Bus error in contour on OSX in master

[efiring]

The test of the new contour code is causing a Bus error: 10 for me on OSX 10.9.5, with both python 2.7.9 and 3.4.3 installed via homebrew. Here is the code as a standalone script sufficient to trigger the error:

import numpy as np
import matplotlib.pyplot as plt

def test_corner_mask():
    n = 60
    mask_level = 0.95
    noise_amp = 1.0
    np.random.seed([1])
    x, y = np.meshgrid(np.linspace(0, 2.0, n), np.linspace(0, 2.0, n))
    z = np.cos(7*x)*np.sin(8*y) + noise_amp*np.random.rand(n, n)
    mask = np.where(np.random.rand(n, n) >= mask_level, True, False)
    z = np.ma.array(z, mask=mask)

    for corner_mask in [False]: #[False, True]:
        fig = plt.figure()
        plt.contourf(z, corner_mask=corner_mask)

test_corner_mask()

[tacaswell]

I can't reproduce this on the linux, which backend are you using?

[jenshnielsen]

I can reproduce in on OSX I spent some time today trying to figure out why with no luck. As far as I can see it only happens when the array is masked and with the new c++ contour code. I think that I have narrowed it down to the PyArg_ParseTuple call:

PyArg_ParseTuple(args, "O&O&O&O&il",
                          &x.converter_contiguous, &x,
                          &y.converter_contiguous, &y,
                          &z.converter_contiguous, &z,
                          &mask.converter_contiguous, &mask,
                          &corner_mask,
                          &chunk_size))

In PyQuadContourGenerator_init (_contour_wrapper.cpp) I am guessing that this may relate to
mask being a Boolean array.

I got the following not very helpfull backtrace:

0x0000000103b9fee0 in numpy::array_view<bool const, 2>::~array_view() ()
   from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib-1.5.dev1-py2.7-macosx-10.10-x86_64.egg/matplotlib/_contour.so
(gdb) bt
#0  0x0000000103b9fee0 in numpy::array_view<bool const, 2>::~array_view() ()
   from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib-1.5.dev1-py2.7-macosx-10.10-x86_64.egg/matplotlib/_contour.so
#1  0x0000000103b9fe95 in numpy::array_view<bool const, 2>::~array_view() ()
   from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib-1.5.dev1-py2.7-macosx-10.10-x86_64.egg/matplotlib/_contour.so
#2  0x0000000103b9fbd5 in PyQuadContourGenerator_init(PyQuadContourGenerator*, _object*, _object*) ()
   from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib-1.5.dev1-py2.7-macosx-10.10-x86_64.egg/matplotlib/_contour.so
#3  0x0000000100051b5b in type_call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#4  0x000000010000f0ea in PyObject_Call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#5  0x000000010008bbd2 in PyEval_EvalFrameEx () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#6  0x0000000100088d7a in PyEval_EvalCodeEx () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#7  0x000000010002d1ae in function_call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#8  0x000000010000f0ea in PyObject_Call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#9  0x000000010008b97b in PyEval_EvalFrameEx () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#10 0x0000000100088d7a in PyEval_EvalCodeEx () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#11 0x000000010002d1ae in function_call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#12 0x000000010000f0ea in PyObject_Call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#13 0x0000000100019ed7 in instancemethod_call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#14 0x000000010000f0ea in PyObject_Call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#15 0x000000010008b97b in PyEval_EvalFrameEx () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#16 0x0000000100088d7a in PyEval_EvalCodeEx () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#17 0x000000010002d1ae in function_call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#18 0x000000010000f0ea in PyObject_Call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#19 0x0000000100019ed7 in instancemethod_call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#20 0x000000010000f0ea in PyObject_Call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#21 0x0000000100056254 in slot_tp_init () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#22 0x0000000100051b5b in type_call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#23 0x000000010000f0ea in PyObject_Call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#24 0x000000010008b97b in PyEval_EvalFrameEx () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#25 0x0000000100088d7a in PyEval_EvalCodeEx () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#26 0x000000010002d1ae in function_call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#27 0x000000010000f0ea in PyObject_Call () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#28 0x000000010008b97b in PyEval_EvalFrameEx () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#29 0x0000000100088d7a in PyEval_EvalCodeEx () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#30 0x000000010008f59d in fast_function () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#31 0x000000010008c400 in PyEval_EvalFrameEx () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#32 0x0000000100088d7a in PyEval_EvalCodeEx () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#33 0x00000001000887f3 in PyEval_EvalCode () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#34 0x00000001000a88a2 in run_mod () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#35 0x00000001000a8945 in PyRun_FileExFlags () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#36 0x00000001000a84e2 in PyRun_SimpleFileExFlags () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#37 0x00000001000b9c5b in Py_Main () from /usr/local/Cellar/python/2.7.9/Frameworks/Python.framework/Versions/2.7/Python
#38 0x00007fff92a475c9 in start () from /usr/lib/system/libdyld.dylib
#39 0x0000000000000000 in ?? ()

[jenshnielsen]

I don't think this relates to the backend. It happens to me too when building the docs with the bare Agg backend (How I originally noticed it while trying to fix the Sphinx issues)

Based on the above traceback I did some experiments. Removing the Py_XDECREF(m_arr) call from the destructor of array_view (~array_view) does seem to resolve it. While this is naturally not a solution it does seem to prevent the Bus error. I guess that either the mask array is destroyed to early.

[jenshnielsen]

I think I see the problem and have a fix in #4223 that seems to resolve the problem for me locally. @efiring can you test if that resolves the problem for you?

[WeatherGod]

If it is the XDECREF call I am thinking of, @mdboom changed it to that
recently to get llvm warnings to go away.

On Sun, Mar 15, 2015 at 6:30 PM, Jens Hedegaard Nielsen <
notifications@github.com> wrote:

I think I see the problem and have a fix in #4223
#4223 that seems to
resolve the problem for me locally. @efiring https://github.com/efiring
can you test if that resolves the problem for you?

—
Reply to this email directly or view it on GitHub
#4222 (comment)
.

[jenshnielsen]

Fixed by #4229