#6818: [with patch; needs review] maxima interface gets dramatically slower over
time
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Reporter: was | Owner: was
Type: defect | Status: new
Priority: critical | Milestone: sage-4.1.2
Component: interfaces | Keywords:
Reviewer: | Author:
Merged: |
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If you do a few hundred calls to the maxima interface, it gets way way
slower.
{{{
sage: timeit("str(maxima.eval('1+2'))")
5 loops, best of 3: 758 µs per loop
sage: timeit("str(maxima.eval('1+2'))")
625 loops, best of 3: 1.22 ms per loop
sage: timeit("str(maxima.eval('1+2'))")
125 loops, best of 3: 2.98 ms per loop
sage: timeit("str(maxima.eval('1+2'))")
125 loops, best of 3: 3.97 ms per loop
}}}
It turns out that this is caused by computation of the maxima input prompt
number, which uses the following "clever" algorithm to compute "n+1":
{{{
(defmfun makelabel (x)
(when (and $dskuse (not $nolabels) (> (incf dcount) $filesize))
(setq dcount 0)
(dsksave))
(setq linelable ($concat '|| x $linenum))
(unless $nolabels
(when (or (null (cdr $labels))
(when (member linelable (cddr $labels) :test #'equal)
(setf $labels (delete linelable $labels :count 1 :test
#'eq)) t)
(not (eq linelable (cadr $labels))))
(setq $labels (cons (car $labels) (cons linelable (cdr $labels))))))
linelable)
}}}
More precisely, this code "checks
that the list containing all labels does not contain the new label
which it generates. After you create 2*35150 labels, this takes longer
than when maxima starts.", according to Andrej Vodopivec who tracked this
down and told us a simple fix. Put:
{{{
nolabels:true;
}}}
at the beginning of our Maxima session. This is fine for Sage, since Sage
doesn't use the labels in any way.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6818>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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