[Haskell-cafe] Cleaning up threads

[Bas van Dijk]

Note that killing the main thread will also kill all other threads. See:

http://haskell.org/ghc/docs/6.12.1/html/libraries/base-4.2.0.0/Control-Concurrent.html#11

You can use my threads library to wait on a child thread and possibly
re-raise an exception that was thrown in or to it:

http://hackage.haskell.org/package/threads

Regards,

Bas

On Mon, Sep 13, 2010 at 5:32 AM, Mitar <mmitar at gmail.com> wrote:
> Hi!
>
> I run multiple threads where I would like that exception from any of
> them (and main) propagate to others but at the same time that they can
> gracefully cleanup after themselves (even if this means not exiting).
> I have this code to try, but cleanup functions (stop) are interrupted.
> How can I improve this code so that this not happen?
>
> module Test where
>
> import Control.Concurrent
> import Control.Exception
> import Control.Monad
>
> thread :: String -> IO ThreadId
> thread name = do
>  mainThread <- myThreadId
>  forkIO $ handle (throwTo mainThread :: SomeException -> IO ()) $ --
> I want that possible exception in start, stop or run is propagated to
> the main thread so that all other threads are cleaned up
>    bracket_ start stop run
>      where start = putStrLn $ name ++ " started"
>            stop  = forever $ putStrLn $ name ++ " stopped" -- I want
> that all threads have as much time as they need to cleanup after
> themselves (closing (IO) resources and similar), even if this means
> not dying
>            run   = forever $ threadDelay $ 10 * 1000 * 1000
>
> run :: IO ()
> run = do
>  threadDelay $ 1000 * 1000
>  fail "exit"
>
> main :: IO ()
> main = do
>  bracket (thread "foo") killThread $
>    \_ -> bracket (thread "bar") killThread $
>      \_ -> bracket (thread "baz") killThread (\_ -> run)
>
>
> Mitar
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