[TACHYON-220] WIP Comments describing issues and possible solutions 

Some initial comments to help improve the performance of master info. From what I gather there is locking on stack local objects that are never really put back into the map. I would appreciate suggestions before implementing it, hence the WIP tag.
This is needed because the map is not thread safe. Changing the map could make this safe; would have to look closer to verify though that it would no longer be needed