I am proposing an extension to the multiprocessing.Pool API that allows for an alternative way to pass data to Pool worker processes, *without* using globals. A PR has been opened https://github.com/python/cpython/pull/9627, extensive test coverage is also included, with all tests & CI passing on github. Please see this blog post https://thelaziestprogrammer.com/python/multiprocessing-pool-expect-initret-... for details, motivation, and use cases of the API extension before reading on. In *short*, the implementation of the feature works as follows: 1. Exposes a kwarg on Pool.__init__ called `expect_initret`, that defaults to False. When set to True: 1. Capture the return value of the initializer kwarg of Pool 2. Pass this value to the function being applied, as a kwarg. Again, in *short,* the motivation of the feature is to provide an explicit "flow of data" from parent process to worker process, and to avoid being *forced* to using the *global* keyword in initializer, or being *forced* to create global variables in the parent process. The interface is 100% backwards compatible through Python3.x (and perhaps beyond).