#2762: Excessive heap usage
---------------------------------+------------------------------------------
Reporter: igloo | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 6.10.2
Component: Compiler | Version: 6.11
Severity: normal | Keywords:
Difficulty: Unknown | Testcase:
Architecture: Unknown/Multiple | Os: Unknown/Multiple
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With `Main.hs`:
{{{
module Main (main) where
import InputOutput
main :: IO ()
main = do
let content1 = concat (replicate 1000000 "1x") ++ "0"
let i1 = fst $ input content1
view i1
let content2 = concat (replicate 1000001 "1y") ++ "0"
let i2 = fst $ input content2
view i2
view :: [Char] -> IO ()
view [] = return ()
view (i : is) = i `seq` view is
}}}
and `InputOutput.hs`:
{{{
module InputOutput (input) where
class InputOutput a where
input :: String -> (a, String)
instance InputOutput Char where
input (x : bs) = (x, bs)
instance InputOutput a => InputOutput [a] where
input ('0':bs) = ([], bs)
input ('1':bs) = case input bs of
(x, bs') ->
case input bs' of
~(xs, bs'') -> (x : xs, bs'')
}}}
according to
{{{
ghc -O -prof -auto-all --make Main.hs -fforce-recomp
./Main +RTS -h
}}}
heap usage goes up to about 20M with the HEAD, but only about 200 bytes
with 6.8.2.
This is with 6.11.20081108, but I started investigating with the HEAD when
I saw similar problems with more-or-less 6.10.1.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2762>
GHC <http://www.haskell.org/ghc/>
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