Actually, the issue is that Python does not redirect output until the script is complete. I believe IronPython will redirect while the script is running (have not tested this though), but unfortunately, regular Python must wait for the script to end before redirecting output.
Windows Form - Running python script, redirected output delayed
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02-07-2022 - |
Question
I'm running a windows form with a background worker to update a textbox based on the output of a python script. Its all working pretty well, except the redirected output is not in real time; its delayed pretty significantly.
Any ideas how I can increase the redirected outputs response time?
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Diagnostics;
using System.Threading;
using System.IO;
namespace JiraHeartBeat
{
public partial class Form1 : Form
{
delegate void AppendTextDelegate(string text);
BackgroundWorker Worker = new BackgroundWorker();
public Form1()
{
InitializeComponent();
Worker.DoWork += new DoWorkEventHandler(Worker_DoWork);
Worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(Worker_RunWorkerCompleted);
}
void Worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
StartButton.PerformClick();
}
private void StartButton_Click(object sender, EventArgs e)
{
if (!Worker.IsBusy)
{
Worker.RunWorkerAsync();
}
}
public void Worker_DoWork(object sender, DoWorkEventArgs e)
{
Process pro = new Process();
pro.StartInfo.RedirectStandardOutput = true;
pro.StartInfo.RedirectStandardError = true;
pro.StartInfo.UseShellExecute = false;
pro.StartInfo.CreateNoWindow = true;
pro.EnableRaisingEvents = true;
pro.OutputDataReceived += new DataReceivedEventHandler(OnDataReceived);
pro.ErrorDataReceived += new DataReceivedEventHandler(OnDataReceived);
pro.StartInfo.FileName = "C:\\Python27\\python.exe";
pro.StartInfo.Arguments = "\"C:\\Python27\\myscript.py\"";
try
{
pro.Start();
pro.BeginOutputReadLine();
pro.BeginErrorReadLine();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
Thread.Sleep(5000 * 60);
}
public void OnDataReceived(object sender, DataReceivedEventArgs e)
{
if (e.Data != null)
{
string temp = (e.Data) + Environment.NewLine;
appendText(temp);
}
}
public void appendText(string text)
{
if (ResultTextBox.InvokeRequired)
{
ResultTextBox.Invoke(new AppendTextDelegate(appendText), new object[] { text });
}
else
{
ResultTextBox.AppendText(text);
}
}
}
}
Solution
OTHER TIPS
Try removing the below line from the Worker_DoWork
, I suspect it is delaying the execution of the RunWorkerCompleted
event.
Thread.Sleep(5000 * 60);
EDIT
Since the above approach was attempted and did not solve the problem entirely I investigated a bit further and confirmed that when capturing the output from a python script the response is delayed. However, by adding a call to sys.stdout.flush()
I was able to get the desired behavior. Here is the python script I used which worked successfully in my test.
import time
import sys
for x in xrange(0,11):
print x
time.sleep(1)
sys.stdout.flush()