Huerfanitos!

test_pool.py

import time
import threading
from multiprocessing.pool import ThreadPool

def wait():
    time.sleep(5)

class A(object):
    def __init__(self):
        self.p = ThreadPool(10)

a = A()
a.p.apply_async(wait)

#a.p.close()
#a.p.join()

del a

print threading.enumerate()