[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.
If this call is protected by the same lock as any other collection, then splitting them won't make the call thread safe. Using concurrent map is not enough to make this safe