Dennis Sweeney <[email protected]> added the comment:
The save-a-boolean-for-each-context-manager approach has an issue if used with
concurrent generators, where the lifetimes of two generator objects might be
overlapping but not completely nested, as shown below. The same issue should
arise when using multiple threads. The approach in no_gc.py with counting the
times_disabled does not run into the same issue.
>>> from contextlib import contextmanager
>>> import gc
>>> @contextmanager
def no_gc():
was_enabled = gc.isenabled()
try:
yield
finally:
if was_enabled:
gc.enable()
>>> def gen1():
with no_gc():
yield "a"
yield "b"
yield "c"
>>> def gen2():
with no_gc():
yield 1
yield 2
yield 3
>>>
>>> g1 = gen1()
>>> g2 = gen2()
>>> next(g1)
'a'
>>> next(g2)
1
>>> list(g1)
['b', 'c']
>>> gc.isenabled() # should be False!
True
>>> list(g2)
[2, 3]
----------
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Python tracker <[email protected]>
<https://bugs.python.org/issue41545>
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