[Python-Dev] debug and release python

["Martin v. Löwis"]

>> I.e. even with the change, it would *still* depend on objimpl.h
>> (and other) settings what ABI this debug DLL exactly has.
>>
> I think it does. My proposal was perhaps not clear:  For existing
> python versions, always export _PyObject_DebugMalloc et al.

Hmm. That's still not clear. What are "existing Python versions"?
You can't change them anymore; any change can only affect future,
as-of-yet-non-existing Python versions.

Also, what do you mean by "always"? Even in release builds?
Would this really help? You shouldn't be mixing PyObject_DebugMalloc
and PyObject_Malloc in a single process.

> On new python versions, remove the
> _PyObject_DebugMalloc from the ABI.  Make the switch internal to
> obmalloc.c, so that you can turn on the debug library by recompiling
> pythonxx_d.dll only (currently, you have to recompile the .pyd files
> too!)

That sounds fine.

>> But there are tons of ABI changes that may happen in a debug
>> build. If you want to cope with all of them, you really need to
>> recompile the source of all extensions.
> Are there?  Can you give me an example?

If you define Py_TRACE_REFS, every object has two additional pointers,
which aren't there if you don't. So extensions compiled with it are 
incompatible with extensions compiled without it.

If you define COUNT_ALLOCS, every type object will have additional 
slots; again, you can't mix extensions that have a different setting 
here than the interpreter.

Regards,
Martin