Hello Neil,
Tuesday, April 7, 2009, 2:25:12 PM, you wrote:
> The problem I'm trying to solve is running system commands in
> parallel.
"system commands" means execution of external commands or just system
calls inside Haskell?
> Running a benchmark of issuing 1 million trivial tasks (create,
> modify, read and IO ref) the version without any parallelism is really
> fast (< 0.1 sec), and the version with parallelism is slow (> 10 sec).
> This could be entirely due to space leaks etc when queueing many
> tasks.
i think it's just because use of MVar/Chan is much slower than IORef
activity. once i checked that on 1GHz cpu and got 2 million withMVar-s
per second
i don't understood exactly what you need, but my first shot is
to create N threads executing commands from channel:
para xs = do
done <- newEmptyMVar
chan <- newChan
writeList2Chan chan (map Just xs ++ [Nothing])
replicateM_ numCapabilities $ do
forkIO $ do
forever $ do
x <- readChan chan
case x of
Just cmd -> cmd
Nothing -> putMVar done ()
takeMVar done
--
Best regards,
Bulat mailto:[email protected]
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