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

Donald Bruce Stewart dons at cse.unsw.edu.au
Mon Nov 7 07:07:00 EST 2005

> Finalizers aren't guaranteed to be run.  In particular, if the main
> thread exits, then we don't run any outstanding finalizers.  This change
> was made recently, but it turned out that even prior to 6.4 we couldn't
> guarantee to run all outstanding finalizers.
> Does this explain it, or is there something else going on?
> BTW, when you addForeignPtrConcFinalizer to a ForeignPtr created with
> mallocForeignPtr, you're *creating* a finalizer, it doesn't have one to
> start with.  It's pretty expensive to do this.

Ah, right, I see. It's:

     mallocForeignPtr = doMalloc undefined
      where doMalloc :: Storable b => b -> IO (ForeignPtr b)
            doMalloc a = do
              IO $ \s ->
                case newPinnedByteArray# size s of { (# s, mbarr# #) ->
                 (# s, ForeignPtr (byteArrayContents# (unsafeCoerce# mbarr#))
                                  (MallocPtrNoFinalizer mbarr#) #)
                where (I# size) = sizeOf a
So the GC will take care of these thingies?
Now, this probably means that the problem is somewhere else in Joelr's code.

-- Don

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