Petr P <petr.mvd <at> gmail.com> writes: > Is there any reason to use > a `par` b `pseq` (a + b) > instead of > a `par` b `par` (a + b)
(better ask this on parallel-haskell?) > It seems to me that the second variant would work as well: > The main thread would block on one of the sparked computations, I think the main thread would not block at all. Instead, it would start to evaluate a (or b) right away, since (+) is strict, thus duplicating the work of a spark, and causing the spark to fizzle. Why does it work in a `par` b `pseq` a+b ? I am not even sure - there might be a race condition: assume that evaluation (to WHNF) of b (and of a) takes a long time, but b (in the main thread) finishes shortly before a does (in the spark), then the spark still fizzles and its work was in vain? J.W. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
