Hi, for some concurrency abstractions I decided to use deadlock detection by means of exceptions which didn't work out as expected. Below is some simplifed source code showing the problem: My assumption was since GHC should be able to detect that the child still has a reference to mv_should_work -- although in an exception handler -- the RTS would never decide to kill the other thread. Unluckily, this assumption turned out to be false. Did I overestimate GHC's capabilities or is this a bug? Especially as ghc-5.02.2 shows the desired behaviour (you just need to drop the "Control.")... Instead of exiting silently, the program terminates in the exception handler in the main thread with ghc-5.04. \begin{code} module Main where import Concurrent import qualified Control.Exception main = do mv_should_work <- newEmptyMVar mv_deadlock <- newEmptyMVar forkIO $ do Control.Exception.catch (takeMVar mv_deadlock) -- deadlock (\ e -> putMVar mv_should_work ()) yield >> yield >> yield Control.Exception.catch (takeMVar mv_should_work) (\ e -> putStrLn $ "main caught: " ++ (show e)) \end{code} -- Volker Stolz * http://www-i2.informatik.rwth-aachen.de/stolz/ * PGP * S/MIME http://news.bbc.co.uk: `Israeli forces [...], declaring curfews that confine more than 700,000 people to their homes.'