August 2002 - Glasgow-haskell-users

>2gb memory usage ==> segementation fault?
by Hal Daume III 06 Aug '02

06 Aug '02

Hi all, me again :) I keep trying to get my program to run through with all my data, but once it hits around 2 or 2 1/2 gb of memory allocated (according to top), it seg faults and emits a rather sizeable (2.5 gb) core dump. Rather than sending around my 5k line program, here's a simple one which exhibits the same problem: -- UseMemory.hs module Main where import Control.Monad import Control.Monad.ST import Data.Array.ST import System mkArrays :: Int -> Int -> ST s (STArray s Int (STArray s Int Int)) mkArrays src dst = newArray_ (0,src) >>= \arr -> mapM_ (\i -> newArray (0,dst) i >>= writeArray arr i) [0..src] >> return arr sumArrays :: STArray s Int (STArray s Int Int) -> ST s Int sumArrays arr = foldM (\s i -> readArray arr i >>= \arr' -> foldM (\s j -> readArray arr' j >>= return . (s+)) s [0..snd (bounds arr')]) 0 [0..snd (bounds arr)] main = do [ssize,dsize] <- getArgs print $ runST (mkArrays (read ssize) (read dsize) >>= sumArrays) I compile with -O2 -fvia-c, and then run: 9:52am enescu:TryMPI/ ./UseMemory 1 20000 +RTS -K128m 20001 9:53am enescu:TryMPI/ ./UseMemory 1 2000000 +RTS -K128m -A64m 2000001 9:54am enescu:TryMPI/ ./UseMemory 100 2000000 +RTS -K128m -A64m Segmentation fault 1858.28u 51.66s 35:26.02 89.8% (The -A is because if you don't increase the GC size, the program executes ridiculously slowly.) Unfortunately, this behavior is entirely predictable; no matter what arguments you use, once it gets to about 2.2 gb of memory usage it dies. (This is running on a solaris 2.8 machine with 8gb main memory, about 5 or 6gb free.) Could someone explain to me what's going on here? - Hal -- Hal Daume III "Computer science is no more about computers | hdaume(a)isi.edu than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume

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Lazy bind...
by MR K P SCHUPKE 05 Aug '02

05 Aug '02

Is there any way to do a lazy bind operation, something like a <- $ getLine return (Constructor $ a) this works for computations in the IO monad :- a <- unsafeInterleaveIO getLine return (Constructor $ a) but I need to do this for a general monad M. Keean Schupke Department of Electrical & Electronic Engineering, Imperial College London.

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RE: infixed implicit parameters
by Simon Peyton-Jones 02 Aug '02

02 Aug '02

Reasonable suggestion, and not hard to implement. Definitions are more troublesome. Currently implicit parameter bindings must be of the form ?x = e I.e. no pattern-matching, function defintions etc. Changing this would be quite a bit more work. One could imagine a) status quo b) allow infix application, but keep binding syntactically restricted c) allow arbitrary binding forms (pattern matching etc) I think (b) is defensible; I don't think (c) is worth the work. But I would prefer to do (b) in sync with Hugs. Let's see what they think. Simon | -----Original Message----- | From: Hal Daume III [mailto:hdaume@ISI.EDU] | Sent: 23 July 2002 18:38 | To: GHC Users Mailing List | Subject: infixed implicit parameters | | | in the cannonical sort with implicit params, i we write | something like: | | mySort :: (?cmp :: a -> a -> Ordering) => [a] -> [a] | mySort [] = [] | mySort (x:xs) = insert x (mySort xs) | where insert x [] = [x] | insert x (y:ys) | | ?cmp x y == GT = y : insert x ys | | otherwise = x : y : ys | | but we cannot write for the second-to-last line: | | x `?cmp` y | | or | | x ?`cmp` y | | any chance this will be changed (my preference would be for | the first one. | | - hal | | -- | Hal Daume III | | "Computer science is no more about computers | hdaume(a)isi.edu | than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume | | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users(a)haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-| haskell-users |

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