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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