Marcin 'Qrczak' Kowalczyk wrote:
> [...] Now it only sometimes crashes at Ctrl-C. The following progam
> does so too (about 1/10 of runs): [...]
I can't reproduce this. BTW, the foreign object interface will change
in future versions of GHC:
----------------------------------------------------------------
module ForeignObj
( ForeignObj, -- abstract, instance of: Eq
, makeForeignObj -- :: Addr -> IO () -> IO ForeignObj
, foreignObjToAddr -- :: ForeignObj -> Addr
) where ...
----------------------------------------------------------------
I.e. the module name is more consistent, *every* foreign object has
one finalizer, the foreign object is immutable, and foreignObjToAddr
is not in the IO monad any longer. If you use ghc-4.06, you can simply
use the module FFI, which imports Addr/ForeignObj among other things
and offers malloc/free, too:
----------------------------------------------------------------
import FFI
import IO
main:: IO ()
main = do
hSetBuffering stdout NoBuffering
sequence_ . repeat $ do
addr <- malloc 100
makeForeignObj addr (putStrLn "finalizer" >> free addr)
putStrLn "x"
----------------------------------------------------------------
But testing this showed another strange phenomenon: The heap grows
infinitely. :-( A cut-down version, which has the same effect:
----------------------------------------------------------------
import Addr
import Foreign
main:: IO ()
main = do
fo <- mkForeignObj nullAddr
addForeignFinalizer fo (putStrLn "finalizer")
main
----------------------------------------------------------------
An example run:
----------------------------------------------------------------
panne:/tmp > ./Crash1 +RTS -M40M -Sstderr > /dev/null
Crash1 +RTS -M40M -Sstderr
Alloc Collect Live GC GC TOT TOT Page Flts
bytes bytes bytes user elap user elap
263168 262144 120532 0.00 0.03 0.00 0.05 6 134 (Gen: 1)
6355968 385024 8045144 0.08 0.10 0.08 0.16 0 8 (Gen: 0)
803840 8306688 8340236 0.08 0.09 0.17 0.26 0 0 (Gen: 0)
3056640 8605696 11735868 0.10 0.13 0.27 0.39 0 0 (Gen: 1)
2166784 4026368 14311456 0.07 0.07 0.35 0.47 0 0 (Gen: 0)
2547712 2846720 17382480 0.06 0.06 0.42 0.54 0 0 (Gen: 0)
2390016 3350528 20249280 0.07 0.08 0.49 0.63 0 0 (Gen: 0)
2423808 20512768 21617948 0.20 0.26 0.69 0.90 0 0 (Gen: 1)
2452480 3190784 24565464 0.08 0.08 0.77 0.98 0 0 (Gen: 0)
Heap exhausted;
Current maximum heap size is 39997440 bytes;
use `+RTS -M<size>' to increase it.
----------------------------------------------------------------
Things get even stranger: Replacing `putStrLn "finalizer"' with a
simple `return ()' yields constant space:
----------------------------------------------------------------
panne:/tmp > ./Crash2 +RTS -M200k -Sstderr > /dev/null
Crash2 +RTS -M200k -Sstderr
Alloc Collect Live GC GC TOT TOT Page Flts
bytes bytes bytes user elap user elap
263168 262144 120532 0.00 0.03 0.00 0.04 7 132 (Gen: 1)
6355968 385024 120544 0.01 0.01 0.01 0.06 0 5 (Gen: 0)
6356992 385024 120544 0.01 0.01 0.03 0.08 0 0 (Gen: 0)
6356992 385024 120544 0.01 0.01 0.04 0.09 0 0 (Gen: 0)
6356992 385024 120544 0.01 0.01 0.06 0.11 0 0 (Gen: 0)
[... ad infinitum ... ]
----------------------------------------------------------------
Simon: Something wrong with the weak pointer stuff (used for
implementing addForeignFinalizer)?
Puzzled,
Sven
--
Sven Panne Tel.: +49/89/2178-2235
LMU, Institut fuer Informatik FAX : +49/89/2178-2211
LFE Programmier- und Modellierungssprachen Oettingenstr. 67
mailto:[EMAIL PROTECTED] D-80538 Muenchen
http://www.informatik.uni-muenchen.de/~Sven.Panne
