#14058: Weakly reference binary operation codomains
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Reporter: robertwb | Owner: rlm
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.7
Component: memleak | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Robert Bradshaw | Merged in:
Dependencies: #12313 | Stopgaps:
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Comment (by SimonKing):
Before posting a reply to Nils' post, here is an example that the
existence of A and B does not ensure the survival of the pushout of A and
B. First, attach [attachment:testcoerction.py] into a Sage session. Then:
{{{
sage: %attach /home/simon/SAGE/work/memleak/testcoercion.py
sage: OA = A()
sage: OB = B()
sage: cm = sage.structure.element.get_coercion_model()
sage: OC = cm.explain(OA,OB)
Coercion on left operand via
Conversion map:
From: A
To: C
Coercion on right operand via
Conversion map:
From: B
To: C
Arithmetic performed after coercions.
Result lives in C
sage: OC.is_coercion_cached(OA)
True
sage: OC.is_coercion_cached(OB)
True
sage: del OC
sage: import gc
sage: _ = gc.collect()
sage: len([X for X in gc.get_objects() if isinstance(X,C)])
0
sage: xc = OA(1)*OB(1)
sage: isinstance(xc.parent(),C)
True
sage: del xc
sage: _ = gc.collect()
sage: len([X for X in gc.get_objects() if isinstance(X,C)])
0
}}}
I do believe that this is ''not'' desired behaviour.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14058#comment:15>
Sage <http://www.sagemath.org>
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