On Wed, 2009-02-11 at 00:05 +0100, Manlio Perillo wrote:
John Ky ha scritto:
Hi Haskell Cafe,
I wrote very short program to sleep for 5 seconds compiled with the -threaded option in ghc on the Mac OS X 1.5.
I am finding that using the sleep function doesn't sleep at all, whereas using threadDelay does:
[...] main = do putStrLn "Waiting for 5 seconds." sleep 5 -- doesn't sleep at all putStrLn "Done."
Anybody know what's happening?
Here is a syscal trace, on Linux: http://hpaste.org/fastcgi/hpaste.fcgi/view?id=1332#a1332
The interesting part: write(1, "Waiting for 5 seconds.\n"..., 23) = 23 rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0 rt_sigaction(SIGCHLD, NULL, {SIG_DFL}, 8) = 0 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0 nanosleep({5, 0}, 0xbf85f5cc) = ? ERESTART_RESTARTBLOCK (To be restarted) --- SIGVTALRM (Virtual timer expired) @ 0 (0) --- sigreturn() = ? (mask now []) write(1, "5\n"..., 2) = 2
So, it seems nanosleep get interruped by a signal.
This works:
import System.Posix
main = do putStrLn "Waiting for 5 seconds." blockSignals $ addSignal sigVTALRM emptySignalSet sleep 5 putStrLn "Done."
So (see my earlier email) `sleep` is lying about what interrupts it :) - George