[Haskell-beginners] space leak

[Uchida Yasuo]

That's right! You solved the mystery of the magic number!

--- Felipe Lessa  wrote:
> You can try to verify this by using L.toChunks and noting how
> many chunks are being created.

-- test.hs
module Main where

import System
import System.IO
import qualified Data.ByteString.Lazy.Char8 as L
import qualified Data.ByteString.Char8 as S

main = do args <- getArgs
          let n = read $ args !! 0
          cs <- L.getContents
          let !a = L.take n cs
              !l = L.length a
          hPutStrLn stderr $ "first chunk : "
            ++ show (S.length $ head $ L.toChunks cs)
          mapM_ (print . L.length) $ L.lines cs
          print a


$ ./gen | head -1000 | ./test 17000 +RTS -sstderr > /dev/null
./test 17000 +RTS -sstderr 
first chunk : 16384
gen: <stdout>: commitAndReleaseBuffer: resource vanished (Broken pipe)
   4,085,671,308 bytes allocated in the heap
       7,659,656 bytes copied during GC
       1,091,072 bytes maximum residency (1001 sample(s))
         540,552 bytes maximum slop
               5 MB total memory in use (1 MB lost due to fragmentation)

  Generation 0:  6507 collections,     0 parallel,  0.10s,  0.13s elapsed
  Generation 1:  1001 collections,     0 parallel,  0.09s,  0.10s elapsed

  INIT  time    0.00s  (  0.00s elapsed)
  MUT   time    2.62s  ( 23.11s elapsed)
  GC    time    0.19s  (  0.23s elapsed)
  EXIT  time    0.00s  (  0.00s elapsed)
  Total time    2.81s  ( 23.34s elapsed)

  %GC time       6.8%  (1.0% elapsed)

  Alloc rate    1,558,678,834 bytes per MUT second

  Productivity  93.2% of total user, 11.2% of total elapsed



--
Regards,
Yasuo Uchida