Mailman 3 February 2012 - cython-devel

Bug in Cython producing incorrect C code
by Konrad Hinsen Feb. 12, 2012

Feb. 12, 2012

Compiling the attached Cython file produced the attached C file which has errors in lines 532-534: __pyx_v_self->xx = None; __pyx_v_self->yy = None; __pyx_v_self->zz = None; There is no C symbol "None", so this doesn't compile. I first noticed the bug in Cython 0.15, but it's still in the latest revision from Github. Konrad.

6 24

OpenCL support
by mark florisson Feb. 9, 2012

Feb. 9, 2012

Hey, I created a CEP for opencl support: http://wiki.cython.org/enhancements/opencl What do you think? Mark

6 20

memoryview slices can't be None?
by Dag Sverre Seljebotn Feb. 8, 2012

Feb. 8, 2012

I just realized that cdef int[:] a = None raises an exception; even though I'd argue that 'a' is of the "reference" kind of type where Cython usually allow None (i.e., "cdef MyClass b = None" is allowed even if type(None) is NoneType). Is this a bug or not, and is it possible to do something about it? Dag Sverre

3 16

Re: [Cython] [cython-users] Re: How to find out where an AttributeError is ignored
by mark florisson Feb. 2, 2012

Feb. 2, 2012

On 27 January 2012 16:22, mark florisson <markflorisson88(a)gmail.com> wrote: > On 27 January 2012 15:47, Simon King <simon.king(a)uni-jena.de> wrote: >> Hi all, >> >> I am still *very* frustrated about the fact that Cython does not tell >> where the error occurs. Since about one week, I am adding lots and >> lots of lines into Sage that write a log into some file, so that I get >> at least some idea where the error occurs. But still: Even these >> extensive logs do not provide a hint on what exactly is happening. >> >> How can I patch Cython such that some more information on the location >> of the error is printed? I unpacked Sage's Cython spkg, and did "grep - >> R ignored .", but the code lines containing the word "ignored" did not >> seem to be the lines that are responsible for printing the warning >> message >> Exception AttributeError: 'PolynomialRing_field_with_category' >> object has no attribute '_modulus' in ignored >> >> Can you point me to the file in Sage's Cython spkg which is >> responsible for printing the warning? >> >> Best regards, >> Simon > > These messages are written by PyErr_WriteUnraisable, which is a > CPython C API function that writes unraisable exceptions. There are > typically two reasons for unraisable exceptions: > > 1) as Robert mentioned, a function that does not allow propagation > of exceptions, e.g. > > cdef int func(): > raise Exception > > Here there is no way to propagate the raised exception, so > instead one should write something like > > cdef int func() except -1: ... > > Alternatively one may use 'except *' in case there is no error > indicator and Cython should always check, or "except ? -1" which means > "-1 may or may not indicate an error". > > 2) in deallocators or finalizers (e.g. __dealloc__ or __del__) > > For functions the right thing is to add an except clause, for > finalizers and destructors one could use the traceback module, e.g. > > try: > ... > except: > traceback.print_exc() > > If this all still doesn't help, try setting a (deferred) breakpoint on > __Pyx_WriteUnraisable or PyErr_WriteUnraisable. Actually, I don't see why the default is to write unraisable exceptions. Instead Cython could detect that exceptions may propagate and have callers do the check (i.e. make it implicitly "except *"). Was this not implemented because Cython only knows whether functions may propagate exceptions at code generation time by looking at the presence of an error label? Maybe it could keep code insertion points around for every call to such a potential function and if the function uses the error label have the caller perform the check? Although I do forsee problems for external such functions... maybe Cython could have it's own threadstate regardless of the GIL which would indicate whether an error has occurred? e.g. CyErr_Occurred()?

4 11

Cython's view on a common benchmark suite (was: Re: [Speed] Buildbot Status)
by Stefan Behnel Feb. 2, 2012

Feb. 2, 2012

Brett Cannon, 01.02.2012 18:25: > to prevent this from either ending up in a dead-end because of this, we > need to first decide where the canonical set of Python VM benchmarks are > going to live. I say hg.python.org/benchmarks for two reasons. One is that > Antoine has already done work there to port some of the benchmarks so there > is at least some there that are ready to be run under Python 3 (and the > tooling is in place to create separate Python 2 and Python 3 benchmark > suites). Two, this can be a test of having the various VM contributors work > out of hg.python.org if we are ever going to break the stdlib out for > shared development. At worst we can simply take the changes made at > pypy/benchmarks that apply to just the unladen benchmarks that exists, and > at best merge the two sets (manually) into one benchmark suite so PyPy > doesn't lose anything for Python 2 measurements that they have written and > CPython doesn't lose any of its Python 3 benchmarks that it has created. > > How does that sound? +1 FWIW, Cython currently uses both benchmark suites, that of PyPy (in Py2.7) and that of hg.python.org (in Py2.7 and 3.3), but without codespeed integration and also without a dedicated server for benchmark runs. So the results are unfortunately not accurate enough to spot minor changes even over time. https://sage.math.washington.edu:8091/hudson/view/bench/ We would like to join in on speed.python.org, once it's clear how the benchmarks will be run and how the data uploads work and all that. It already proved a bit tricky to get Cython integrated with the benchmark runner on our side, and I'm planning to rewrite that integration at some point, but it should already be doable to get "something" to work now. I should also note that we don't currently support the whole benchmark suite, so there must be a way to record individual benchmark results even in the face of failures in other benchmarks. Basically, speed.python.org would be useless for us if a failure in a single benchmark left us without any performance data at all, because it will still take us some time to get to 100% compliance and we would like to know if anything on that road has a performance impact. Currently, we apply a short patch that adds a try-except to the benchmark runner's main loop before starting the measurements, because otherwise it would just bail out completely on a single failure. Oh, and we also patch the benchmarks to remove references to __file__ because of CPython issue 13429, although we may be able to work around that at some point, specifically when doing on-the-fly compilation during imports. http://bugs.python.org/issue13429 Also note that benchmarks that only test C implemented stdlib modules (re, pickle, json) are useless for Cython because they would only end up timing the exact same code as for plain CPython. Another test that is useless for us is the "mako" benchmark, because most of what it does is to run generated code. There is currently no way for Cython to hook into that, so we're out of the game here. We also don't care about program startup tests, obviously, because we know that Cython's compiler overhead plus an optimising gcc run will render them meaningless anyway. I like the fact that there's still an old hg_startup timing result lingering around from the time before I disabled that test, telling us that Cython runs it 99.68% slower than CPython. Got to beat that. 8-) Stefan

1 0

Re: [Cython] distutils extension pxd problem
by Dimitri Tcaciuc Feb. 2, 2012

Feb. 2, 2012

> Date: Thu, 02 Feb 2012 08:11:16 +0100 > From: Stefan Behnel <stefan_ml(a)behnel.de> > To: Core developer mailing list of the Cython compiler > <cython-devel(a)python.org> > Subject: Re: [Cython] distutils extension pxd problem > Message-ID: <4F2A3714.7000704(a)behnel.de> > Content-Type: text/plain; charset=UTF-8 > > Dimitri Tcaciuc, 02.02.2012 01:53: >> I bumped into an issue where my .pyx file doesn't see its matching >> .pxd file. Here's a build test to show the problem If I change my >> target package from `b.a` to just `a`, it works as expected. Running >> `cython src/a.pyx` works as expected as well, but not the Extension. >> >> ---- >> >> PYTHON setup.py build_ext --inplace >> PYTHON -c "from b import a" >> >> ######## setup.py ######## >> >> from distutils.core import setup >> from distutils.extension import Extension >> from Cython.Distutils import build_ext >> >> ext_modules = [ >> Extension("b.a", ["src/a.pyx"]) >> ] >> >> setup( >> cmdclass = {'build_ext': build_ext}, >> ext_modules = ext_modules >> ) >> >> ######## b/__init__.py ######## >> >> ######## src/a.pxd ######## >> >> cdef class X: >> cdef object foo >> >> ######## src/a.pyx ######## >> >> cdef class X: >> >> def __cinit__(self): >> self.foo = 1 >> >> x = X() >> >> ---- >> >> Traceback (most recent call last): >> File "<string>", line 1, in <module> >> File "a.pyx", line 7, in init b.a (src/a.c:793) >> File "a.pyx", line 5, in b.a.X.__cinit__ (src/a.c:488) >> AttributeError: 'b.a.X' object has no attribute 'foo' >> >> ---- > > Any reason you cannot rename "src" to "b"? Because that would fix your > problem. Cython basically uses the same algorithm for finding package > content as Python, i.e. it will look inside the package "b" when looking > for "b.a". And "a.pxd" is not in "b" in your setup. > > Stefan > This certainly looks like the cleanest solution now. I have some mixed C++ bits in src/ so I thought to keep compiled/interpreted bits separate, if possible. Dimitri.

1 0

distutils extension pxd problem
by Dimitri Tcaciuc Feb. 2, 2012

Feb. 2, 2012

Hey everyone, I bumped into an issue where my .pyx file doesn't see its matching .pxd file. Here's a build test to show the problem If I change my target package from `b.a` to just `a`, it works as expected. Running `cython src/a.pyx` works as expected as well, but not the Extension. ---- PYTHON setup.py build_ext --inplace PYTHON -c "from b import a" ######## setup.py ######## from distutils.core import setup from distutils.extension import Extension from Cython.Distutils import build_ext ext_modules = [ Extension("b.a", ["src/a.pyx"]) ] setup( cmdclass = {'build_ext': build_ext}, ext_modules = ext_modules ) ######## b/__init__.py ######## ######## src/a.pxd ######## cdef class X: cdef object foo ######## src/a.pyx ######## cdef class X: def __cinit__(self): self.foo = 1 x = X() ---- Traceback (most recent call last): File "<string>", line 1, in <module> File "a.pyx", line 7, in init b.a (src/a.c:793) File "a.pyx", line 5, in b.a.X.__cinit__ (src/a.c:488) AttributeError: 'b.a.X' object has no attribute 'foo' ---- Any idea what's going on here? Thanks, Dimitri.

2 2