title: Python: module for creating PID-based lockfile?
body: <p>I'm writing a Python script that may or may not (depending on a bunch of things) run for a long time, and I'd like to make sure that multiple instances (started via cron) don't step on each others toes. The logical way to do this seems to be a PID-based lockfile… But I don't want to re-invent the wheel if there is already code to do this.</p>
  
  <p>So, is there a Python module out there which will manage the details of a PID-based lockfile?</p>