[Haskell-cafe] Re: Thread pool in GHC
genneth at gmail.com
Thu Aug 4 12:47:56 EDT 2005
Dinh Tien Tuan Anh <tuananhbirm <at> hotmail.com> writes:
> Can thread pool be implemented in GHC ?
> I have a program that is currently using about 12-15 threads (launch and
> kill for infinite times) and when running, especially after Ctrl-C, my
> computer got freezed up. And if i ran it several times, the "Stack
> overflows" occurs.
I made the following a while back. Maybe it's useful...
limitedThreadsWithChannelMapM :: Integer -> (a -> IO b) -> [a] -> IO [MVar b]
limitedThreadsWithChannelMapM lim ioaction x = do
threadpoolcounter <- atomically ( newTVar 0 )
mapM (throttledFork threadpoolcounter . ioaction) x
throttledFork poolcount io = do
atomically ( do
prev <- readTVar poolcount
if prev >= lim then
else writeTVar poolcount (prev+1) )
mvar <- newEmptyMVar
(io >>= putMVar mvar)
(atomically ( readTVar poolcount >>= writeTVar poolcount .
(subtract 1) ) ) )
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