import gc
import multiprocessing
 
class Cycle(object):
def __init__(self):
self.g = self.gen()
next(self.g)
def gen(self):
try:
yield self
finally:
print('Doing one-time cleanup')
 
def work():
# Pretend this does work that triggers a collection cycle
gc.collect()
 
# Get some allocations done now that would have triggered an
# inconvenient collection if we did them later
p = multiprocessing.Process(target=work)
p.start()
p.join()
 
print('Creating cyclic trash')
Cycle()
 
try:
p = multiprocessing.Process(target=work)
p.start()
p.join()
 
work()
 
print('Oops, did cleanup twice')
finally:
print('Doing other one-time cleanup')
 
print("*Didn't* do the other cleanup twice, even though we forked to run p")

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