Does python garbage-collect at the end of an iteration in a loop? -

please observe simple code:

    import random     while true:         l = list( str(random.random())) 

question: if let run, python run out of memory?
reason asking:
first iteration of loop, list created, , 'l' assigned represent list. next iteration of loop, list created, 'l' yanked previous list , and assigned new list. previous list has lost reference. previous list going garbage collected? if not @ end of each iteration, hope?

having said that, expand scenario bit further multiprocessing:

    import random     while true:         l1 = list( str(random.random()))                     pseudo: multiprocessing.queue.put(l1)         # how l1 handled here?         # l1 .copy()-ed queue or referenced queue?         # l1 destoryed in process (this while loop) @ end of iteration? 

the primary means of garbage collection reference counting in cpython (the reference implementation of language). when there no longer references object, memory occupies freed , can reused other python objects. (it may or may not ever released operating system.) there few exceptions of objects never freed: smallish integers, interned strings (including literals), empty tuple, none.

so answer initial question, l going reassigned new list on each iteration. @ point, previous list has no references , memory released immediately.

with regard second example, putting multiprocessing queue is, of necessity, copy operation. object must serialized ("pickled" in python parlance) sent new process, has own memory space , can't see original process's memory. when, in loop, reassign li next list, previous list has no references and, again, released.

at end of loop, l or l1 variable still refers list: 1 created in last iteration of loop. if want release object, del l or del l1 respectively.

ps -- when objects contain references (either directly, or indirectly through chain of other objects), referred cyclic reference. these aren't collected automatically reference counting , python has separate garbage collector runs periodically clean them up.