArgs)
    Dim test As Process = Process.Start("powershell.exe", "-executionpolicy remotesigned -file C:\temp\test.ps1")
    test.WaitForExit()
End Sub

answered Jul 01 '16 at 13:58

Nathan

227
3
15

Good idea anyway :) The problem now is that I wanna change an textbox.text in the background worker. It gives me " Invalid thread -border operation" as an error (translated with google). Can u help me there too? Thx alot btw for u help ;) – hannir Jul 06 '16 at 17:44
Sure, ask a new question and me or someone else will try to help you there. – Nathan Jul 07 '16 at 08:24

honzajscz · Answer 2 · 2016-07-01T17:35:32.567

1

The test.WaitForExit() is a blocking method and it will block your UI thread. Try running the code in a parallel task and await it

 Dim task As Task = Task.Run(Sub()
     Dim test As Process = Process.Start("powershell.exe", "-executionpolicy remotesigned -file C:\temp\test.ps1")
     Process.WaitForExit()
     Return test
  End Sub)
 Dim test2 As Process = Await task
 // some code that will execute after the process completes

You might need to add the async key word to outer method declaration.

Please note that I am a C# person :-)

edited Jul 01 '16 at 17:35

answered Jul 01 '16 at 13:21

honzajscz

2,850
1
27
29

2

You never call `Process.WaitForExit()`. This will only wait for the code being executed (which is done in no-time). Create a task instead in which you only run `Process.WaitForExit()`. – Visual Vincent Jul 01 '16 at 13:29
I have forgotten to add that line there. Now it is better. Thx – honzajscz Jul 01 '16 at 17:36

How not to freeze in VB.NET while Process.WaitForExit()?

2 Answers2