Battle of the garbage collectors, or ARGGHHHHHH!!!!

[Cem Karan]

On Apr 24, 2017, at 8:54 PM, Jon Ribbens <jon+usenet at unequivocal.eu> wrote:

> On 2017-04-24, CFK <cfkaran2 at gmail.com> wrote:
>> Long version: I'm trying to write bindings for python via ctypes to control
>> a library written in C that uses the bdwgc garbage collector (
>> http://www.hboehm.info/gc/).  The bindings mostly work, except for when
>> either bdwgc or python's garbage collector decide to get into an argument
>> over what is garbage and what isn't, in which case I get a segfault because
>> one or the other collector has already reaped the memory.
> 
> Make your Python C objects contain a pointer to a
> GC_MALLOC_UNCOLLECTABLE block that contains a pointer to the
> bwdgc object it's an interface to? And GC_FREE it in tp_dealloc?
> Then bwdgc won't free any C memory that Python is referencing.

OK, I realized today that there was a miscommunication somewhere.  My python code is all pure python, and the library is pure C, and it is not designed to be called by python (it's intended to be language neutral, so if someone wants to call it from a different language, they can).  That means that tp_dealloc (which is part of the python C API) is probably not going to work.

I got interrupted (again) so I didn't have a chance to try the next trick and register the ctypes objects as roots from which to scan in bdwgc, but I'm hoping that roots aren't removed.  If that works, I'll post it to the list.

Thanks,
Cem Karan