random doctest failure in computational-mathematics-with-sagemath.graphiquue_doctest

[luisfe]

I have a random doctest failure on several machines running debian. It does not happen always, never if I doctest the file directly, only with make ptestlong. It is more likely to happen in a virtual machine so I think it is a type of race condition or memory management issue.

Any idea how to debug this?

File "src/sage/tests/books/computational-mathematics-with-sagemath/graphique_docc
test.py", line 112, in sage.tests.books.computational-mathematics-with-sagemath..
graphique_doctest
Failed example:
   for i in srange(-2, 2, 0.2):  # long time
       g += line(desolve_rk4(DE, y(x), ics=[1, i],\
                         step=0.05, end_points=[0,2]))
       g += line(desolve_rk4(DE, y(x), ics=[-1, i],\
                         step=0.05, end_points=[-2,0]))
Exception raised:
   Traceback (most recent call last):
      File "/home/sage/sage/local/lib/python2.7/site-packages/sage/doctest/forkee
r.py", line 681, in _run
       self.compile_and_execute(example, compiler, test.globs)
     File "/home/sage/sage/local/lib/python2.7/site-packages/sage/doctest/forkee
r.py", line 1105, in compile_and_execute
       exec(compiled, globs)
     File "<doctest sage.tests.books.computational-mathematics-with-sagemath.grr
aphique_doctest[50]>", line 3, in <module>
       step=RealNumber('0.05'), end_points=[Integer(0),Integer(2)]))
     File "/home/sage/sage/local/lib/python2.7/site-packages/sage/calculus/desoo
lvers.py", line 1378, in desolve_rk4
       sol_2=maxima(cmd).sage()
     File "/home/sage/sage/local/lib/python2.7/site-packages/sage/interfaces/inn
terface.py", line 1081, in sage
       return self._sage_(*args, **kwds)
        return self._sage_(*args, **kwds)
     File "/home/sage/sage/local/lib/python2.7/site-packages/sage/interfaces/maa
xima_abstract.py", line 1238, in _sage_
       maxima=self.parent())
     File "/home/sage/sage/local/lib/python2.7/site-packages/sage/calculus/calcc
ulus.py", line 2210, in symbolic_expression_from_maxima_string
        raise TypeError("unable to make sense of Maxima expression '%s' in Sage""
%s)
   TypeError: unable to make sense of Maxima expression '(kill(sage4)$o44)[[1.00
,-2.0],[1.05,-2.149874965475482],[1.1,-2.298999939830521],[1.15,-2.44662492148799
98],[1.2,-2.591999909207452],[1.25,-2.7343749020044],[1.3,-2.872999899091065],[11
.35,-3.007124899832311],[1.4,-3.135999903712506],[1.45,-3.258874910310362],[1.5,,
-3.374999919279643],[1.55,-3.483624930334245],[1.6,-3.58399994323656],[1.65,-3.66
75374957788335],[1.7,-3.756999973823437],[1.75,-3.828124991202094],[1.8,-3.888000
0009806273],[1.85,-3.935875029535953],[1.9,-3.971000050306113],[1.95,-3.992625077
2044261],[2.0,-4.000000094688424]]' in Sage
**********************************************************************
1 item had failures:
  1 of 117 in sage.tests.books.computational-mathematics-with-sagemath.graphiquu
e_doctest
   [116 tests, 1 failure, 20.81 s]

[Dima Pasechnik]

It looks as if in this case Maxima runs out of memory (most probably,
as doctesting is typically run with many threads) or something
similarly bad happens to it.

There are similar hard to debug doctesting bugs mentioned on trac, e.g. a recent
https://trac.sagemath.org/ticket/28106

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[luisfe]

https://trac.sagemath.org/ticket/27250