[Haskell-cafe] "Out of memory" if compiled with -O2, why?

[Dmitry Kulagin]

Thank you, it is indeed very similar problem.
Nevertheless it seems that the lst function is not the direct reason, because:
1) if I inline lst (by hands), the problem is still there
2) size of the list is actially not so large - just 15 millions elements

I am almost sure that the reason is Map.fromList - result of the
function perhaps somehow memoized and not released by GC.

Dmitry.

On Wed, Dec 1, 2010 at 8:15 PM, Petr Prokhorenkov
<prokhorenkov at gmail.com> wrote:
> Hi, Dmitry
>
> I recently had the same problem:
> http://www.haskell.org/pipermail/haskell-cafe/2010-November/086450.html
>
> Memory is taken by the list returned by your lst function wich is
> being shared across g,h,i,j,k,l,m,n.
> Apparently there is no safe and easy way to overcome this yet :(
>
> --
> Regards,
> Petr
>
>
>
> On Wed, Dec 1, 2010 at 5:23 PM, Dmitry Kulagin <dmitry.kulagin at gmail.com> wrote:
>> Hi,
>>
>> I have problems with memory leaks and can't find out how to avoid them.
>> I tried to reduce sample to demonstrate the following problems:
>> 1) when compiled without -O2 option, it iconsumes 1582MB (!) total memory
>> 2) when compiled with -O2 option it terminates with "out of memory"
>>
>> Actually I don't understand the reasons, particulary why  GC can't
>> collect already processed objects g,...,n (see code below)?
>>
>> I would appreciate very much any help with this situation.
>> Thanks!
>>
>>
>> module Main where
>>
>> import qualified Data.Map as M
>>
>> len = 15*1024*1024
>> lst from = take len $ zip [from..] [0..]
>>
>> g = M.size $ M.fromList $ lst 0
>> h = M.size $ M.fromList $ lst 0
>> i = M.size $ M.fromList $ lst 0
>> j = M.size $ M.fromList $ lst 0
>> k = M.size $ M.fromList $ lst 0
>> l = M.size $ M.fromList $ lst 0
>> m = M.size $ M.fromList $ lst 0
>> n = M.size $ M.fromList $ lst 0
>>
>> main = do
>>    mapM_ print [g,h,i,j,k,l,m,n]
>>
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>