#14711: Memleak when creating QuadraticField
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Reporter: jpflori | Owner:
Type: defect | davidloeffler
Priority: critical | Status: new
Component: number fields | Milestone: sage-5.12
Keywords: memleak, number field, | Resolution:
QuadraticField | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: u/SimonKing/ticket/14711 | Commit:
Dependencies: | Stopgaps:
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Comment (by jpflori):
Replying to [comment:27 SimonKing]:
> Replying to [comment:25 jpflori]:
> > Not sure about the other uses of morphism though, a morphism could
then survive when its parent dies.
>
> Isn't the homset containing the morphism keeping a strong reference to
domain and codomain, too? Or did I change this somewhere? So, would having
a weak reference to the domain actually help?
Don't know, we'll have to check.
>
> > But whats the point of keeping a morphism alive if you don't use its
parent?
>
> Well, imagine a method that returns a morphism. You have constructed the
domain and the codomain inside of the method. It would be awkward to
return `domain, codomain, morphism` instead of only one item, `morphism`.
But if the morphism only keeps a weak reference to the domain, and if you
only return the morphism, then the domain might be garbage collected
during return, and this would make the morphism useless.
Yeah I got that if you don't store an outside refernce to the domain, then
it will get gc'ed.
But I don't really see what kind of method would return just such a
morphism, internally constructing the domain without you providing it (or
having other references ot it somehow), do you have actual examples in
mind?
Anyway, another solution would be to add an option to Action/Morphism and
so on to only use weakref optionally.
--
Ticket URL: <http://trac.sagemath.org/ticket/14711#comment:29>
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