#15367: Empty lists while creating parents
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Reporter: roed | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-5.13
Component: memleak | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by nbruin):
Replying to [comment:10 SimonKing]:
> Do I understand correctly: Your suggestion is to start with a list (an
actual initialised list) of buckets, but initially each bucket will be
`None` rather than `[]`.
Uh, no. I was more thinking of starting out with a bucket ''list'' of
None. Your interpretation is also possible, but addresses a slightly
different issue. It could be worth doing both, one of the two, or neither.
For your proposal: I don't know what the cost difference is between making
an empty list and putting another reference to None in, i.e., the cost of
{{{
cdef PyList buckets = PyList_New(nbuckets)
for i in range(nbuckets):
PyList_SetItem(buckets,i,None) #I think this works OK for
refcounting
}}}
versus
{{{
cdef PyList buckets = PyList_New(nbuckets)
for i in range(nbuckets):
PyList_SetItem(buckets,i,PyList_New(0))
}}}
If the difference is significant (and it may well be, because increffing
doesn't involve memory allocation) then your interpretation may well have
great benefits (and surely reduced memory footprint).
If you're feeling gutsy, you could just leave the entries in `buckets`
initialized with `NULL` and save on all the incref/decref activity on
None.
Come to think of it, I expect that your interpretation would have the
biggest impact.
--
Ticket URL: <http://trac.sagemath.org/ticket/15367#comment:11>
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