[Haskell-cafe] space leak?

2 Nov 2007


      ...
( these two lines are just to fool the gmane post algorithm which 
  complains for top-posting....)
Hi,
 i'm learning Haskell and trying to use the HPDF 1.2 library I've come
 across some large memory  consumption for which I do not understand
 the origin. I've tried heap profiling but without much  success.
This is my code
...
module Main where
...
import Control.Monad.State
import Graphics.PDF
...
data Opcodes = Rect | Ship  deriving (Show)
...
doPage (Rect:ops) = do
     stroke $! Rectangle 10.0 10.0  10.0 10.0
     doPage ops
...
doPage l = return l
...
doOps [] = return ()
...
doOps (Ship:ops) = {-# SCC "OPSHIP" #-}  do  
    p <- addPage Nothing
    ops' <- drawWithPage p $! do 
              strokeColor red
              applyMatrix $ (translate 72.0 72.0)
              doPage ops  
    doOps ops'
...
doOps (op:_) = error ("unexpected " ++ show op)
...
testpdf =  do
   let ops = concat $ replicate 100 (Ship : (replicate 1000 Rect )) 
       pageRect = PDFRect 0 0 
                          (floor $ 21.0/2.54*72.0) (floor $ 29.7/2.54*72.0)
   runPdf "test1.pdf" (standardDocInfo { author=toPDFString "mgubi", 
                                         compressed = False}) 
           pageRect $ doOps ops
...
testpdf' = do  
   let pageRect = PDFRect 0 0 
                  (floor $ 21.0/2.54*72.0) (floor $ 29.7/2.54*72.0)
   runPdf "full.pdf" (standardDocInfo { author=toPDFString "mgubi", 
                                        compressed = False}) 
            pageRect $ sequence_ $ foldM f [] $ replicate 100 $ 
                (\p -> sequence_ $ replicate 1000 $ 
                          drawWithPage p $ stroke $ 
                               Rectangle 0.0 0.0 10.0 10.0)
            where f ps acts = do
                        p <- addPage Nothing
                        acts p    
                        return $ p:ps
...
main = testpdf
now, if I run testpdf' then memory profile is very low and everything
is as expected while if I run testpdf  then the profile grows up to
80MB and more. This is the stripped down version of the original
program  (which is a DVI interpreter) so there I will have also some
StateT and more complicated opcodes. I would  like to know what is
wrong with the above code. Could someone help me? 

thanks,

Massimiliano Gubinelli