Is that true... what about:

module Main where

import Control.Concurrent.MVar import System.Mem.Weak

myFinalizer :: MVar () -> IO () myFinalizer m = do putMVar m () return ()

createMyFinalizer :: IO (MVar (),Weak ()) createMyFinalizer = do m <- newMVar () w <- mkWeakPtr () (Just (myFinalizer m)) return (m,w)

main :: IO () main = do (m,_) <- createMyFinalizer _ <- takeMVar m return ()

Keean Duncan Coutts wrote:

On Tue, 2004-11-23 at 18:01 +0100, Peter Simons wrote:

...

Simon Marlow writes:

...

...

...

Note that the GC only starts the finaliser thread. The program can still terminate before this thread has run to completion [...]

...

If you want anything else, you can implement it.

How do I implement that particular feature? I don't see how I could write a 'main' function that waits for the finalizer thread having terminated.

For all normal threads you can wait for them by making them write to an MVar when they finish and the main thread waits to read from the MVar before finishing itself.

Of course for the finalizer thread you cannot do this since you did not start it. However the fact that finalizers are run in a dedicated thread is itself an implementation detail that you have no control over anyway.

Obviously from what Simon has said, you cannot solve the finalisers problem just by running the finaliser thread to completion (or it'd be done that way already!)

Duncan

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