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Max recursion errors for mathtext on Python 3.6 / OSX #7799
Description
See: MacPython/matplotlib-wheels#3
Errors occur testing 1.5.3 and current v2.x branch on Python 3.6, OSX.
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ERROR: matplotlib.tests.test_mathtext.test_mathtext_cm_53.test
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Traceback (most recent call last):
File "/Users/travis/build/MacPython/matplotlib-wheels/venv/lib/python3.6/site-packages/nose/case.py", line 198, in runTest
self.test(*self.arg)
File "/Users/travis/build/MacPython/matplotlib-wheels/venv/lib/python3.6/site-packages/matplotlib/testing/decorators.py", line 53, in failer
result = f(*args, **kwargs)
File "/Users/travis/build/MacPython/matplotlib-wheels/venv/lib/python3.6/site-packages/matplotlib/testing/decorators.py", line 207, in do_test
figure.savefig(actual_fname, **self._savefig_kwarg)
File "/Users/travis/build/MacPython/matplotlib-wheels/venv/lib/python3.6/site-packages/matplotlib/figure.py", line 1563, in savefig
[snip]
File "/Users/travis/build/MacPython/matplotlib-wheels/venv/lib/python3.6/site-packages/pyparsing.py", line 1510, in _parseCache
value = cache.get(lookup)
File "/Users/travis/build/MacPython/matplotlib-wheels/venv/lib/python3.6/site-packages/pyparsing.py", line 1459, in get
return cache.get(key, not_in_cache)
RecursionError: maximum recursion depth exceeded
https://s3.amazonaws.com/archive.travis-ci.org/jobs/187592465/log.txt
Further investigation reveals:
- error does not occur when running the individual mathtext tests, e.g. with
python tests.py matplotlib.tests.test_mathtext, but only when running these tests as part of a full test suitepython tests.py; - when dropping into the debugger on the test failure -
python tests.py --pdb- this sequence of commands also cause the recursion error:
from matplotlib.font_manager import FontProperties
from matplotlib import mathtext as mt
my_p = mt.Parser()
backend = mt.MathtextBackendPath()
font_output = mt.BakomaFonts(FontProperties(), backend)
my_str = '$\\sqrt{1+\\sqrt{1+\\sqrt{1+\\sqrt{1+\\sqrt{1+\\sqrt{1+\\sqrt{1+x}}}}}}}$'
my_p._state_stack = [my_p.State(font_output, 'default', 'rm', 100, 72)]
my_p._em_width_cache = {}
result = my_p._expression.parseString(my_str)
print(result)
The same sequence of commands run on its own in Python 3.6, passes.
This string also generates the recursion errors, when dropped into the debugger:
r'$\cos{1 + \sqrt{1 + \sqrt{1 + \sqrt{1 + \sqrt{1 + \sqrt{1+\cos{1+x}}}}}}}$'
but not:
r'$\cos{1 + \sqrt{1 + \sqrt{1 + \sqrt{1 + \sqrt{1 + \cos{1+\cos{1+x}}}}}}}$'
r'$\cos{1 + \cos{1 + \cos{1 + \cos{1 + \cos{1 + \cos{1+\cos{1+x}}}}}}}$'
r'$\sqrt{1 + \sqrt{1 + \sqrt{1 + \sqrt{1 + \sqrt{1+\sqrt{1+x}}}}}}$'
It looks like there is some horrible global state in the MathText module or pyparsing that is being triggered only under certain circumstances.
@mdboom - can you reproduce? Any insights into the problem?
Activity
matthew-brett commentedon Jan 14, 2017
@mdboom - do you have any time to look into this one? Or any suggestions as to how to investigate further?
tacaswell commentedon Jan 15, 2017
Can the recursion limit on travis be pushed up? The test runner adds a whole bunch of layers, I wonder if we were always sitting on the limit?
matthew-brett commentedon Jan 15, 2017
Had a shot at that - but now tests all failing - https://travis-ci.org/MacPython/matplotlib-wheels/jobs/192055053#L1757 - something to do with the results images change?
jkseppan commentedon Jan 15, 2017
That Travis log looks like it's installing matplotlib from a wheel, and as of recently the wheels don't include test images.
MAINT: add ability to specify recursionlimit
MAINT: add ability to specify recursionlimit
matthew-brett commentedon Jan 16, 2017
OK - I have solved the test images problem - see discussion over at #7757 (comment) .
Upping the recursion limit does make the tests pass on Python 3.6 - see https://travis-ci.org/MacPython/matplotlib-wheels/jobs/192072933
I've submitted a couple of PRs to add the ability to specify the recursion limit to the test function, see #7843, #7849.
Once those are merged, I think wheel building will be OK for master and for the 2.x branch.
tacaswell commentedon Jan 17, 2017
I can now reproduce this on linux as will, but only if I run the test suite not parallel.
tacaswell commentedon Jan 17, 2017
Also, I wonder if that very deep recursion a performance bottle neck that we should be looking into.
matthew-brett commentedon Jan 17, 2017
It's certainly crazy slow to do the parsing - at one point I ran 1000 parses of that multiply nested sqrt string, and it took something like 30 seconds.
dstansby commentedon Feb 21, 2017
I've just run a plain
pyteston python 3.6, OSX, and I'm not getting the above errors. Perhaps this was fixed by all the recent changes to testing?QuLogic commentedon Feb 22, 2017
Plain
pytestdoes not run any of @matthew-brett's changes since those are part ofmatplotlib.testwhich isn't called that way. I don't recall much that would have had an effect here, though. And 3.6 on Travis/Linux never seemed to have the problem...tacaswell commentedon Feb 22, 2017
What does running plain
pytestmiss?QuLogic commentedon Feb 22, 2017
Anything custom in
tests.pyandmatplotlib.test(), so the recursion limit increase and the warning filter thing. But the default recursion limit is to not change anything anyway, and I think we've already fixed everything that triggers the warnings.QuLogic commentedon Nov 23, 2021
We don't support Python 3.6, Matplotlib 2(ish), and the recursion limit stuff was removed, so I think there's nothing to do here.