[capi-sig] C/API error handling
cbarton at metavr.com
Sun Jul 29 11:44:16 CEST 2007
Hi Joe, was thinking of messing with the memory allocator yes. maybe
there are other areas also, but the memory allocator would be a good
place to start.
This could be a compile time option for python, maybe a module thats
only built in debug mode, or a seperate option.
...test the apis error stability...
So python could initialize etc without failing, and the test code would
have to set the error probability before it runs a script that tests the
Joe Eagar wrote:
> One thing you could do is hack the python allocator to fail every once
> in a while. However, this is likely to cause problems within python
> itself, along with problems with a python api codebase.
> The allocator is in Objects/obmalloc.c in the python source, iirc.
> Campbell Barton wrote:
>> In the Python C api is that your supposed to check every operation
>> succeeds. - Append, a new list, a new float etc.
>> This makes sense, since somebody could append to a list until the
>> system is out of memory.. or whatever.
>> The thing that bothers me is theres no good way to test the error cases.
>> For example in Blender3D and PyGame (the only 2 C API's I'v looked at)
>> - many checks for failed operations are missing. so its possible
>> somebody could run out of ram and crash the API with python.
>> for Blender3D or PyGame it probably dosnt matter a great deal, but in
>> other cases, you'd want to make sure that doing crazy stuff within an
>> exception (for example) wont crash the application.
>> Not just to look at the code and think it should work but actually run
>> the error case.
>> Is there any way to do this?
>> I was thinking there could be a debug mode where python/C API
>> functions like PyObject_New, PyList_Append etc randomly fail a
>> percentage of the time.
>> Then you could run unit tests in a debugger and any crashes could be
>> This isnt an exact approach but if the unit tests run enough times you
>> could be fairly sure its well tested (assuming the unit tests cover
>> the API).
>> Anyone tried this before or does something like this already exist?
Campbell J Barton (ideasman42)
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