title: Is there a way to check if a subprocess is still running?
body: <p>I'm launching a number of subprocesses with <code>subprocess.Popen</code> in Python.
  I'd like to check whether one such process has completed. I've found two ways of checking the status of a subprocess, but both seem to force the process to complete.
  One is using <code>process.communicate()</code> and printing the returncode, as explained here: <a href="https://stackoverflow.com/questions/14043030/checking-status-of-process-with-subprocess-popen-in-python">checking status of process with subprocess.Popen in Python</a>.
  Another is simply calling <code>process.wait()</code> and checking that it returns 0.</p>
  <p>Is there a way to check if a process is still running without waiting for it to complete if it is?</p>