#13394: Write a WeakValueDictionary with safer key removal
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Reporter: nbruin | Owner: rlm
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.13
Component: memleak | Resolution:
Keywords: | Merged in:
Authors: Simon King | Reviewers:
Report Upstream: None of the above | Work issues:
- read trac for reasoning. | Commit:
Branch: | c3dba989f73c1eec0a66cf72ae203132fe33b5da
u/SimonKing/ticket/13394 | Stopgaps:
Dependencies: |
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Comment (by nbruin):
Replying to [comment:18 SimonKing]:
> Why is a weak self-reference needed? Is this just to prevent problems
that could arise when one of the internally used weak references creeps
out of the dict?
See [http://bugs.python.org/issue417795]. I'm not convinced by its
reasoning. Certainly in sage we're already depending on cyclic GC left and
right, so I don't see the issue (we wouldn't dream of subclassing
WeakValueDictionary with a `__del__` method). It's also a very old fix,
probably stemming from a time that people were still suspicious about the
cyclic GC. If this stuff would get merged in Python, it would probably
need the weakref, but I don't think it needs it in Sage.
For iterator stuff: in Python3 this is fixed. See
[http://hg.python.org/cpython/file/default/Lib/weakref.py] for starters
(and [http://hg.python.org/cpython/file/default/Lib/_weakrefset.py] for
`_IteratorGuard`). You probably just want to backport that stuff wholesale
into your own module.
--
Ticket URL: <http://trac.sagemath.org/ticket/13394#comment:19>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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