#11521: Memleak when resolving the action of Integers on an Elliptic Curve
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Reporter: jpflori | Owner: robertwb
Type: defect | Status: needs_work
Priority: major | Milestone: sage-4.8
Component: coercion | Keywords: sd35
Work_issues: | Upstream: N/A
Reviewer: | Author: Simon King
Merged: | Dependencies: #11900 #715
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Comment(by jpflori):
Replying to [comment:82 SimonKing]:
> Hi Jean-Pierre, Replying to [comment:81 jpflori]:
> > I guess you're solution should be the right one because resetting the
coercion cache solves the problem, so dealing with it should be enough for
the example in the ticket description.
> But it is not so easy because...
> > Only one copy gets cached in _action_hash because the curves are equal
(==) but not identical (is).
> ... elliptic curves are not unique parents.
Yep :)
>I think it would be a mistake to use a weak reference to the value of
`TripleDict`. I tried and got many errors - and I think this was because
some important data (homsets, actions, ...) was garbage collected even
though there was still a strong reference to domain and codomain. In that
situation, the value must not be garbage collected.
I see...
> > sage: len(L) # mmm got one left!!! not sure where it comes from yet...
> Don't forget the last copy of E that was defined in the loop!
In the new code I posted I explicitely added "del P; del E;" to the loop
so no copy should be left.
What's even stranger is that this remaining copy appears after the second
loop (with random j invariants so different curves) but not after the
first one (with constant j invariant so only one curve)!
>Since I think that a weak reference to the values of `TripleDict` won't
work: What else could one do? Or perhaps I should try again: It could be
that the errors came from the wrong choice of a callback function.
Mmm, have to think more about all of that...
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11521#comment:83>
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