Bug in touchForeignPtr?
benjamin.franksen at bessy.de
Tue Nov 30 11:39:14 EST 2004
[re-sending because I got no response yet]
On Tuesday 23 November 2004 13:06, Simon Marlow wrote:
> On 22 November 2004 17:28, Benjamin Franksen wrote:
> > However, what I don't understand is why touchForeignPtr is not
> > honored in my example program: Note that the output text lines from
> > the finalizers appear *before* the last action in the program (which
> > is a second getChar). The finalizers *are* called by the GC, and
> > still the order is wrong.
> Note that the GC only starts the finaliser thread. The program can
> still terminate before this thread has run to completion
I repeat: the program is not yet even near termination when the finalizers get
executed (in teh wrng order).
Here is the example program again (with 3 lines added to the end of main to
illustrate the point):
import Foreign hiding (newForeignPtr)
import System.Mem (performGC)
type A = ForeignPtr Int
type B = ForeignPtr Bool
newA :: IO A
newA = do
(pa::Ptr Int) <- malloc
newForeignPtr pa $ do
putStrLn "before finalizing A"
putStrLn "after finalizing A"
newB :: A -> IO B
newB fpa =
withForeignPtr fpa $ \pa -> do
(pb::Ptr Bool) <- malloc
newForeignPtr pb $ do
putStrLn "before finalizing B"
putStrLn "after finalizing B"
main = do
a <- newA
b <- newB a
putStrLn "Program still not terminated, please hit <enter> again!"
putStrLn "Program termination will now be initiated."
And this is the output:
franksen at linux: .../foreigntouchbug > ./a.out
before finalizing A
after finalizing A
before finalizing B
after finalizing B
Program still not terminated, please hit <enter> again!
Program termination will now be initiated.
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