[Haskell-cafe] Re: FPS: Finalizers not running (was Memory usageoutside of the Haskell heap)

[Simon Marlow]

On 06 November 2005 18:38, Joel Reymont wrote:

> You need to do something like this to force them to run, apparently
> 
> main = do foo $ Prelude.concat $ replicate 100 data_
> 
> Just triggering the GC with performGC doesn't do it.
> 
> The really odd thing is that if I setup a C finalizer (see below)
> then it's triggered once and the whole thing crashes with a bus
> error. Duncan reported that it segfaulted for him as well.
> 
> installFinalizer fps@(P.PS fp _ _) =
>      addForeignPtrFinalizer finalizer fp
> 
> foreign import ccall unsafe "finalizer" finalizer :: FinalizerPtr
> Word8 
> 
> where the finalizer itself is
> 
> #include <stdio.h>
> 
> void finalizer(char *p) {
>          printf("--- Finalized: %x\n", p);
> }

This crash is due to driver error, I'm afraid.  You should have written:

foreign import ccall unsafe "&finalizer" 
  finalizer :: FinalizerPtr Word8 

(note the "&").

Cheers,
	Simon