"Phillip J. Eby" <[EMAIL PROTECTED]> writes: > At 09:30 AM 9/29/2005 -0600, Bruce Eckel wrote: >>This paper looks very interesting and promises some good ideas. It >>also looks like it will require time and effort to digest. >> >>I've only read the first few pages, but one thing that does leap out >>is at the beginning of section 3, they say: >> >>"... a purely-declarative language is a perfect setting for >>transactional memory." >> >>What's not clear to me from this is whether STM will work in a >>non-declarative language like Python. > > I spent a few weekends studying that paper earlier this year in order to > see if anything could be stolen for Python; my general impression was "not > easily" at the least. One notable feature of the presented concept was > that when code would otherwise block, they *rolled it back* to the last > nonblocking execution point. In a sense, they ran the code backwards, > albeit by undoing its effects. They then suspend execution until there's a > change to at least one of the variables read during the forward execution, > to avoid repeated retries. > > It was a really fascinating idea, because it was basically a way to write > nonblocking code without explicit yielding constructs. But, it depends > utterly on having all changes to data being transactional, and on being > able to guarantee it in order to prevent bugs that would be just as bad as > the ones you get from threading.
Oh yes, if implemented this really has be baked thoroughly into the implementation. It's not something that can be implemented as a library (as far as I can see, anyway). > Oddly enough, this paper actually demonstrates a situation where having > static type checking is in fact a solution to a non-trivial problem! It > uses static type checking of monads to ensure that you can't touch > untransacted things inside a transaction. Well, this is an extension of the way Haskell deals with side-effects in general... but yes, it's interesting to be sure. Cheers, mwh -- People think I'm a nice guy, and the fact is that I'm a scheming, conniving bastard who doesn't care for any hurt feelings or lost hours of work if it just results in what I consider to be a better system. -- Linus Torvalds _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
