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

问题

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.

回答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

来源：https://stackoverflow.com/questions/19514098/read-standard-output-and-check-status-of-multiple-processes-vb-net

标签

vb.net

asynchronous

process

stdout