Data growth issue in System.Timeout

[leimy]

(This bug is lhs)

The following seemingly simple code causes infinite data growth and resource exhaustion when the code for System.Timeout does not immediately appear to have a bug with respect to resource utilization.

module Main where

import System.Timeout import Control.Monad

timeoutval :: Int timeoutval = 12 * 10 ^{6 -- 12 seconds}

doit :: IO (Maybe ()) doit = timeout (-1) $ return ()

main :: IO () main = forever $ return ()

[simonmar]

The cause of this was the lazy IORef in Data.Unique, which was fixed recently:

Thu Mar 18 10:44:36 GMT 2010  Simon Marlow <marlowsd@gmail.com>
  * change to use STM, fixing 4 things

Fri Mar 19 12:59:51 GMT 2010  Bas van Dijk <v.dijk.bas@gmail.com>
  * Write the thunk 'next' to the MVar