Bugs item #1183455, was opened at 2005-04-15 01:12
Message generated for change (Comment added) made by simonmar
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Category: libraries (other)
Group: 6.4
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: Possible error using concurrency
Initial Comment:
{-
Error description:
In windows xp sp2 with ghc-6-4, GHCi ends with
"internal error: deadlock: main thread blocked in a
strange way"
In RedHat Linux, it just blocks.
A probably cause, it's that the scheduler hasn't yet
run oneThread
before the second putTMVAr, because no memory
allocation has been
requested.
Try on the calls forkIO and runInUnboundThread.
contact info: [EMAIL PROTECTED]
-}
import Control.Concurrent
import Control.Concurrent.STM
import Control.Concurrent.STM.TMVar
main = do
stopFlag <- atomically (do t <- newEmptyTMVar;
return t)
threadDelay 100001
--t <- forkIO $ oneThread stopFlag -- this line would
work fine...
-- but the following one doesn't work.
runInUnboundThread $ oneThread stopFlag
threadDelay 100002
atomically ( putTMVar stopFlag True )
threadDelay 500003
atomically ( putTMVar stopFlag False )
return ()
oneThread stopFlag = do
go <- atomically ( takeTMVar stopFlag )
if go then do putStrLn "-"
oneThread stopFlag
else return ()
----------------------------------------------------------------------
>Comment By: Simon Marlow (simonmar)
Date: 2005-04-19 13:39
Message:
Logged In: YES
user_id=48280
Fixed the strange error message on Windows.
On Unix, the behaviour is correct: your main thread is
waiting for a condition that never happens.
----------------------------------------------------------------------
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https://sourceforge.net/tracker/?func=detail&atid=108032&aid=1183455&group_id=8032
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