On Tue, Apr 29, 2008 at 11:47 PM, Stephen J. Turnbull <stephen(a)xemacs.org&gt; wrote: The word "stackless" appears to be a misnomer. Any idea where that came from? I wrote a package that does this some years ago. Look for my name and "BERT"; it's probably still floating around on the web somewhere. I don't think we really want to go in this direction. Here's why. 1. You have to choose between two painful alternatives. a. A "fair" scheduler that uses a timer to trigger stack switches: this means pseudo-concurrency between operations on different stacks, which means you have to rewrite pretty much all of your code to use mutexes and condition variables. b. A scheduler that only runs inside of well-defined functions, meaning that a given stack can hog the CPU for arbitrary amounts of time. 2. If you choose 1a, then you wind up doing all the work you would have to do for a "real" thread library anyway. 3. There are several mature, well-debugged thread libraries out there. Why ignore them and start the development and debugging process all over again? 4. XEmacs is already built on a Reactor pattern. The "stackless" architecture is just another version of the Reactor. It won't provide any performance gains over what we have now. If we want better performance, we should look at switching to a Proactor pattern. However, not all platforms support asynchronous I/O adequately, so we would really have to have a Reactor/ Proactor hybrid. 5. The world is going multi-core. Intel is talking about having 80-core processors available in 2 years. The "stackless" architecture uses only 1 core. A "real" thread library can take advantage of multiple cores. I am interested in having a discussion on what it would take to switch from our Reactor-based architecture to a multithreaded one. Such a switch would have serious implications for the Lisp engine and the garbage collector, for example. -- Jerry James http://loganjerry.googlepages.com/ _______________________________________________ XEmacs-Beta mailing list XEmacs-Beta(a)xemacs.org http://calypso.tux.org/cgi-bin/mailman/listinfo/xemacs-beta

Michael Sperber <sperber(a)deinprogramm.de&gt; writes: There is one Scheme implementation (I always forget its name, it is some simple thing or animal) which does continuations by calling using the C stack, but never returning, and occasionally garbage-collecting the entire stack. This is what I call programmer chutzpah. -- David Kastrup, Kriemhildstr. 15, 44793 Bochum _______________________________________________ XEmacs-Beta mailing list XEmacs-Beta(a)xemacs.org http://calypso.tux.org/cgi-bin/mailman/listinfo/xemacs-beta

Michael Sperber writes: Now, there's an interesting idea: Dick Cheney on the MTA! Unfortunately, requires hardware only Eric Raymond is familiar with to implement. _______________________________________________ XEmacs-Beta mailing list XEmacs-Beta(a)xemacs.org http://calypso.tux.org/cgi-bin/mailman/listinfo/xemacs-beta