>>> from multiprocessing import Pool
>>> import gc
>>> a = Pool(10)
>>> del a
>>> gc.collect()
0
>>>

After this, there are still left behind Process (Pool) or Dummy (ThreadPool) and big _cache data (If you did something with it) which lingers till the process dies.

You are correct on the other issue (I'm using and reading the Python 2 documentation which does not have that...).