Read Standard Output and check status of multiple processes VB.NET - vb.net

Question

I run multiple command line processes, starting them in a loop. It works and starts all of them async.
Public Sub DoWork
Dim i As Integer = 0
While (Args_reader.Peek() > -1)
i = i + 1
MyArg = Args_reader.ReadLine
Dim MyArg As String
Dim MyProcess(i) As Process
MyProcess(i) = New Process
With MyProcess(i).StartInfo
.FileName = MyFile
.Arguments = MyArg
.UseShellExecute = False
.CreateNoWindow = True
.RedirectStandardInput = True
.RedirectStandardOutput = True
.RedirectStandardError = True
.WindowStyle = ProcessWindowStyle.Hidden
End With
MyProcess(i).Start()
End While
Args_reader.Close()
i = 0
End Sub
Haw can I read stdOutput for all of them and check their status?
I need to wait until they finish to continue executing the program.

Answer 1

I would recommend you to assign async events to every process inside a loop, so they get fired when that process has any output. Standard Output or Error Output:
Dim Proceso As New Process
'Add the event handlers:
AddHandler Proceso.OutputDataReceived, AddressOf CallbackProcesoAsync
AddHandler Proceso.ErrorDataReceived, AddressOf ErrorDataReceivedAsync
Dim startInfo As New ProcessStartInfo
startInfo.FileName = execFile
startInfo.RedirectStandardOutput = True
startInfo.RedirectStandardError = True
startInfo.CreateNoWindow = False
Proceso.StartInfo = startInfo
Proceso.Start()
the async events should be something like this:
Private Sub CallbackProcesoAsync(sender As Object, args As System.Diagnostics.DataReceivedEventArgs)
If Not args.Data Is Nothing AndAlso Not String.IsNullOrEmpty(args.Data) Then
'args.Data have the output
End If
End Sub
Private Sub ErrorDataReceivedAsync(sender As Object, args As System.Diagnostics.DataReceivedEventArgs)
If Not args.Data Is Nothing AndAlso Not String.IsNullOrEmpty(args.Data) Then
'args.Data have the output
End If
End Sub