Is this just a problem of spawning too many forkIO resources that never produce a result? I was thinking of trying something like the following in System.Timeout's place:
module Main where
import Control.Concurrent.MVar import Control.Concurrent import Data.Maybe
timeout :: Int -> IO a -> IO (Maybe a) timeout time action = do someMVar <- newEmptyMVar -- MVar is a Maybe timeoutThread <- forkIO $ nothingIzer time someMVar forkIO $ actionRunner action someMVar timeoutThread takeMVar someMVar >>= return where nothingIzer time mvar = threadDelay time >> putMVar mvar Nothing actionRunner action mvar timeoutThread = do res <- action killThread timeoutThread putMVar mvar $ Just res
main :: IO () main = do res <- timeout (5 * 10 ^ 6) (getLine >>= putStrLn) case res of Nothing -> putStrLn "Timeout" Just x -> putStrLn "Success"
On Tue, Mar 23, 2010 at 11:31 AM, Roel van Dijk
I tried a few things. First I added another timeout to main, so the program kills itself after a few seconds.
doit :: IO (Maybe ()) doit = timeout 12000000 $ {- yield >> -} return ()
main :: IO () main = do _ <- timeout 5000000 $ forever doit return ()
This program failed to terminate. But when I compiled -with threaded and added a yield to doit, it worked (kinda). If the timeout in doit is not too long, like 200 milliseconds, the program has constant space usage. But when I increased the timeout in doit to 12 seconds I got a stack overflow.
I'll investigate further when I have more time.
Regards, Roel