which packages do each of these 3 use?
subject to gil?
subject to gil? only 1 thread at a time. other thread like io mean gil go to another thread, so still faster. ie, only one thread running at a time, but if one thread is waiting for io response, can go to other thread.
(pool, process). in pool, each process has own gil. map, imap, imap unordered. used to get around gil by having multiple concurrent threads.