Jason Dagit wrote:
On Wed, Apr 14, 2010 at 3:13 PM, Daniel Fischer
<daniel.is.fisc...@web.de <mailto:daniel.is.fisc...@web.de>> wrote:
Am Mittwoch 14 April 2010 23:49:43 schrieb Jason Dagit:
> > It will be interesting to hear what fixes this!
> >
> >
> > forever' m = do _ <- m
> > forever' m
>
> When I define that version of forever, the space leak goes away.
Not with optimisations.
Thanks for pointing that out. I forgot to say so in my email.
Here are two reduced versions of the original program:
<snip>
I find non-termination with a much simpler program than yours (GHC 6.12.1):
\begin{code}{-# OPTIONS -O1 #-}
import Control.Concurrent
import Control.Monad (forever)
main = do
putStrLn "Main thread starting"
forkIO $ do putStrLn "Started thread"
forever $ return ()
putStrLn "Delaying"
threadDelay (1 * 1000000)
putStrLn "Delayed"
\end{code}
If I compile that with "ghc --make -threaded" and run it, with -O1 or
-O2, it burns CPU and never terminates. With -O0 it terminates. So
looks like some optimisation is causing the problem.
I might guess it's something to do with the RTS and threadDelay that's
causing the problem. "Delayed" is never printed on my system, so it
seems like (even when run with +RTS -N2) the original thread is not ever
being rescheduled; perhaps the timeout queue isn't checked properly when
a thread is burning up the CPU like that, and optimisations are on?
Thanks,
Neil.
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