#715: Parents probably not reclaimed due to too much caching
-------------------------------------------------------------------+--------
Reporter: robertwb |
Owner: somebody
Type: defect |
Status: needs_work
Priority: major |
Milestone: sage-5.4
Component: coercion |
Resolution:
Keywords: weak cache coercion Cernay2012 | Work
issues:
Report Upstream: N/A |
Reviewers: Jean-Pierre Flori, Simon King, Nils Bruin
Authors: Simon King, Jean-Pierre Flori | Merged
in:
Dependencies: #9138, #11900, #11599, to be merged with #11521 |
Stopgaps:
-------------------------------------------------------------------+--------
Changes (by SimonKing):
* status: positive_review => needs_work
Comment:
There are sporadic segfaults found by some (not all) patchbots on #11370
and #12876 that seem to be related with the weak caching bits.
Here, the cdef attribute `sage.categories.action.Action.S` (that's for
keeping the underlying set of the action) is turned into a weak reference
to the underlying set. Today, I found that there might be an interference
with old code in sage/rings/morphism.pyx, namely:
{{{
cdef class RingHomomorphism(RingMap):
def __init__(self, R, S):
"""
Create a lifting ring map.
EXAMPLES::
sage: f = Zmod(8).lift() # indirect doctest
sage: f(3)
3
sage: type(f(3))
<type 'sage.rings.integer.Integer'>
sage: type(f)
<type 'sage.rings.morphism.RingMap_lift'>
"""
from sage.categories.sets_cat import Sets
H = R.Hom(S, Sets())
RingMap.__init__(self, H)
self.S = S # for efficiency
try:
S._coerce_(R(0).lift())
except TypeError:
raise TypeError, "No natural lift map"
cdef _update_slots(self, _slots):
self.S = _slots['S']
Morphism._update_slots(self, _slots)
cdef _extra_slots(self, _slots):
_slots['S'] = self.S
return Morphism._extra_slots(self, _slots)
}}}
Hence, `RingHomomorphism` uses the S attribute as well, but differently.
And aren't there actions that are ring homomorphisms?
I think it is worth trying to rename the `S` attribute of Action. I put it
to "needs work", because I doubt that flaky segfaults are acceptable.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/715#comment:221>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
