#715: Parents probably not reclaimed due to too much caching
-------------------------------------------------------------------+--------
Reporter: robertwb |
Owner: somebody
Type: defect |
Status: positive_review
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 nbruin):
* status: needs_review => positive_review
Comment:
'''safer.patch''': `sage/structure/coerce_dict.pyx`
{{{
# This is to cope with a potential racing condition - if garbage
# collection and weakref callback happens right between the
# "if (isinstance(r1,..." and the "del", then the previously
# existing entry might already be gone.
}}}
No, there is no such racing condition. You are holding references
`k1,k2,k3`. You have just looked up the weakreference `r1,r2,r3` to these
keys
and checked that the weakrefs are still alive (and hence that it's not the
case
that one of the `ki` is just a new element that happens to have the same
id as a
now-deceased previous key element in the dict).
Since you are holding references, they cannot die in between, so I don't
think
the
{{{
del self._refcache[<size_t><void *>k1,<size_t><void *>k2,<size_t><void
*>k3]
}}}
needs to be quarded.
It won't hurt, though, and this code will be optimized anyway, so no
effect on
the review.
Concerning `next_odd_prime`: I'm pretty sure we're keeping a list of
primes
somewhere in sage. We might want to look in there rather than have this
snippet
here. Again, not hurtful to do it this way.
'''trac_715_specification.patch''': One line fuzz in application. Do we
care?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/715#comment:220>
Sage <http://www.sagemath.org>
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