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Created April 5, 2012 12:32
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Python: how to create finalizer garbage
import gc
class A():
# For Python, finalizers means instance objects with __del__ methods.
def __del__(self):
pass
print gc.garbage
# []
# create a finalizer garbage: a
a = A() # refcnt: 1
a.reference_cycle = a # refcnt: 2
del a # refcnt: 1 (become garbage)
# garbage collection doesnt work on `a` because of finalizer,
# so gc moves `a` to garbage list
gc.collect()
print gc.garbage
# [<__main__.A instance at 0xb780560c>]
# Python programmers should take care not to create such things.
# The programmer has to deal with this if they insist on creating
# this type of structure.
del gc.garbage[:]
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