Hello Neil, Tuesday, April 7, 2009, 7:47:17 PM, you wrote:
para = mapM_ forkIO
I might try that tomorrow and see if it makes a difference to the performance. While the majority of computation is in system calls, quite a few of the threads open files etc, and having them all run in parallel would end up with way too many open handles etc.
if you have too much threads, you may replace forkIO with one more QSem-enabled call: semIO = unsafePerformIO$ newQSem 100 myForkIO = bracket_ (waitQSem semIO) (signalQSem semIO) . forkIO this limit may be much higher than for System.Cmd.system or you may go further and replace it with thread pool approach. the main problem behind is raw calls to forkIO since these increases amount of threads capable to call System.Cmd.system without any control from us -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com