On Sat, Oct 11, 2003 at 10:58:04PM +0200, Wolfgang Thaller wrote:
If you compile the bleeding-edge GHC from the CVS HEAD, you'll get something else; while "most" threads (those created using "forkIO") are still light-weight threads that are scheduled in just one kernel thread, you can also create threads that get their own operating system thread. This is solves all the problems that lightweight threads can have with foreign (i.e. non-Haskell) libraries. You should also note that no Haskell implementation currently supports SMP; even when multiple kernel threads are used, there is a mutual exclusion lock on the Haskell heap, so a multithreaded Haskell program will use only one CPU on an SMP system. I hope my answer was useful...
That's a painful-sounding state of affairs, though not entirely unexpected. It would be interesting to hear of "BKL breakup" efforts for Haskell runtime systems, though anymore I'm totally ignorant of what the devil is going on in userspace except database-only syscalls. -- wli