IronLanguages / IronLanguages/ironpython3

generator does not free resources after iteration

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Dominant language
C#
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Description

For example:

import gc
import weakref

class qwerty:
    def __iter__(self):
        yield

a = qwerty()
r = weakref.ref(a)
i = iter(a)
a = list(i) # consumes the generator and clears the reference
gc.collect() # probably required for IronPython
assert r() is None

Causes a failure in test_userlist (test_free_after_iterating) from CPython 3.5.

Contributor guide

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running test_userlist, specifically test_free_after_iterating, and reproduce the weakref example from the issue. Trace the generator's lifetime after list(i) consumes it and compare the result with CPython 3.5; done means the weak reference is cleared and the test passes, including after gc.collect().

Written by the indexing model from the issue text.

Assessment

Tech stack
csharp, python
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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