[Cython] AddTraceback() slows down generators

Vitja Makarov vitja.makarov at gmail.com
Sat Jan 28 20:59:55 CET 2012

2012/1/28 mark florisson <markflorisson88 at gmail.com>:
> On 28 January 2012 19:48, mark florisson <markflorisson88 at gmail.com> wrote:
>> On 28 January 2012 19:41, Vitja Makarov <vitja.makarov at gmail.com> wrote:
>>> 2012/1/28 Stefan Behnel <stefan_ml at behnel.de>:
>>>> Stefan Behnel, 27.01.2012 09:02:
>>>>> any exception *propagation* is
>>>>> still substantially slower than necessary, and that's a general issue.
>>>> Here's a general take on a code object cache for exception propagation.
>>>> https://github.com/scoder/cython/commit/ad18e0208
>>>> When I raise an exception in test code that propagates through a Python
>>>> call hierarchy of four functions before being caught, the cache gives me
>>>> something like a 2x speedup in total. Not bad. When I do the same for cdef
>>>> functions, it's more like 4-5x.
>>>> The main idea is to cache the objects in a reallocable C array and bisect
>>>> into it based on the C code "__LINE__" of the exception, which should be
>>>> unique enough for a given module.
>>>> It's a global cache that doesn't limit the lifetime of code objects  (well,
>>>> up to the lifetime of the module, obviously). I don't know if that's a
>>>> problem because the number of code objects is only bounded by the number of
>>>> exception origination points in the C source code, which is usually quite
>>>> large. However, only a tiny fraction of those will ever raise or propagate
>>>> an exception in practice, so the real number of cached code objects will be
>>>> substantially smaller.
>>>> Maybe thorough test suites with lots of failure testing would notice a
>>>> difference in memory consumption, even though a single code objects isn't
>>>> all that large either...
>>>> What do you think?
>>> We already have --no-c-in-traceback flag that disables C line numbers
>>> in traceback.
>>> What's about enabling it by default?
>>> --
>>> vitja.
>>> _______________________________________________
>>> cython-devel mailing list
>>> cython-devel at python.org
>>> http://mail.python.org/mailman/listinfo/cython-devel
>> I'm quite attached to that feature actually :), it would be pretty
>> annoying to disable that flag every time. And what would disabling
>> that option gain, as the current code still formats the filename and
>> function name.
> Ah, you mean it would cache less code objects for multiple possible
> errors in expressions (or statements) on a single source line?

Not exactly. I mean PyString_Format() is called to add C filename and
C lineno to python function name.


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