title: Execute multiple .py files at the same time
body: <p>I have three .py files that I want to run at the same time in a Python script file. I initially called <code>subprocess.call()</code> three times (once for each .py file) but remembered that it blocks until the command is finished. I tried <code>subprocess.Popen(['screen', 'python_file'])</code> since I believe it doesn't block but when I was checking for the processes with <code>screen -ls</code> there was only one process running. How do I get all three programs running at the same time with a Python script? Should I be using the <code>multiprocessing</code> or <code>multithreading</code> library?</p>
  
  <p>Edit: The other processes aren't supposed to finish since they're running in an infinite loop. Here's exactly what I had in my Python script file. I'm using <code>screen</code> because each .py file has stdout logged onto the terminal and I want to be able to see what is being logged for each one.</p>
  
  <p><br><code>subprocess.Popen(['screen', './submitter.py'])</code>
  <br><code>subprocess.Popen(['screen', './worker.py'])</code>
  <br><code>subprocess.Popen(['screen', './tester.py'])</code></p>