Python: module for creating PID-based lockfile?

Question

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)

Answer 1

If you can use GPLv2, Mercurial has a module for that:

http://bitbucket.org/mirror/mercurial/src/tip/mercurial/lock.py

Example usage:

from mercurial import error, lock

try:
    l = lock.lock("/path/to/lock", timeout=600) # wait at most 10 minutes
    # do something
except error.LockHeld:
     # couldn't take the lock
else:
    l.release()