#5970: [with patch, needs work] Weak references in Polynomial Ring cache
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Reporter: SimonKing | Owner: malb
Type: defect | Status: new
Priority: blocker | Milestone: sage-4.0
Component: commutative algebra | Keywords: polynomial ring cache weak
reference
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Changes (by mabshoff):
* priority: major => blocker
Comment:
Replying to [comment:3 SimonKing]:
> Replying to [comment:1 mabshoff]:
> > Ooops, but this does seem to expose some problems:
>
> Sorry, I did not do any tests, since I thought that weak references Just
Work (c), and so the change from a dictionary to a WeakValueDictionary
would be almost trivial.
Hehe, I hope you will remember this now :)
> > And something this low level will definitely '''not''' go into 3.4.2
at this stage.
>
> Again sorry. Since I thought it is almost trivial, I concluded it could
easily be in the next distribution.
This stems from long experience that every even trivial fix has a non-zero
chance of breaking things. Weak references are particularly troublesome in
this context. And 3.4.2 was supposed to be out two days ago and now
William and I will fix the last couple issues today and push out
3.4.2.final, so no potentially risky patches. I can valgrind this in some
4.0.alphaX (assuming the segfaults go away).
> If weak references break cython code at a very fundamental level then I
see ''no chance'' for my approach to work, unless Cython changes.
>
> Won't fix, then?
No, as mentioned in sage-support RobertWB pointed out some other ticket as
guideline to what is wrong.
This patch does not fix the problem the reported in the thread at
http://groups.google.com/group/sage-support/t/ef01dae47c835137 reported,
but it seems to fix something else or is part of the fix to get #5949
resolved, so lets keep this open for now. It seems to be a valuable patch.
Cheers,
Michael
Cheers,
Michael
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5970#comment:4>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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