#715: Parents probably not reclaimed due to too much caching
-------------------------------------------------------------------+--------
Reporter: robertwb |
Owner: somebody
Type: defect |
Status: needs_review
Priority: major |
Milestone: sage-pending
Component: coercion |
Resolution:
Keywords: weak cache coercion Cernay2012 | Work
issues:
Report Upstream: N/A |
Reviewers: Jean-Pierre Flori, Simon King
Authors: Simon King, Jean-Pierre Flori | Merged
in:
Dependencies: #9138, #11900, #11599, to be merged with #11521 |
Stopgaps:
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Old description:
> Here is a small example illustrating the issue.
>
> The memory footprint of the following piece of code grows indefinitely.
>
> {{{
> sage: K = GF(1<<55,'t')
> sage: a = K.random_element()
> sage: while 1:
> ....: E = EllipticCurve(j=a); P = E.random_point(); 2*P; del E, P;
>
> }}}
> E and P get deleted, but when 2*P is computed, the action of integers on
> A, the abelian group of rational points of the ellitpic curve, gets
> cached in the corecion model.
>
> A key-value pair is left in coercion_model._action_maps dict:
>
> (ZZ,A,*) : IntegerMulAction
>
> Moreover there is at least also references to A in the IntegerMulAction
> and one in ZZ._action_hash.
>
> So weak refs should be used in all these places if it does not slow
> things too much.
>
> '''To be merged with #11521'''. Apply:
>
> * [attachment:trac_715_combined.patch]
> * [attachment:trac_715_local_refcache.patch]
>
> and '''then''' the tickets from #11521.
New description:
Here is a small example illustrating the issue.
The memory footprint of the following piece of code grows indefinitely.
{{{
sage: K = GF(1<<55,'t')
sage: a = K.random_element()
sage: while 1:
....: E = EllipticCurve(j=a); P = E.random_point(); 2*P; del E, P;
}}}
E and P get deleted, but when 2*P is computed, the action of integers on
A, the abelian group of rational points of the ellitpic curve, gets cached
in the corecion model.
A key-value pair is left in coercion_model._action_maps dict:
(ZZ,A,*) : IntegerMulAction
Moreover there is at least also references to A in the IntegerMulAction
and one in ZZ._action_hash.
So weak refs should be used in all these places if it does not slow things
too much.
'''To be merged with #11521'''. Apply:
* [attachment:trac_715_combined.patch]
* [attachment:trac_715_local_refcache.patch]
* [attachment:trac_715_specification.patch]
and '''then''' the tickets from #11521.
--
Comment (by SimonKing):
I added sage.structure.coerce_dict to the reference manual. I took a
slight modification of the text you suggested to document the purpose of
that module. Note that the text also refers to #11521, but this should be
fine, as #715 and #11521 are mutually dependent, hence, will be merged
together.
Apply trac_715_combined.patch trac_715_local_refcache.patch
trac_715_specification.patch #11521
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/715#comment:207>
Sage <http://www.sagemath.org>
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