Can anyone help Burak? Simon -----Original Message----- From: burak ekici [mailto:ekcburak@hotmail.com] Sent: 24 January 2012 08:12 To: Simon Peyton-Jones Subject: A Garbage Collection Question Dear Dr. Jones, this time I am disturbing you to ask a question about how garbage collection is being managed in parallel GHC? When I use, (compositional) original strategies to parallel any part of a code, what I expect is that none of the created sparks has to be pruned, instead they should be all converted. Since, it is not possible to adopt WEAK policy in this type of strategies, due to losing the potential parallelism. (ref: Seq no more: Better Strategies for Parallel Haskell) However, in my experiments most of created sparks are getting pruned, although I use compositional strategies. Here you can see mentioned part of code, below. What could be the reason? I would be appreciated, if you shed light on the issue? Sorry for the disturbance! Kind regards, Burak. CODE: instance NFData a => NFData [a] where rnf [] = () rnf (x:xs) = rnf x `pseq` rnf xs karatsuba _ [] _ = [] karatsuba _ _ [] = [] karatsuba currentDepth xs ys | (l < 32 || currentDepth >= limit) = mul xs ys | otherwise = (x `add` (replicate l False ++ (z `add` (replicate l False ++ y)))) `Main.using` strategy where l = (min (length xs) (length ys)) `div` 2 (xs0, xs1) = splitAt l xs (ys0, ys1) = splitAt l ys x = (normalize (karatsuba (currentDepth+1) xs0 ys0)) y = (normalize (karatsuba (currentDepth+1) xs1 ys1)) z = (normalize (karatsuba (currentDepth+1) (add xs0 xs1) (add ys0 ys1))) t = (normalize (karatsuba (currentDepth+1) xs0 ys0)) u = (normalize (karatsuba (currentDepth+1) xs1 ys1)) v = z `sub` t `sub` u strategy res = (rnf x) `par` (rnf y) `par` ((rnf z) `par` (rnf t) `par` (rnf u)) `pseq` (rnf v) `pseq` (rnf res)