On 29 June 2010 13:05, Nick Coghlan <ncoghlan@gmail.com> wrote:
Full agreement. Ironclad, a project to enable the use of Python C extensions with IronPython - which has a generational moving GC, uses a hybrid approach. It allows C extensions to use reference counting but manipulates the reference count so that it can only drop to zero once there are no references left on the IronPython side. There are complications with
On Tue, Jun 29, 2010 at 9:54 AM, Michael Foord <fuzzyman@gmail.com> wrote: this approach, which Ironclad handles, but that would be much easier when we have control over the implementation (Ironclad doesn't change the IronPython implementation).
No link I'm afraid, sending from a mobile device.
Incidentally, Ironclad also 'fakes' the GIL as IronPython has no GIL. In
theory this could cause problems for C extensions that aren't thread safe but that hasn't yet been a problem in production (Ironclad is mainly used with numpy).
How much do you know about Resolver's licensing setup for Ironclad?
http://www.resolversystems.com/products/ironclad/ Ironclad is MIT licensed, but it is *very* tightly coupled to IronPython and .NET (it works primarily through the .NET FFI and uses a fair bit of C#). It may well be useful for inspiration, but I don't know how re-usable it is likely to be.
Combining Ironclad with a Boehm GC enabled PyMalloc mechanism might be
Boehm is a conservative collector, so whilst it may well be a "good first step" it can leak memory like a sieve... Mono has always had this problem and is finally getting rid of its conservative collector. The PyPy guys have experience in this area.
a fruitful avenue of research on the way to a free-threading CPython implementation. Losing deterministic refcounting for pure Python code is no longer as big an issue as it once was, as many of the tricks it used to enable are now better covered by context managers.
Right, and *most* of the alternative implementations are not reference counted - so relying on reference counting semantics has been discouraged by users of these platforms for a while now. All the best, Michael
Cheers, Nick.
-- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia