On 16 Jul 2010 at 12:33, Jim Bosch wrote: > But I don't know much more than this, and I'm also curious to hear the > story told by someone who has more information...why hasn't > multithreading support been added? Does it just add too much overhead > for those who don't need it?
Atomic exchange instructions are a very precious commodity on modern systems and become ever more precious over time. Wherever possible atomic exchange instructions ought to be avoided for the benefit of the whole system. Besides, one of the big problems with a "naive" threading support implementation such as the one just posted is that there are loads of occasions (e.g. when checking for an overload of a virtual function) when you unlock, do less than 100 cycles of work which doesn't need the unlock and relock. That's crazy, and it hammers performance across your entire system. What was discussed on here many months ago was a simple "hanging lock" system which avoids the problem above. It will however also require source code changes to code using Boost.Python, but wrapper generators like Py++ would take most of the pain. The problem, as always, is funding the time of those to implement a proper solution which would pass muster under peer review. The naïve implementation is not suitable for mainline, and I agree it should be kept out until it's done properly. Annoyingly you could probably get a full and proper implementation for just ~US$7-8k as it's a feature most Boost developers would feel very favourably toward. HTH, Niall -- Technology & Consulting Services - ned Productions Limited. http://www.nedproductions.biz/. VAT reg: IE 9708311Q. Company no: 472909. _______________________________________________ Cplusplus-sig mailing list Cplusplus-sig@python.org http://mail.python.org/mailman/listinfo/cplusplus-sig
