What should I keep in mind using Process.Start?

Question

What should I keep in mind using Process.Start?

Marc Menzel 121

Is there anything that I need to be aware of such as memory leaks? I know that I should use statements such as MyProcess.Close and MyProcess.Dispose. Is there anything else I need to be aware of?

4 answers

Your answer

Answer 1

Lex Li (Microsoft) 6,037 Microsoft Employee

How often in your project do you call Process.Start? Unless it spins out far too many processes and you forget to explicitly dispose the relevant objects you might experience some memory pressure. There isn't any memory leak though, as objects that properly implement IDisposable are ultimately cleaned up by the finalization process.

Marc Menzel 121 Reputation points

2021-12-11T05:32:47.057+00:00

I created a shell simulation application in my project. My project calls Process.Start everytime the user tells the program to open up a file or execute a program. When prcoesses exit, the program closes the process object created for the process and then disposes it.

Answer 2

Karen Payne MVP 35,586 Volunteer Moderator

Use a Using block to clean-up memory e.g.

Using process As Process = Process.Start("TODO")
    'Do whatever with the process
End Using

Which closes and disposes or do dispose in a try/finally statement.

A real world example

Public Shared Sub UnblockFiles(ByVal folderName As String)
    If Not Directory.Exists(folderName) Then
        Return
    End If

    Dim start = New ProcessStartInfo With {
        .FileName = "powershell.exe",
        .Arguments = $"Get-ChildItem -Path '{folderName}' -Recurse | Unblock-File",
        .CreateNoWindow = True
    }

    Using process As System.Diagnostics.Process = System.Diagnostics.Process.Start(start)

    End Using
End Sub

Rather than use WaitForExit use await WaitForExitAsync to keep your app responsive.

Marc Menzel 121 Reputation points

2021-12-11T03:23:04.51+00:00

What about this code block:`
If StartProcess = True Then
Dim startInfo As New ProcessStartInfo(Execution)
If ProcessPath <> "" Then startInfo.WorkingDirectory = ProcessPath
If CommandLineArguements <> "" Then ProcessArguments &= " " & CommandLineArguements
If ProcessArguments <> "" Then startInfo.Arguments = ProcessArguments
NumProcesses += 1
ExecutedProcesses(ProcessIndex) = Process.Start(startInfo)
ProcessIndex += 1
Executed = True
Else
Executed = False
End If

Marc Menzel 121

should I use something like:

   Private Sub CheckProcesses()
        While NumProcesses > 0 And Exiting = False
            Dim LoopCount As Integer = 0
            Dim LoopCount2 As Integer = 0
            CheckingProcesses = True
            For LoopCount = 0 To NumProcesses - 1
                Try
                    If ExecutedProcesses(LoopCount) IsNot Nothing Then
                        If ExecutedProcesses(LoopCount).HasExited = True Then

                            ExecutedProcesses(LoopCount).Close()
                            ExecutedProcesses(LoopCount).Dispose()
                            For LoopCount2 = LoopCount To NumProcesses - 1
                                ExecutedProcesses(LoopCount2) = ExecutedProcesses(LoopCount2 + 1)
                            Next
                            ProcessIndex -= 1
                            If ProcessIndex < 0 Then ProcessIndex = 0
                            NumProcesses -= 1
                            If NumProcesses < 0 Then NumProcesses = 0
                        End If
                    End If
                Catch ex As Exception
                    Exit For
                End Try
            Next LoopCount
            If NumProcesses <= 0 Then
                CheckingProcesses = False
                Exit While
            Else
                Threading.Thread.Sleep(CheckProcessesRestingTime)
            End If
        End While

    End Sub

Marc Menzel 121 Reputation points

2021-12-11T03:29:17.713+00:00
to check for exited process and then clean them up. It's referenced by:

Private Sub StartProcessCheck() Dim P As New Threading.Thread(AddressOf CheckProcesses) P.Start() End Sub
Marc Menzel 121 Reputation points

2021-12-11T03:32:05.577+00:00

I also am using this code:
Private Sub CloseProcesses()
Dim LCV As Integer = 0
Try
For LCV = 0 To NumProcesses - 1
ExecutedProcesses(LCV).Close()
ExecutedProcesses(LCV).Dispose()
Next
Catch ex As Exception
LCV = 0
End Try
NumProcesses = 0
End Sub

Answer 3

Marc Menzel 121

What do you think about how I should approach this?

Marc Menzel 121 Reputation points

2021-12-11T09:43:58.55+00:00

I am simulating a command shell which calls the Process.Start() method each time the user wants to open a file or execute another application or program. I close each process object after the process exits and then I dispose the process object.

Answer 4

Hi @Marc Menzel ,

My project calls Process.Start everytime the user tells the program to open up a file or execute a program. When prcoesses exit, the program closes the process object created for the process and then disposes it.

It is recommended to use the using block to automatically call the dispose method of the process object at the end of the code segment.
Best Regards.
Jiachen Li

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What should I keep in mind using Process.Start?

4 answers

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