I am not sure I understand it correctly or not. In python multiprocessing, it is using fork in Linux, so the children processes shares memory directly. The memory sharing will not change if you are not changing it since it uses copy-and-update rule. This memory sharing really can increase memory efficiency and also performance.
In Julia, it seems that the children processes are not using fork? As a result, we have to use @everywhere to execute the same code in all the processes?