Ok, I will try that. I noticed that the memory usage doesnt go up instantly, (although it does go up very quickly). Basically, it doesn’t go up fast enough to indicate that its copying over the entire dictionary to each worker. Makes me wonder if its only copying over the first level’s appropriate key, i.e. if my overall dictionary has 20 keys, and the appropriate data for a particular example lies in key 14, then only the values coresponding to key 14 will be copied over- does this sound right?