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mdboom opened this issue Nov 16, 2015 · 8 comments
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Something fishy in png reading #5495

mdboom opened this issue Nov 16, 2015 · 8 comments
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@mdboom

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@mdboom
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mdboom commented Nov 16, 2015

We're seeing spurious test failures like:

======================================================================
ERROR: matplotlib.tests.test_cycles.test_marker_cycle.test
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/build/matplotlib/matplotlib/venv/lib/python2.7/site-packages/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/home/travis/build/matplotlib/matplotlib/venv/lib/python2.7/site-packages/matplotlib-1.5.0+34.g43afdd8-py2.7-linux-x86_64.egg/matplotlib/testing/decorators.py", line 53, in failer
    result = f(*args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/venv/lib/python2.7/site-packages/matplotlib-1.5.0+34.g43afdd8-py2.7-linux-x86_64.egg/matplotlib/testing/decorators.py", line 210, in do_test
    self._tol, in_decorator=True)
  File "/home/travis/build/matplotlib/matplotlib/venv/lib/python2.7/site-packages/matplotlib-1.5.0+34.g43afdd8-py2.7-linux-x86_64.egg/matplotlib/testing/compare.py", line 314, in compare_images
    actualImage = _png.read_png_int(actual)
RuntimeError: Error setting jump

and

======================================================================
ERROR: matplotlib.tests.test_cycles.test_marker_cycle.test
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/build/matplotlib/matplotlib/venv/lib/python3.4/site-packages/nose/case.py", line 198, in runTest
    self.test(*self.arg)
  File "/home/travis/build/matplotlib/matplotlib/venv/lib/python3.4/site-packages/matplotlib-1.5.0+34.g43afdd8-py3.4-linux-x86_64.egg/matplotlib/testing/decorators.py", line 53, in failer
    result = f(*args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/venv/lib/python3.4/site-packages/matplotlib-1.5.0+34.g43afdd8-py3.4-linux-x86_64.egg/matplotlib/testing/decorators.py", line 210, in do_test
    self._tol, in_decorator=True)
  File "/home/travis/build/matplotlib/matplotlib/venv/lib/python3.4/site-packages/matplotlib-1.5.0+34.g43afdd8-py3.4-linux-x86_64.egg/matplotlib/testing/compare.py", line 314, in compare_images
    actualImage = _png.read_png_int(actual)
SystemError: error return without exception set

While there were recent changes to PNG writing, there haven't been recent changes to PNG reading, so I'm not sure what's up. But probably shouldn't let this slide...
@mdboom mdboom mentioned this issue Nov 17, 2015
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@tacaswell
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Digging into this a bit, there is one goto exit in _read_png which does not explicitly set an exception before hitting the goto (https://github.com/matplotlib/matplotlib/blob/master/src/_png.cpp#L368) This was last touched in
ba40160 . I have no guess as to why this is showing up intermittently now though. Maybe travis has changed their infrastructure and we are hitting a weird race/edge case on opening files?

@mdboom
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mdboom commented Nov 19, 2015

Digging into this a bit, there is one goto exit in _read_png which does not explicitly set an exception before hitting the goto (https://github.com/matplotlib/matplotlib/blob/master/src/_png.cpp#L368)

I think this is fine actually. The exception is set inside mpl_PyFile_OpenFile (indirectly in PyDict_GetItemString).

I feel this is somehow related to file handling, just not sure what yet.

@mdboom mdboom mentioned this issue Nov 19, 2015
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@smheidrich
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For the record, #5515 didn't fix it: https://travis-ci.org/matplotlib/matplotlib/jobs/94019696

@WeatherGod
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It is important to note that what I haven't seen lately is that we are now
seeing useful exception messages when something goes wrong with reading
images. We are seeing a wider variety of errors now when before it was a
single, generic error message. I suspect the issue might be with whatever
the underlying filesystem is on any particular docker instance.

On Mon, Nov 30, 2015 at 6:08 PM, productivememberofsociety666 <
notifications@github.com> wrote:

For the record, #5515 #5515
didn't fix it: https://travis-ci.org/matplotlib/matplotlib/jobs/94019696

—
Reply to this email directly or view it on GitHub
#5495 (comment)
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@jenshnielsen
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I suspect that most of these issues are related to the nose multiprocessing. If someone sees any of this happen with the 3.5 job, which no longer runs multiprocessing to get correct coverage, please put a reference in here since that would disconfirm my theory

@tacaswell
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I am getting these failures locally as well now.

@mdboom
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mdboom commented Dec 1, 2015

That's promising, I guess. For whatever reason, I've never seen them locally...

@tacaswell
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Also getting these locally

======================================================================
FAIL: matplotlib.tests.test_backend_ps.test_savefig_to_stringio_with_usetex_eps
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/tcaswell/source/other_source/nose/build/lib/nose/case.py", line 198, in runTest
    self.test(*self.arg)
  File "/home/tcaswell/source/my_source/matplotlib/lib/matplotlib/testing/decorators.py", line 138, in wrapped_function
    func(*args, **kwargs)
  File "/home/tcaswell/source/my_source/matplotlib/lib/matplotlib/testing/decorators.py", line 54, in failer
    result = f(*args, **kwargs)
  File "/home/tcaswell/source/my_source/matplotlib/lib/matplotlib/tests/test_backend_ps.py", line 96, in test_savefig_to_stringio_with_usetex_eps
    _test_savefig_to_stringio(format='eps')
  File "/home/tcaswell/source/my_source/matplotlib/lib/matplotlib/tests/test_backend_ps.py", line 54, in _test_savefig_to_stringio
    assert values[0] == values[1]
AssertionError

@mdboom mdboom self-assigned this Dec 10, 2015
@mdboom mdboom closed this as completed in 1c14132 Dec 11, 2015
jenshnielsen added a commit that referenced this issue Dec 11, 2015
@jenshnielsen
Merge pull request #5656 from mdboom/imread-bug
bdb8450 
Fix #5495.  Combine two tests to prevent race cond
jenshnielsen added a commit that referenced this issue Dec 11, 2015
@jenshnielsen
Merge pull request #5656 from mdboom/imread-bug
dfadd4d 
Fix #5495.  Combine two tests to prevent race cond
@QuLogic QuLogic mentioned this issue Nov 3, 2016
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@tacaswell tacaswell mentioned this issue Oct 1, 2017
Closed
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@mdboom @tacaswell @WeatherGod @jenshnielsen @smheidrich