Replacing ROD with regular dictionary

If others could test this in the context of using W with multiprocessing and let me know if this fixes the original problem of not being able to use W with mp, that would be great. See #314 for more details on the issue.

If this fixes the issue, then this can be merged and closed.

If it does not fix the issue, let's keep this open and document the issue further here as we work towards an ultimate solution.