How do I force a single instance of a python app?

[Darren New]

Grant Edwards wrote:
>  2) PIDs roll over, so there's a remote chance that the process
>     that created the lock file crashed without deleting it, and
>     weeks and weeks later some other unlreated process is
>     running with that same PID. 

Or 4.5 minutes later, depending on how busy your system is.

>  1) I don't know if file creation is an atomic operation on
>     non-Unix systems.

Or on UNIX systems under load, for that matter.  (Yes, Virginia, UNIX has
bugs too. Can you tell I've been bitten? :-)
 
-- 
Darren New / Senior MTS & Free Radical / Invisible Worlds Inc.
San Diego, CA, USA (PST).  Cryptokeys on demand.
The tragedy of the commons applies to monitizing eyeballs, too.