title: Troubleshooting OSError: out of pty devices
body: <p>From time to time I'm getting an OSError exception with the message 'out of pty devices' when calling <code>pty.openpty()</code> (it's happening when a bunch of instances of my scripts run concurrently).</p>
  
  <p>What is the limit that I'm hitting?  How can I get around this?</p>
  
  <p>CentOS 5.6, Python 2.4</p>