Multiple-reader-one-writer (MROW) locking -- soliciting improvements

[Matthew Scott]

After being introduced to the concept of MROW locking, I sought a
general implementation of it in Python that implemented reentrant
locks, had a simple interface, and was unit tested.

I found some implementations, but none had all three of these
qualities, so I wrote this recipe:

http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/413393

I'm posting a link to it here in case others find it useful, and also
to solicit feedback for improving the recipe.

Enjoy!

- Matthew